Spiderbox Project Thread

[SYCARMS]

It appears your using a new plug. Use an old but good plug that is already colored. If you don't have a good old colored plug then drive the buggy until the porcelain is colored then redo the test. It will be much easier to read. You will be looking at the base of threads, porcelain and ground strap. Color should be a brown. Check and make sure you do not have a vacume leak at the intake. What carb are you running?

[Pripyat]

That may be the oldest plug I've got. There is no vacuum leak. 30mm pumper cvk.

Will an EGR head work with a non-egr valve cover? I'm having a hard time sourcing a big valve head without EGR.

[SYCARMS]

Generally the EGR heads have smaller valves and smaller runners. Non EGR heads are out there I have them in stock with larger valves and runners. Put your stock carb on with around a 125-130 main jet. That 30mm carb is too big.

[Pripyat]

I won't be messing with the buggy much this week but I do have some questions -

I emailed SYC about purchasing a cylinder head through him. After some discussion I realized that if I order one from a shop that does engine work I would want to go ahead and get a port/polish from someone who knows what they are doing. But, I want to play with the big valve head in its stock form and see what the gains are just from the larger ports/valves before the port/polish. So currently I'm trying to source a well made head with large valves to play with. If I find that I'm still wanting more I'll seek a port/polish for the new big valve head.

But, I cannot find a name brand big valve head (58 through 61mm) without EGR just by searching on the internet. Why can I not find a Taida or NCY non-EGR cylinder head with 28/23 valves? I have spent hours searching.

I didn't follow up with SYC to find out what brand he stocks but the only 28/23 non-EGR head I can find is one on ebay under the brand "Charmo". Interestingly it says "Taida" as being the brand. Maybe it is a clone of the Taida head? Interestingly the seller on ebay is the same one I got the terribly cast, crappy head from. I will cry if I order the Charmo head and it has the huge castings extending up into the ports around the valve stems like the other cheap head.

[Shadowfocus603]

http://www.scrappydogscooters.com/12...rformance.html
It's been almost 10 years since I ordered the head at the top of that page so I don't remember much about the casting but I can say it made damn good power. The owner Rick is a great guy that I met through the grapevine when I lived in Vegas.

[Pripyat]

I saw that head but I was worried it had a large combustion volume (for 63mm) and i'd end up better off with slightly smaller valves with a combustion chamber designed for 58 or 61mm.

[ckau]

Have you looked at the pilot jet? I had to change up on the pilot in order to get a acceptable plug reading. I lost my database awhile back so everything I state comes from memory and that is not totally reliable but I think I ended with a 145 main and a 38 pilot. The 30mm carbs I purchased did not have any main or pilot jet sizes stamped on them At first try I could immediately tell they were way too lean. Using a wire gauge, the supplied main was about a 135 and the pilot was some thing like a 28 so I purchased a wide range of main and pilots sizes and started with a sophisticated wild ass guess.

keihin jets part # main- 99101-393, 140 to 160 ranges
pilot- N424-21 35 to 50
This is on a motor 155cc, 30mm port matched head, and a 7/8ID x 28" long exhaust. Your motor configuration will make a difference in jetting.
Your moving along faster than I can respond to the posts but hopefully this info may help.

[ckau]

Originally Posted by Pripyat

I saw that head but I was worried it had a large combustion volume (for 63mm) and i'd end up better off with slightly smaller valves with a combustion chamber designed for 58 or 61mm.

I found the larger cc heads work fine as long as you supply enough air in and out. A large uni, a 1-3/4" id x 6.5" long velocity tube, 30mm carb and 7/8" id exhaust works great. I always focused on packing as much air and fuel as physically possible into the head and enough pipe to move the a/f out. I think it like a air pump, the intake, chamber and exhaust matched to move large volumes of air efficiently. There's tons of variables here but that's a basic concept.

[Pripyat]

I just realized that the head on scrappydog is EGR. What does using an EGR head entail? New valve cover?

[Pripyat]

Work has had me busy and the engine project is in limbo anyway.

I ordered a David Vizard book on head porting. Really interesting stuff. I ordered a Taida big valve head. I plan to post some comparison pictures at some point. Anyone interested in discussing high-level GY6 head theory? Specifically, Vizard talks a lot about valve shrouding. I haven't pulled a caliper out and done any measurements but the head design looks like shrouding isn't really an issue.

There are a couple things I've read that are really interesting. This is still blowing my mind -
-On an engine with a properly tuned exhaust and intake, at TDC of the exhaust stroke, the intake experiences vacuum from the inertia of the exhaust exiting the exhaust port. This happens during the overlap period of the cams. The vacuum experienced at the intake can exceed the vacuum caused by the piston itself in its downward stroke. In order for this to happen the intake/exhaust have to be tuned, and there has to be good flow characteristics on the intake/exhaust valves at low lift.

Interestingly the book covers home flow testing with a vacuum. Basically everything I did was exactly what his book says to do except I didn't spend any time testing at low lift.

Currently I'm trying to find information on the Taida cams but I can't find anything. It is frustrating how little information is out there. I'm tempted to make a cam profiler.

[neo71665]

Originally Posted by Pripyat

I just realized that the head on scrappydog is EGR. What does using an EGR head entail? New valve cover?

Run a non egr valve cover and block off the egr on the head

https://www.amazon.com/NCY-EGR-Block.../dp/B01M1NL97F

Frankly if you have the tools and know how to port a head I would just make one.


For cams with my limited research the biggest issue with cams for these things is the overlap. They pretty much all use the factory specs or don't stray far from it with only the difference in lift. I think if somebody had the time, tools, materials, and money to custom grind some cams to test IMHO I'm almost positive there are gains to be made. I'm almost sure if somebody even took say the specs of an a11 or a12 and dialed in the lobe separation it would wake it up even more. Of course custom grinds get into big money.

[Pripyat]

I was thinking about purchasing a cam with a long lift duration on both intake and exhaust. Then cutting it in half, rotating the intake/exhaust a couple degrees to add overlap, then welding back together. But that seems silly.

Interestingly the Taida EGR head doesn't have functional EGR.

[x-bird]

Originally Posted by Pripyat

Work has had me busy and the engine project is in limbo anyway.

I ordered a David Vizard book on head porting. Really interesting stuff. I ordered a Taida big valve head. I plan to post some comparison pictures at some point. Anyone interested in discussing high-level GY6 head theory? Specifically, Vizard talks a lot about valve shrouding. I haven't pulled a caliper out and done any measurements but the head design looks like shrouding isn't really an issue.

There are a couple things I've read that are really interesting. This is still blowing my mind -
-On an engine with a properly tuned exhaust and intake, at TDC of the exhaust stroke, the intake experiences vacuum from the inertia of the exhaust exiting the exhaust port. This happens during the overlap period of the cams. The vacuum experienced at the intake can exceed the vacuum caused by the piston itself in its downward stroke. In order for this to happen the intake/exhaust have to be tuned, and there has to be good flow characteristics on the intake/exhaust valves at low lift.

Interestingly the book covers home flow testing with a vacuum. Basically everything I did was exactly what his book says to do except I didn't spend any time testing at low lift.

Currently I'm trying to find information on the Taida cams but I can't find anything. It is frustrating how little information is out there. I'm tempted to make a cam profiler.

that's why flow testing a head with the intake manifold and initial exhaust stub in place is so much better. get the I/E ratio dialed in, and you've got your hands on something.

[Pripyat]

I started putting together a cam profiler. It should be accurate to .01mm. As far as cam rotation angle it will be good to around 1/2 degree. Should work OK for comparison purposes. I'm done with coding and circuitry but am waiting on the encoder to come in the mail. I'll post pics at some point. I've got two stock cams and an A12 currently.

Anyone got any unwanted cams lying around I can profile? An already-profiled cam would be awesome so someone can check my work. I'll pay freight. PM me if interested.

[SYCARMS]

There was a point I tried to spec an A8-A14 cams but found that you can spec an 5 A-12 cam and they all spec differently. When a cam is ground the the specs are dialed into the cam grinder as the cam is ground spec plated are also made. The spec plates insure that each cam is ground to the same specs. The problem is they than press the sprockets on they can be off as much as .003" which changes the cam profile. This is why they do not spec the same. You would need the specs off the plates so that you could properly dial in the cam. But the Chinese for some reason will not supply the specs . For instance when I had my cam ground I was given a spec sheet so that when I pressed on the sprocket I could check for accuracy using the degree wheel and dial indicator. Being just .002" on these small engine cams can drastically change the cams profile.

[Pripyat]

My #1 motivation for putting the profiler together is the lack of documentation. There is a grainy JPG of gy6 cam profiles you can find through google images but it is nearly unreadable. I can't find anything on the Taida t1, t100, t300. If I prove my cam profiler I expected to buy one of the taida cams to see what they are and see if they are worth the extra $. I'm hoping they are great but if they aren't i guess we'll all find out at the same time..

[Shadowfocus603]

I just sent an email to my friend Rick at scrappydogscooters who sells all three of those cams to see if I can get lift, duration, etc info on the three cams. Will let you know if I get a response.

[neo71665]

I'm not sure there is a standard sizing on cams. Company one might have an A11 with the same specs as a different company's A10.

It might be out of date but here is a thread on Scootdawg they started listing cam specs.
http://scootdawg.proboards.com/threa...ms-a10-a11-a12

It's a start if nothing and I've seen bigger threads with more info if I can remember where.

[SYCARMS]

Those #'s mean nothing. What is needed is @ .050 " what degree the intake and exhaust open and close,lobe separation, what degree intake lobe is set to, total duration of intake and exhaust, lobe lift and gross valve lift.

[Pripyat]

Yeah it's frustrating. Of all the manufacturers of these cams I'm yet to find an actual spec for one. Surely there is a manufacturer out there that makes repeatable cams. Even the descriptions for the taida cams vary between vendors. Once I prove out the cam profiler I've got to determine which of the three Taida cams would make sense for my engine/needs with very little to go off of.

I'm planning to profile both intake and exhaust simultaneously. It will be easier to set up if I measure at a 90 degree angle from the head surface. Later when I've got the lift/rotation data in excel i would then have to adjust for the angle offset of the lifters. Anyone know the angle the lifters contact the cam? Or how many degrees they are offset?

[Pripyat]

So I have been consumed with my day job. That fact likely won't change until the second half of the year. But, I wasn't joking about the cam profiler. Setup reads both intake and exhaust simultaneously. Rotation angle accuracy to .15 degrees. Lift accuracy to around .01mm. I planned to profile every cam I could get my hands on and post up all the raw data for rotation angle and lift. I'm a little discouraged no one volunteered to contribute to the project by sending unwanted/unused cams so I'm considering holding the data hostage. If you guys want the graphs with rotation angle and lift (as well as the raw data) someone has got to contribute by sending me more cams for profiling. Keep in mind I offered to pay postage in an effort to contribute to the cause.



That is the first attempt at gathering useful data. Next time I'll have the lift probe tolerance tighter (there are minor fluctuations due to the plunger riding on the cam having lateral play) and I'll turn the cam slower so I'll get more data points. I can supposedly increase the data rate on the lift probe which would be really useful. I'll post pictures of my over-complicated cam profiler at some point.

[neo71665]

I'd offer a cam but the only one I have is being used.

[Pripyat]

No problem. I understand if you don't have one to give up for science. Surely someone has something?

I sent that graph to a gearhead buddy of mine. He replied, "No wonder you are having issues. Your cam is machined upside down!"

Here is the setup - Two chinese digital calipers ($10x2), an Arduino Uno clone ($12), an encoder ($18), and some random hardware/electronics misc I had lying around. So about $50.



I had all intentions of hot gluing the encoder to the cam but hot glue does not stick to steel. Tape looks very sloppy but appears to work fine. Rubber bands are applying the downward pressure on the calipers.

[Fink]

What size front hubs did you go with for your Spiderbox. 4 x 4?

[Pripyat]

They are 4/110. I spent a lot of time trying to piece together a cheap solution but wound up going with the pre built hubs from buggydepot.

http://www.buggydepot.com/product/54...gx150-1pc.html

The front rim/tire combo is a pull-off from a chinese ATV.

[Fink]

Originally Posted by Pripyat

They are 4/110. I spent a lot of time trying to piece together a cheap solution but wound up going with the pre built hubs from buggydepot.

http://www.buggydepot.com/product/54...gx150-1pc.html

The front rim/tire combo is a pull-off from a chinese ATV.

whats the difference between those and these?http://www.buggydepot.com/product/33...4-pattern.html
what is the 110mm representing? sorry if its an obvious question

[neo71665]

Originally Posted by Fink

whats the difference between those and these?http://www.buggydepot.com/product/33...4-pattern.html
what is the 110mm representing? sorry if its an obvious question

4/110 is 4 lugs 110mm center to center measurement

4/4 is 4 lugs 4 inches center to center measurement

4/4 is pretty common on golf carts. 4/110 is common on the front of most buggies and used on atvs (pretty universally on all honda 4 wheelers).


It's not obvious if you don't know

[OLDKID]

4 on 4 , or 4 x 4 represents lug pattern . Four lug bolts , 4" apart diagonally center to center . Limits you to few rim choices ---- some small trailer rims ( too skinny ) , golf cart rims ( too wide ) . 4 x 110 represents four lug bolts 110 mm apart ---- many rim choices as it's a common size buggy AND ATV/FOUR WHEELER rim .

[Fink]

So the 4x4 pattern should be fine for a go kart that I don't plan on doing anything crazy with right? worst case i can swap them out later. Quad wheels would look cool but being choked to death by my wife for going way over budget on this thing already wouldn't be optimal. I'm going to run 19x7x8's in the front and 22x11x10's in the rear

[neo71665]

4x4 works fine just pretty much limits you on rim and tire choices to golf cart stuff.

Running atv rims and tire sizes gives you much more tire sizes. Unless you live next to a golf course it's easier to find atv rims also. You can normally find people giving factory atv rims away if they put aftermarket rims on. Hondas use the 4/110 pattern and they are a dime a dozen.

[Pripyat]

This thread is far from over. I've been consumed with work and finishing up my son's Kandi 110cc. I finally gifted the Kandi and I'm shifting my limited free time back over to the sbox.



I'm not taking the cam profiling as seriously as I once was. My measurements are close but since I apparently won't be creating a vast database of public cam data due to lack of cams to profile I'm not as concerned with little nuances in my data/graphs. I typically would gather data three times, compare, then adjust until all three passes are identical. So far I've only done a couple runs with stock and a12, which all required adjusting. I wouldn't publish any of this data as 100% accurate. Only 95%. Here is a12 vs stock -

[Pripyat]

I had read that the stock valves were smaller than 28/23. I measured the stock valves and they are almost identical to the 28/23 Taida head. Where did the smaller stock valve measurement come from or did I just read incorrect info? I'm wondering if the valve seats are different.

Anyway, I took come comparison pictures before I installed the Taida head. Interestingly there were more casting marks than I expected.


Intake:


Exhaust:



Intake:





Exhaust:


Chamber:

[Pripyat]

I ran the buggy a little today. Why is this engine so loud? It is ridiculous. I can't talk to the person sitting in the passenger seat without yelling at anything over 10mph. It isn't the exhaust. I'm guessing it's the cvt?

[Pripyat]

I cleaned up the ports before I put the Taida head on the 61mm engine. I also changed the carb mounting - I removed the black plastic spacer plate. This helped the accelerator pump clear the engine mount. My only concern is the temp of the carburetor. I think that plastic spacer was acting as an insulator. I put my palm on the carb earlier and it felt much warmer than I remember it feeling in the past. I'm still on the stock exhaust.

Anyway, the buggy seems to make plenty of power down low and is very responsive to throttle changes. I seem to have gotten my top speed back, too. I'm right at 35mph on the same straight I've been testing on.



I'm really excited about redoing my exhaust. I'm half-way through the header creation process and have a cheap can en route. I measured the recesses that were cut in the Taida head and ordered carbon steel tubing that fits exactly in the inner groove. Basically the ID of the tube matches the port width and the OD of the tube matches the OD of the first step that is cut into the head. Should seal up nicely and have no step changes in passage diameter all the way out to the silencer.

Honestly I'm not sure if it would be beneficial to step down and increase the exhaust gas velocity (this would increase the vacuum experienced at the valves at TDC) or if it would be better to not step change at all as I plan to do. Anyway, I picked one and went with it. Hopefully next weekend I'll have the header/pipe complete and mounted. OD of my pipe is 1.125" with around 1" ID.

This pipe will fit inside the other pipe I was using. Apparently the last DIY header was 1.125" ID.

[ckau]

[QUOTE=Pripyat;54611]I had read that the stock valves were smaller than 28/23. I measured the stock valves and they are almost identical to the 28/23 Taida head. Where did the smaller stock valve measurement come from or did I just read incorrect info? I'm wondering if the valve seats are different.

If your measuring a head off a Howett motor, The stock Howett heads come with the larger valves. Before aftermarket "performance" heads were available, Howett heads were a highly desirable item. At the time, most all of the gy6 manufacturers used a smaller valve head.

[x-bird]

You're pretty much on themoney with your comment about velocity. If you can make a fixture for your flow bench to attach to a common tube that you can attach to an exhaust stub matching each of the setups you try, you can map it out and get your IE ratio. same goes with making a fixture for the carb opening. run your setup with carb and exhaust and you'll have some good insights as to what works best together.

[Pripyat]

Ckau - thanks for that info.

That makes sense. I would almost be willing to bet that my stock howhit head flowed better than the 28/23 taida head (without porting). The passages are larger on the taida head but the area around the valve boss is a lot better on the stock howhit. I base this off the valve porting book I just read and do not know this as fact.

I suspect the taida head has extra material for a porter to shape as they desire?

I learned earlier that part of the engine noise I noticed was coming from the carburetor vibrating and contacting the engine mount at certain rpms. I'm working on a fix. I'm really eager to get it all back together for this warmer weather. My son slung mud on me from his kandi earlier today. It was great.

[Pripyat]

I got the buggy stuck pretty bad yesterday evening in the swamp behind the house. Was pressure washing it earlier and noticed some things..



Both sides have cracks in the paint along that weld seam. Interestingly the trash buggy I've got has been re-welded around those same seams. I scratched the paint off and sure enough there is a hairline crack that is really difficult to see in images.



Sigh.. What is the best plan of action? I'm thinking grinding down the weld, re-welding, then reinforcing.

[SYCARMS]

Grind it down and re weld. Two causes for this is a bad factory weld or brittle metal.

[neo71665]

Originally Posted by SYCARMS

Grind it down and re weld. Two causes for this is a bad factory weld or brittle metal.

And get used to doing it. Eventually you'll have the entire thing rewelded

[ckau]

The yerf chassis is notorious for weld failure in those spots. the spiderbox put a lot of stress on that area. 3 things to do that will fix the problem. In the pic, triangular gussets are added, double through bolt for the spiderbox and tubes at the corners between the upper and lower frame rails.

[tim]

Hey I like the larger size of those two front gusset. I had some smaller gusset leftover from dirt track days I welded them everywhere I could see a potential problem.I know you're buggy is already painted but here are some different types if you don't want to make your own.

Tim


http://www.jegs.com/pt/Roll+Cage+Gusset

[Pripyat]

It is unbelievable how much time I've spent on this buggy yet I'm not even close to having a "reliable" vehicle. I still haven't addressed the nearly shot hubs, engine mounting tab, or engine tensioning bracket (clevis). Add to the list frame gusseting and re-welding. I started out calling this thing the SBox in reference to it being a POS (sh**box). That really isn't all that far from the truth it turns out. A couple more days of labor, though, and I'll have one fine machine!

I did a night ride with the teens last weekend. Got completely covered in mud. I was riding in some tall stuff and the chain started jumping the sprocket badly. Spent 5 minutes clearing this out -



Any tips on how to prevent this?

I didn't spend 30 seconds total in the messy stuff but I still got covered.



My DIY header turned out a lot better than I expected. I bent with a torch, sand, vise, and an old rim.



This isn't my final mounting location or solution - Just a mockup. I moved the can up and closer to the engine.



The can is $14 off ebay. It is way too loud for my liking. I haven't done any plug tests yet. I've got a 130 main in the 30mm pumper carb at the moment. I did do a short run just to see how loud it was. It is as fast top end as it was with the stock can but it is lacking power dearly in the low rpms compared to stock.

[Pripyat]

I wasnt confident in my readings using used plugs for the plug chops. I bought six NGK plugs for less than $20 to cut up. I ran a test with the 130 but it was so obviously lean I didn't even cut it. I threw in the largest jet that came in either assortment (140) and ran the test. I rode about a mile down the road to a straight about 500 yards long. Pulled over, installed new plug, ran WOT for 500 yards, killed engine and stopped buggy as quickly as possible.

140 is a wee bit lean :/


I'm debating drilling out the second 140 I have so I can ride this weekend while I wait on larger jets to come in the mail.

[EDIT] I drilled out the extra 140 main I had to 1/16" and stuck it in. It was definitely rich. Bogged like crazy anything over 3/4 throttle. I was originally concerned that it was a float or other similar issue but at least I can get the buggy to run rich if I want to.

What I did find strange is that when I went to swap the jets the gas tank was under vacuum. It was actually deformed and air rushed in when I cracked the cap. This doesn't seem right and may explain the excessive lean scenario I was experiencing with the 140 main. I think if I can figure out what is going on with my gas cap I'll be getting somewhere.

[ckau]

Originally Posted by Pripyat

What I did find strange is that when I went to swap the jets the gas tank was under vacuum. It was actually deformed and air rushed in when I cracked the cap. This doesn't seem right and may explain the excessive lean scenario I was experiencing with the 140 main. I think if I can figure out what is going on with my gas cap I'll be getting somewhere.

If you haven't already.. go up to 5/16 or better on your fuel line and a high volume fuel filter. You'll find the 30mm will use gas faster than the stock 1/4 can deliver.

[Pripyat]

So maybe buggies aren't for me..



The teens were riding earlier so I joined them. I'm really not sure what happened. Went around a turn around 30mph expecting the back end to slide but it didn't. No warning at all. Went right over. I know better but instinct got the best of me and I reached out at the ground trying to break my fall. Right as I realized my error it was too late.. fortunately I've just got a sprained thumb and a bruised elbow. After the initial roll I crossed my arms and was fine. Safety harness did a great job.





Add that to the list..

[SYCARMS]

Glad to hear just bumps and bruises. Several years back at Bash. At only about 15 mph I had to steer around a huge rock probably 2" high. As we went around it my right tire hit a 6"- 8" high 6" dia stump, the steering wheel almost took my thumb off forcing my arm out side of buggy as were rolling over. I got my arm back in, those just behind me said they were sure my arm was getting broken and crushed and couldn't believe I got it in just in time. The two years prior one from our group and someone on a 4 wheeler, one has broken wrist and the other a broken arm, same spot. Since that time I have only 5 Pt harnesses and arm restraints on all my buggies.

[Pripyat]

Now I'm second guessing myself..

My infatuation with buggies is because I've never had one. ATVs and dirt bikes have been a huge part of my life since I was a kid. But never buggies. I can't get over how quickly the roll occurred. I've gone that fast around sharper turns without issue over the last couple weeks.

About 200 yards before the rollover I hit a washout on the left side of the buggy. It was an extremely hard hit. I remember feeling the force on my shoulder straps and being thankful I had those big straps to hold me in. I was actually surprised nothing broke.

I guess I'll never know for sure but there is a real possibility that the rod end failed and caused the roll, not vice versa. Lol who am I kidding. I was probably just going too fast.

[neo71665]

Looks like a cast heim. I've learnt the hard way leave them alone in my old drag truck.

[Pripyat]

Anyone have a suggestion of a better rod end? Summit racing has 145 1/2-20 RH rod ends to choose from.. they've got low carbon steel, carbon steel, alloy, chromoly, stainless,..

[neo71665]

I used to like Aurora heims (good enough for the nasa and the military). They actually aint priced bad, real good quality, and tons of options

http://www.aurorabearing.com/

This place used to have the best prices on them but it's been awhile since I've shopped around.

http://www.midwestcontrol.com/

On the a-arms I would pony up for chrome moly. Something like that I don't think there is such a thing as overkill.

[ckau]

Originally Posted by Pripyat

Anyone have a suggestion of a better rod end? Summit racing has 145 1/2-20 RH rod ends to choose from.. they've got low carbon steel, carbon steel, alloy, chromoly, stainless,..

take a look at these guys.. QS components Inc.

https://www.qscomponents.com
I've used these guys for quite some time. Good folks to do business with. Never had the first issue with any of their products. I've had numerous roll-overs, flips and carnage. After post incident inspections where one would expect to see heim damage there was none. I recently replaced a set of heims on one of my yerfs that were over 10 years old. Not because they were failing... I simply figured they got to be past due.

[x-bird]

I've used the auroras and the midwest, for the price and customer service I'm very loyal to midwest.

[Pripyat]

I'm wanting to order rod ends by tomorrow. I already want some frame gussets from Jeg's (linked earlier in thread) so I figured I'd get my rod ends from them as well. Unless steered otherwise I'm going to go with one of the two pictured - ALL58058 or Jeg's 64125. I'm going to go ahead and order enough to replace all my rod ends and keep the ebay economy trash ones as spares.

[SYCARMS]

Heims have many uses, steering heims are much stronger. At the very least I would give JEGS a call to make sure they are rated for steering use otherwise follow CKAU's lead. I went with heims as mt tie rods and paid somewhere in the area of 40.00 for 2.

[Pripyat]

Originally Posted by ckau

take a look at these guys.. QS components Inc.

I missed this post somehow -

The rod ends that failed were from QS Components. They were the economy panhard kit that they sell on their ebay marketplace. Username QSC8.

I just emailed them a picture of the failure and asked them to give me a call to discuss. I'm assuming they will tell me to buy the chromoly ends they sell.

The rod ends you have had good luck with - Were they the regular economy or chromoly? Based on their website the economy are $22 and the chromoly are $36 for bung+rodend+nut.

[neo71665]

A panhard bar only really sees load force in a lateral direction with the joint. You might be able to use lower quality heims there and get by for awhile. Having them hanging out over the end of an a-arm like that they see forces in every direction. The steering ones mentioned will have extra bracing ribs in the joint body and/or be larger (not to mention not cast on quality ones).

IMHO 1/2 inch is too small. Just by looking and judging I wouldn't suggest any smaller than 5/8 and push 3/4. My experience is more towards automotive but I've been in a bad wreck because of suspension failure so I tend to lean towards gross overkill. Since you already have 1/2 inch bungs welded in I would go for the highest rated ones you can find. A $100 heim joint bill now is cheaper than a few grand hospital bill later.


As for the brackets, gussets, and such you might want to see if you have any local welding shops. I have been getting mine cut locally for years at a fraction of what I can find them anywhere online. Get them any thickness or design I need in a matter of minutes. If I win a lotto a cnc plasma table is the #2 thing on the list of things I'm buying.

[Pripyat]

I'm torn regarding the rod end strength. If they were much stronger I'm guessing I would be looking at a much more intensive repair. I was inspecting the buggy for damage over the weekend and found this on the upper front control arm on the side with the broken rod end.



Spindle also bent -



I have seen sheer values as low as 6000 for 1/2" economy mild steel heim joints and as high as 18000 for alloy ones. I wonder if the control arm would have broken if I had top-of-the-line rod ends. Part of spec'ing rod ends is determining what you want to break first - the rod ends or other suspension components. I'm honestly not sure which I would prefer. I'm eager to hear back from Jeg's and QS as I have messaged them both with the application.

One other question - Would it make sense to rework the mounting holes on the spindles so the lower rod end isn't extended so far? Or would that mess up my steering geometry?

With my upper all the way in this is my lower to get a couple degrees camber -

[SYCARMS]

My ends are chrome molly. I've known many who changed to heims only to fail. The proper heim joints are designed for steering components. The main difference is in the metal used. The stronger the metal the more expensive. The heims you have that broke will work just fine on a conveyor system, but no where adequate for steering/suspension. E-bay is a wonderful site but as I've stated time and time most of these people just sell for profit and know nothing about the product so it is buyer beware. Products produced with quality control will cost more due to the people and practices involved as compared to a non quality controlled part. I would go with the chrome molly ends over the economy. If you just run on the streets I would go with the economy but off road is so much more abuse to the steering /suspension systems.

[ckau]

From the pic it appears your spindle is incorrectly installed. The pic shows the heim on the underside of the spindle where as it should be mounted on the upper side of the spindle mount plate. Both lower and upper A-arms should be on the upper sides. You want the spindle to push up against the a-arm rather than pull the arm up during suspension compression. this may explain the heim failure? That is a lot of extension on that heim to achieve camber. I wonder if your dealing with unequal a-arms? With my upper heim turned completely in, about two turns on the bottom give me aprox. 3 degrees of camber.

[Pripyat]

I definitely have them mounted incorrectly. I remember wondering why the control arms were wider at the spindle. That still doesn't explain the heim failure, though. The upper failed which was screwed all the way in.

No need to modify the spindle like I mentioned earlier. I just need to move the lower rod end as ckau described.

Im a little disappointed in both Jeg's and QSC. I sent both a message with pictures and I haven't heard back from either of them. I at least expected to hear from QSC as I sent photos of the failure.

[neo71665]

Originally Posted by SYCARMS

most of these people just sell for profit and know nothing about the product so it is buyer beware.

*cough*summit&jegs*cough*


Both of them are just resellers. They are only gonna spout off what they know and written on the website. If you want real useful info your best bet is to email the actual manufacturer of the part. https://www.allstarperformance.com/

Never dealt with QS and I have no clue about them


As for companies replying to emails, I'll have to stand up for them as a former business owner. Remember it's monday, they most likely took the weekend off and now trying to catch up with every email sent from 5pm friday to 6 am monday. Even if only 3/32 of everybody in North America emailed them a question all the replies they have to make. I was just a small shop and can remember spending 4 hours on a monday returning just weekend calls and emails.

[Pripyat]

OK so I got some replies -

AllStar -

Thank you for your email inquiry. While we do not have much experience in the go-kart segment our Moly rod ends are typically the best and most popular to use on a suspension application, used on almost exclusively on dirt modified and late models. Our part numbers are ALL58058 and ALL58059.

Jeg's -

These guys here are one of the best rod ends we carry here 122-XMR8, there are some stronger one but I do not think you will bend or break these guys.

FK -
I originally sent ckau's picture for the application since mine is still assembled incorrectly. I mentioned I had a failure on the QSC economy rod end and wanted to upgrade. He noticed that ckau has chromoly ends and not economy and was confused at first. After I sent him pictures of the failure I got this -

OK, that helps a lot! The rod ends in the first picture appeared to be the higher strength chromoly units. The broken one you just sent me pictures of are indeed their economy low carbon steel units.
I think you simply had lower strength units. “Might” have been OK under normal use, but the crash might have been too much for it. Not sure how bad the accident was, so it’s hard to say. It’s possible they were too light for normal use too. Definitely was a sheer force, which could have been from normal use or from the accident. I’d say you’re going to want to go with a high quality 3-piece style in chromoly like what is shown on the first picture you sent to me.
I’d say check out the JMX8T for the RH thread and JMXL8T for left hand then. You can find them on our website at: http://fkrodends.com/JMXJMXL15.html. These would be quite a bit stronger than what you had originally.
We offer basically the same economy version as well for lighter applications. Our economy version in ½” is rated at 8,386 lbs. and the JMX8T is rated at 16,242 lbs., so it’s a pretty substantial difference.
Also, the JMX8T features a self-lubricating PTFE liner, so you won’t have to keep greasing them. It also helps keep dirt out of the space between the ball and the race. I’m willing to bet the ones you had on there were just metal to metal.

Still haven't heard anything from QSC. I also messaged summit since why not..

[Pripyat]

OK so I'm hoping you guys can help me out -

Several things have happened over the last month that have me completely re-evaluating what I've done to the buggy. It is harsh realization when you find yourself having more fun on a 110cc kart designed for a 8 year old than your own custom buggy. The 110cc slides all over the place and is absolutely loads of fun. I get this stupid grin on my face and it is just awesome.

So now I'm looking into lowering the SBox and keeping the suspension components. Once the lowering is done I'll likely drop down to 20s on the rear.

What I need help with is the math behind changing the shock mounts on the rear of the buggy. We will address the front later. The 14" blaster shock seems very stiff so I was planning to change the mechanical advantage of the swingarm pivot while also lowering the pivot point at least an inch. I measured all the angles and drew it up. Anyone want to chime in before I have to pull out my old statics book? Mainly, which point should be moved, or both?



Whatever you guys recommend I can throw in autocad and give you the drop values and such. FYI moving the upper mount up 1" yielded a drop of .89".

[Pripyat]

I really wanted to get the FK ends but I couldn't bring myself to pay $22x4 plus shipping. I found some 2-piece chromoly ends rated at the same shear strength, PTFE lined for 22 a pair. Eager to swap out the economy ends and get the lower control arm to spindle mount corrected.

I was about to rework the engine mount tab and had an idea. Would this at least keep the thing from failing? Assuming I welded it up..

[x-bird]

you're actually going to want to raise the swingarm and shock mounts on the frame to drop the frame/ride height. Making that move will then lead to engine clearance concerns on the rearward rake of the rear frame and cargo rack area when the swingarm goes into compression. Moving just the shock mounts will accomplish the same thing, but change the platform angle in relation to the ground so carb and clearance concerns doing that.

While your at repair stage with the front end, I would recommend eliminating the single shear installation design. Get 5/8ths ends and high misalignment spacers and make it double shear paired vertical mount plates on your spindle pivot points and steering arm and get vertical support on that arm. With the spacers you will have enough turning radius and will eliminate any chance of bind at the spindle side. your suspension travel will then be limited by the steering rack connection to the tie rod. Also working a new bung into the end of the lower arm to add about 3/4" of length and putting it on an angle close to parallel to the ground at loaded ride height will help matters. gusset the corner of the arms where the crack is.

swingarm brace is a good plan/location, but a piece of 1" tubing would be stronger than the angle iron.

[OLDKID]

Lowered Suspension ? Smaller Tires ? BLASPHEMY I SAY !!!

[x-bird]

Originally Posted by OLDKID

Lowered Suspension ? Smaller Tires ? BLASPHEMY I SAY !!!

I need to do the same to my daughter's ride. shorter shocks and smaller tires, she's essentially racing rough dirt flat track and the tall tires, higher cg and slower acceleration rate aren't a good match. Have even though of putting a tube shaft in place of the shocks.

[Pripyat]

Yeah this is very abnormal for me. I have oversize tires on every vehicle in the arsenal. To be honest the buggy lost a lot of its fun factor when I rolled it. When a vehicle no longer slides in the turns there is a problem.

One thing I'd love some input on - I rolled towards the drivers side. Both front and rear wheels on that side are packed with dirt in the bead. Is this typical or could this indicate I'm not running enough air pressure? I can't remember what pressure I'm running on the rear but it is less than 5psi on the 22s.

[Edit] Anyone know the compressed length of a blaster front shock?

[ckau]

I'm probably a day late, Pripyat moves quickly.but to put my 2 cents in... altering the shock points is not a good idea to lower the suspension. It effects the motor position and can effectively upset the float bowl settings. Plus reducing suspension travel. you wouldn't want the head striking the back of your seat. Fabbing some shackles to raise the swing arm pivot point is the way to go. Also shackles for the shock points too. This allows for experimentation of position with the option of returning to stock. Using a smaller diameter rear tire will alter the final gear ratio to give good pull out of tight turns with the ability to do the drift thing but overall lap times and top speed are greatly reduced. A tire with less aggressive tread pattern will accomplish the drift action without topping out motor rpms .This is a set of Duro's designed for flat track and TT courses. this is a set of 20's, the tallest their offered. Can't beat them in tight turns but couldn't keep up on the straights.

[Pripyat]

Originally Posted by ckau

Pripyat moves quickly.

Sorry - when time and circumstances allow I try to get as much done as possible. I value your opinion and feedback - PM me your cell number and I'll text you when I post about suspension related issues.

I spent the weekend at Disney. Would have rather been home piddling. Not sure what that means.

There are two reasons I want to lower the buggy - lower COG, and the fact that I've already heavily altered the angle the engine sits. Filling the engine with oil takes forever unless I raise the back end first.

I did some pondering about the shock mounts. My understanding is that if I want to change the mechanical advantage of the shock I would have to move the mount on the swingarm. To have the shock seem softer I would have to move it closer to the swingarm pivot. Which would mean that the mount on the frame would have to move up.. a lot.

Once I figure out the compressed length of the blaster shocks I'll revisit and determine what makes the most sense.

[edit] Those tires look like a lot of fun. If I keep the buggy long-term I can see myself having two sets of wheels - One set for keeping up with the ATVs (22" knobbys for obstacles and mud, slicker 20s for fun). I already have some concerns about all the damage I'm going to do to the fields I ride in trying to slide with those huge knobbys I have on there now. I don't see an option in the tire you referenced for a stock 8" rim, though. I really need to work on sourcing my aluminum rear wheels so I can get new hubs and have more tire options..

[x-bird]

dirt in the bead is "normal" when you've essentially bottomed or max loaded without bottoming the suspension then also used up the tire's sidewall "roll". the tires are low pressure and in softer soils you will get dirt in the bead during cornering more than u will on hardpack.

you are correct in your thoughts about the shock move and what you'll have to do and its effects. but also remember that you move the loading point with the shock so you will have to beef up the swingarm to counter that. such a move will also increase the distance up/forward that the swingarm can travel even with a raised lower mount.

[Pripyat]

Buggy took one heck of a hit..



Not sure if I'll try to repair or replace..

[tim]

I have the same problem with tearing up grandparents yard.I thought about going back to four of these golf cart wheels and tires.i can find them cheap off of stock carts and they have little side bite and shorter as well ,i have 4/4 all the way around so I can use old rims also.not sure about offset will have to check on that.

[Pripyat]

I completely forgot I have a set of stock 20", on rims, from the trash buggy. As soon as work slows down ill swap them on. Should be loads of fun as they only have maybe 50% tread.

Still need to gusset the control arm. It bent back nicely. Hydraulic control arm bender:

[Pripyat]

This has come up already but I'm ready to start sourcing the parts for the axle/hub upgrade. I know my rear hubs are about to start spinning on the nearly non-existent splines. I've been searching desperately for any aluminum quad wheels but may end up getting them from ebay. I found a local guy with an entire set with new holeshots from a LTR but he wants 300 for the set. Unfortunately I would be paying for tires I don't want - Fronts are 20x6x10 with 4/144, Rears are 18x10x8 with 4/110. I need 18 or 19 fronts, 20 rears. Sigh.

I still plan on lowering the buggy suspension at least an inch at both the front and rear. I like what ckau did with his front shock mounts. I expect I will just move the upper mount up and out around an inch, giving a wider stance on the front and slightly lower COG.

What is the cheapest option for the axle upgrade? I haven't done much research yet but the kits look expensive and I'd rather throw something together from parts than buying something already pieced together.

[edit] I almost forgot - I think I broke a tooth in the steering rack when I crashed. I was moving the buggy yesterday and noticed that there was a "clunk" in the rack/steering any time I was turning the wheel under load. It only clunked one time per full steering travel. It's hard to believe one of those hardened teeth broke. I'll have some time to investigate maybe this weekend.

[Pripyat]

Buggy hasn't moved since the crash. Hopefully I'll at least get it mobile in the next week.

I caught heck getting the sheared rod end out the bung on the upper control arm. I welded a 1/2" nut onto the protruding thread to aid in removal. My 200ft*lb cordless impact wrench that wouldn't budge it. It took a few minutes for my 1200ft*lb pneumatic impact to get it out. Every 15 seconds or go I would stop because it would start smoking the oil off..



I'm really not sure why that happened. The threads look great up until the area that was protruding past the bung when it was screwed all the way in. I ordered new bungs just to be sure. I have LH 1/2-20 tap so I may just chase the non-existent threads so I can at least move the buggy. It will take a lot of time to remove the existing bung for replacing.

My spindle took a good bit of damage as well - 5/8" grade 8 axle bolt stood up fine but the steel plate was bent and torn.



Bending it back really didn't make sense so I cut it off and will weld a plate back on.

[tim]

Not sure how to ask this question,I know these are not stock cars but we always built a soft or crushable cage and braces in front of the motor mounts so a hard hit would not destroy the subframe and the bumper would crush and save $$$$ parts.Has any seen buggies built to protect front-end and still look good.
Thanks

[SYCARMS]

I own a Blade single seat, 2 Joyners = 250 &650, single seat Challenger and a Yerf. I ride these pretty hard and have only bent control arms and a rear axle on one from some pretty good hits all since 2004. In my opinion all these mentioned buggies were designed well with exception of the Yerf Dog while understanding that the Yerf was originally designed as a yard cart unlike the other mentioned were better designed for off road use. I have known people who have bent A-arms and built some much heavier arms only to destroy the next component in line. Many think that by bullet proofing one part they solved the problem in which they are correct kind of, however that part may hold up but something else is going to give. You want the most accessible and cheapest parts to fail. Comparing the other 3 buggies mentioned to the Yerf Dog and one can easily see why the Yerf in stock configuration is so inferior to hits. The only positive to the Yerf is it is much lighter than even my 150 and 250 single seater buggies. Bottom line is when altering these buggies one must have some engineering knowledge or consult with someone who does.

[tim]

Yeah I know i had some unproven Redneck engineering using an old rocker arm pivot and grade two nut trying to make a weak point just in case a tree jumped out in front of me.I went back to just a grade five nut now that my son is old enough to drive,but I think this may be an area we can use something that will bend not break to absorb some of the force.Hey Pripyat are your tie rods aluminum that's something else I thought might help save $$$ in the long run.

[x-bird]

for awhile i used aluminum rod stock and made my own through bolts for the steering arm to tie rod connection. cut to length and cut my own threads. It worked well in theory, but on the race course they were just not strong enough and failed too often. After that idea I made modified shock tie rods, essentially rubber bushed internals on 1/2 of shock body. I still use them and regularly see where they take close to 1/2 inch of impact travel. I'm on my second set of bushings inside them after 4 seasons of racing i think. I did crack a steering arm off the spindle last race of the season year before last, but it let go at a spot where I'd ground the weld back too much--lost only the weld-- and i also had a flat on that side, don't know which came first.

[Pripyat]

I'm finally getting a little confidence in my welding and am beginning to go rogue to some extent with my modifications. To bulk up the engine mount tab I went across with some angle. I considered using tube but due to the triangle braces at each end the tube would have been much more difficult to cut-to-fit. Or it would have had to have been closer towards the front of the buggy which I didn't want.



Doesn't look bad painted up.


I despised how the blaster shocks on the rear had the engine tilted at such an extreme angle. Last time I changed the oil I put the rear wheels on drive-on ramps and still had a hard time due to the oil pooling at the fill tube. I'm not sure how much this changed things but I'm already happier with the lowered stance.



Cut the upper rear shock mounts off and moved them up.


Here I had just welded and was looking to see what impact the change made.


As far as the jacked up spindle I beat out the minor bends and welded up a plate to replace the torn upper piece pictured earlier in the thread.



As far as the front I got really bothered looking at how the control arms were at such an extreme angle due to the longer shocks. I'm interested to get feedback since I did this on a whim..

Popped new holes.



Cut a hole for clearance.



Cleaned it up.


I got to looking and really didn't feel comfortable with how much material I had removed so I beefed them up.

Welded 1/8" plate on either side.


While I was at it I welded little gussets in at the bulkhead mount tab. Between these and all the other weld I added I think it will be fine.


Also added nuts to the control arms for zerk fittings. I had drilled/tapped before but I wasn't comfortable with such little thread engagement.


And lastly.. the new stance.

[OLDKID]

I like it ... I LIKE IT ALOT !

[Pripyat]

I was wondering if low air pressure aided in the buggy flipping. I was running 2.5psi in the rear and 10psi in the front when the rollover occurred. As a test I took both the front and rear up to 15psi. The ride is absolutely horrendous. I'm going to back off some at least on the rear tire pressure but I'm not sure how much is reasonable.

I also plan to test with the stock tires I've got but I'm expecting that considering they will have less sidewall I'm going to prefer the ride of the 22s.

[SYCARMS]

5psi front 7psi rear

[Pripyat]

I'll try out those pressures.

I'm finally back to carb tuning - I have the largest main in the carb currently, I believe it is a 140. It doesn't take throttle well when the engine is mid-range. If I'm going slow it is super sensitive to changes in throttle position as it should be. But if I'm running 15 or 20 and quickly open the throttle it bogs a little. More than it did with the smaller main. I also get backfiring/popping on decel.

But, I did a plug chop and at WOT it is lean.


The plug I am running in the buggy currently (that I pulled out when I was ready to run the plug chop test) shows signs of both rich and lean conditions IMO.



This makes me wonder if I'm rich down low but lean top end. Perhaps the lack of backpressure due to the DIY header has something to do with it? I'm open to suggestions.

[Pripyat]

The jet assortment posted earlier in the thread only goes up to a 140 main. I can't find an assortment that goes up to 150 that also includes the pilot jets. Regardless I just ordered another assortment of mains that includes 145 and 150. I'm hoping that one of those two will get me where I need to be at WOT.

It is the teen's spring break. I'm going to post up a video and I'm hoping you guys can go by sound and give me some feedback regarding the mid-range bogging I'm getting with the 140 currently.

[SYCARMS]

I have mains up to 165 but you shouldn't be anywhere around 140 main.

[Pripyat]

Then why is my plug chop indicating lean?

Remember that a while back I drilled out a main with a tiny drill bit to run a test to see if the carb bowl was starving for fuel. I couldn't even get the buggy out the yard it ran so poorly. Also when I first started testing I tried raising the float and that didn't affect anything at all, either. I raised it maybe 1/8" and did a speed run. Top speed was unchanged.

Like I said before.. I'm open to suggestions.

[SYCARMS]

Have you checked for vacuum leak at intake? What carb are you using? stock or other?

[Pripyat]

I have checked for vacuum leaks - both with propane and carb cleaner. The buggy runs alright the way it is currently but occasionally, I haven't figured out how to recreate the scenario perfectly, it wants to hesitate and sputter when throttle is applied. I'm pretty sure this is with the 140. I'm going to feel like an idiot when I realize I changed the main weeks ago just before the crash and forgot..

30mm pumper carb, 6" intake tube, UNI, straight-through muffler with maybe 13" of 1" ID header.

Here is a video of the buggy as it sits.
Video

I did go through the fuel lines and they are all oversized and wide open. I also messed with the gas cap and basically removed the check valve to ensure a vacuum in the gas tank was not causing issues.

[SYCARMS]

That 30mm carb is too big for that engine. This is why you are showing lean with 140 jet. Your engine is like a vacuum. With the proper carb and jetting the volume of air being sucked through carb creates a negative pressure thus sucking the fuel up through the main jet. The 26mm carb with correct size jet will provide the engine with proper fuel at higher rpm. Compare what you have to a vacuum. You have a 5 HP shop vac with a 1 1/2" diameter hose and it will suck up a 3/4" x 2" bolt no problem but put a 3" hose on that vacuum and it won't suck up a 1/2" diameter rock. Go back to the stock carb and properly jetted you will have more power.

[Pripyat]

I have plenty of stock carbs lying around. I can do that test and report back.

If you are correct and the velocity of the air through the carb is not high enough to draw enough fuel through the large main at WOT does this also explain the bogging at mid throttle? Why am I rich low end and lean top end? Is more velocity required at WOT or is it an issue with decreased vacuum due to the butterfly being open entirely?

Also, if I throw the stock wheels and gearing on and do a speed run would this be good indicator of how my engine is performing top end?

[SYCARMS]

At idle the fuel is pulled up using engine vacuum the main jet circuit uses the vacuum or negative pressure of air pulled through venturi. If too large carb is used the negative pressure is reduced which is why larger jets have to be used to compensate the lack of neg. pressure. Not only do you run lean at WOT, the transition from idle jet to main jet will be weak causing a flat spot. Make sure your stock carb is clean leaving the .38 pilot jet in and increase the main jet to a 125 than do a WOT run and check plug. Now as I said use an old already colored plug when doing this check. Pay attention to the ceramic and rim of threads for color, no need to cut up plug to check. One run will change the color of plug but it has to be an already used colored plug. Once you determine the proper main jet @ WOT than you will adjust if necessary the pilot jet. The smaller the sprocket the more top end, the larger the sprocket the more low end. The larger the tire the more top end the smaller the tire the more low end. Work on one thing at a time so you can determine the changes made from that particular adjustment. More than one change at a time and you cannot determine what caused what change.

[Pripyat]

It has been a little while.. Since my last post I've adopted a little girl, switched jobs, and built a house on my 45 acre lot. I've got so much room for activities. Shop is next on the list but in the meantime I started messing with the buggy again.

I pulled the oversized knobbies off the back and put some stock tires on. The buggy is so much more fun without all that traction. Before, in turns, the buggy wanted to lean. Inside rear tire always wanted to grip and roll. Not a problem now. I kept spinning out in turns after the swap. Such a great feeling when you get that perfect drift on a sharp turn.

Anyway, back to the carburetor - My intake boot tore on the stock carb so I stuck the big CV carb back on. I have been wanting to play with it ever since I couldn't get it to run right a while back.

I was curious to see if I could get the thing to idle right. I changed the angle of the carb by changing the engine mount bolt. I got it a lot more level which makes me feel better but didn't seem to change much. I tried a couple different sizes of pilot jets and couldn't get anything to work quite right. It would idle fast but wouldn't drop down to a slow idle rpm. On the third jet I can't remember what I was doing but I backed the screw out a LOT. What I found is that I can get the buggy to idle beautifully if I nearly remove the adjustment screw on the side of the carb. I can't remember if this is a fuel or an air screw, I was hoping someone on here could explain why this would make sense. I ended up with a 125 main. Buggy runs fine but it isn't quite right. After a long decel the engine doesn't want to take throttle again. I'm assuming that is because my pilot jet is probably way too large (I was testing 2 sizes larger than I had originally when I realized that backing out the screw allowed the buggy to idle). Thoughts?

[Pripyat]

posted twice, can be deleted.

[Pripyat]

This is going to require at least two posts, you may want to give me a day or two to get the second half of the data together before replying, unless you want to guess what the results are.

So I had to figure out why exactly I couldn't get the 30mm carburetor to run right. First off was the idle. I sent a picture of the carb intake to a buddy of mine and he commented that the slide travel was being restricted by something.



Based on earlier conversation, this carb is likely too large for my application, so I didn't see why allowing the slide to go lower would be a problem if I already had an idle issue.



There was a ridge along the edge that was keeping the slide partially raised. It would be easy enough to add back later so I ground it off.



Afterwards the slide nearly came to rest in the bottom of its slot.



Started up the buggy and for the first time I was able to adjust the mixture screw and get a steady idle. This change I am quite happy with and it hasn't given any issue over the hour or two I've put on the engine since the modification. Idle is the least of my concerns now. Next up is trying to figure out how to get a richer condition at WOT. Previously I posted that, even with a large main, I was still lean WOT.

The issue had to be one of two things - Either the slide was not coming up far enough at WOT to sufficiently get the needle out the way of the main jet, or the slide was opening up sufficiently but the air velocity was not fast enough to draw enough fuel from the venturi. I did a ton of testing with data logging and think I've finally figured it out.

[Chief240]

Is anyone still on this post? I’ve got a spiderbox I’m building and running into similar issues and solutions.

[SYCARMS]

What are your issues?

[Pripyat]

I finally put my new keyed axle and new bearings onto the buggy. I used the same axle ckau used, 42" keyed, drop down to 3/4". I planned on adding a second set of hangers but decided to just use the existing hangers for now.





I also picked up some Z400 rims for the rear although I am not happy with the current hub solution. Granted, it is all over-the-shelf, no fabricating. (It has an adapter). I'll post up some parts and pics later on. I have a lot I need to get onto this thread..

My problem - The axle is unbelievably bendy. If I apply pressure to both sides of the chain between the sprockets (causing the chain to pull more on the sprockets) I can watch the wheels move from the bowing/flex of the axle. I can set my chain tension to the point where there effectively is no slack and am still popping the chain off when conditions are right (under load, coming out of a hard right hand turn). I know ckau built "boxes", I honestly am debating trashing the entire thing and going with a 1.25" axle. I will find something to do with the other one eventually. Still, I'm not sure 1.25" would be rigid enough.

Any other thoughts? I debated trying to add a bearing near the center of the axle but that would make it near impossible to get the engine out the swingarm. I'm curious how wide my "boxes" would have to be, if I could just add a hanger to the inside of the swingarm on both sides and that may be enough? I'm sick about this entire thing, I had the same chain-popping problem before the axle swap as well.

[edit]
I decided to try and add a center bearing since I already have the square tube across the bottom rear of the swingarm. I was working on getting it in place and realized that the axle was already warped. I pulled the axle out and stuck it on jack stands and a couple swings later have it nearly perfect. There's well under 1mm of movement at the sprocket so I'm going to use the current axle to place my center hanger and test function.

Axle straightening


Here is what I was about to weld in -


I honestly doubt this will be rigid enough, It may keep the axle flex down enough to keep the chain on but I'll likely end up with stress cracks at the welds over time (uneducated guess). I could always replace or beef up the square tubing pictured above.

More bearings and hangers are on order. The stock bearing ID is 1mm too small to use in the meantime.

[edit] I contacted Azusa, I asked what the difference was between their standard axle and the flex-proof. I also sent them this post and asked if they had any suggestions. Their reply -

To address your questions: A 1" OD Flex-Pruf Axle or Standard Axle using 1" ID Insert Bearings, properly enclosed in flangettes (allowing the bearings to rotate under radial and axial loads) should perform well.

Both the tensile strengths and yield strengths on all Azusa axles are more than sufficient for the application. Flex-Pruf axles are higher strength than the standard steel, but the term "Flex" has nothing to do with its specifications.
It is simply an in-house marketing term used to differentiate between the two axle classes, and created because it did not infringe on any steel producers' brand or trademarked names.

The principal reason chains are thrown off is because of misalignment between the engine (clutch) sprocket and the axle sprocket. Both sprockets must be perpendicular to their shafts and lie in the same plane.
(A straight edge placed on the face of each sprocket would lie in a plane parallel to the center-line of the kart.)

All Azusa steel axles have comparable rigidity values. Although metals in general have a wide range of rigidity, the Modulus of Rigidity for all steels varies less than 8% - ranging from cast steel to high carbon heat-treated steels. Though Flex-Pruf axles are about 60% higher in both tensile strength (TS) and yield strength (YS), neither value is as important as mechanical design and weight distribution. Mounted on a standard kart frame the axles work fine. Your application may be pushing a 1" diameter axle to it's limits with the wide tires extending the length of unsupported axle beyond the frame bearing hangers.
Supporting the extended axle is one option (or) using a tubular 1-1/4" OD axle would be an alternative but would require a re-design.

My sprockets are aligned at rest..