Spiderbox Project Thread

[Pripyat]

I started this thread over at DIYGoKarts but I'm getting little to no feedback so I'm moving over here. Hoping to get some useful feedback.

I picked up a spiderbox (I don't even know which model) on a trade. Had been sitting in the weather for a year but supposedly ran when it was parked.


Ball joints were held on by a washer tack-welded in place..


Rear tires were shot, wheels should have been trashed. I cleaned them up best I could and coated them in rustoleum. Had to move the valve stems as tubes were installed.


I installed heims to replace the ball joint issue. Felt good to cut that trash off.



Drilled 7/8" holes with drill press for heim install.






Waiting for paint to cure to install grease fittings.

I didn't think I would ever get the bolts and rods out the control arm bushings. They were pretty badly corroded and had to be hammered out. The bolts were actually warped. As they rotated the entire control arm gyrated.


After a soak in the ultrasonic cleaner:


In case anyone is curious the lower ones were the most corroded. I've since cleaned up the rods and have all new grade 8 hardware awaiting reassembly.

Passenger side hub was severely seized. Had to be pulled, heated, and beaten simultaneously to get it loose.




I have 22s for the rear and 19s for the front. Blaster front shocks for the rear. Up front I'm still deciding if I really want 3" of added ground clearance you get from the higher end pre-made solutions. I've got the BD hubs for the front wheels.

I added 2" spacers on the rear but I'm going to drop down to 1" after reading some posts on here about axle failure. Going to ride on the stock axle setup for the time being, until something fails.

I did come up with a fairly cheap intake solution. Enough hardware for two intakes (not including radiator clamps) plus the UNI filter for $27. I can post a parts list for anyone interested. The filter is 6", the tubing is the same diameter as the carb, 1.75". I ran the gearbox vent and crank vent to atmosphere with an inline filter.


Carb was absolute trash. Needle jet seized in seat, main jet broken from being overtightened.


I ordered a new one with a main jet assortment for $30.

That is my first question to you guys - I'm assuming the vacuum line from the intake downstream of the carb (goes to the side of the carb) is the fuel pump. On the new carb this port is plugged.


Do I need to get an external vacuum petcock or will gravity suffice?

[x-bird]

you're correct on the hose routing, provides intake pulse for fuel pull thru the carb to the tank petcock. rather odd to see that the new one is plugged. You could go to gravity feed with an on/off petcock. Will just have to make sure the gravity pressure doesn't overcome the float needle and flood it while sitting.

[Pripyat]

Your post got me curious. There is no diaphragm at all.



Are you guys welding mounting points for the 5 point harnesses or tying off to the frame?

[xlint89]

Welcome to the site.

Nice work you're doing for sure.

The original carb was a Constant Velocity type. The diaphragm wasn't a fuel pump. It helped the carb move the slide up as the engine RPM increased.

I think you just learned your first lesson about the cheap Chinese copied parts. THEY SUCK!!!!

Gravity feed is fine, no fuel pump needed. (I don't think Yerf came with fuel pumps) I'm running a Mikuni on my modified yerf with no problem.

While your working on the front end, might as well reinforce the "bulk head" up front. It's very common for that entire front end to break away from the frame.

Add the extra 2 teeth per side on the rack n pinion for better turning radius.

Good luck with your build

[GX150]

1. I went with 22” tires on the front and rear with original suspension geometry but upgraded shocks.

2. That new carburetor is a disgrace and the seller should be outed so others don’t fund the garbage he is selling.

[Pripyat]

Here's where I got the carb from:


Will this one work or do I need to go ahead and get another one on order? It is crazy that they ship a T and a vacuum hose to go to that fitting despite it being non functional..

[x-bird]

I'd report that to amazon and get my dollars back. and it shows the lucky of the draw with china parts. I'm a flat slide fan myself, a bit finicky on getting them dialed initially, but the bottom end response is much better than the round slides or CV types. cap the intake port, flat slide, gravity feed with a fuel shut-off,= kiss theory.

[Pripyat]

That carb works OK at idle but I havent even put it under load due to immediately disassembling the buggy.

I'm trying to spend as little as possible on the engine at the moment. It already has an exhaust stud issue. Previous owner drilled the stud but didnt tap for an insert.


Time-Sert kit will put me back $75. I epoxied a new stud in for now but expect it to fail soon.

I'm already regretting not replacing with a new predator. Unfortunately I seem to have the swingarm that requires more effort than just bolting in a 212cc predator engine.. That is a project for another day.

Anyone have pics of a 5 point harness install? I'm trying to determine what hardware I need. Shoulders can wrap around frame but I'm unsure where to go with the lap and crotch. I'm expecting to weld mounting points for laps (i dont want to wrap around frame that is exposed to exterior of vehicle) but still wouldn't know where to go with the crotch.

[tkeagle]

I have five points in mine. Can put in between the morning brackets on outside. Middle one I ran under seat, drilled holes in round tubing. Back ran behind seat. Under plate. And to round tubing. Had no issues. Been rolled many times. Held up fine. If I remember, I'll take some pics.
Heads up thou. The seat design sucks on them. Top straps will pinch the neck on smaller ppl, or kids. The slot on seat, is just one long one across. So nothing to keep them from sliding in on neck. Driver seat broke, replaced with better one. For passenger, took neck padding off my fl350. If recall right. Think drilled hole in the middle tubing between seats. Long enough bolt, and mounted both center straps to that. If recall right. Warning!!!
Always use lock washers or nylon nuts.
Don't know about other buggies. But these yerfdog will vibrate anything not locked down, one way or the other. Not talking just straps. Anything that using bolts and nuts holding anything together.
I'd go through the yerf. Anything that don't have either of these, add lock washer, or replace with nylon.
Especially the frame. Or roll cage.
Exception to this, might be engine area. Such as cvt case. But make sure those things are good and snug. They will vibrate out. But not so tight, u strip out.
Good idea to check all nuts and bolts many times during the year. Entire front end. A arms, ball joints, tie rods. Frame, engine mounts, roll cage.
Check it all. Might save you head aches, later down road.

[Pripyat]

OK so I think I've got everything under control. Harnesses and hardware on order. Updates in about 2 weeks.

Meanwhile I did do some research on the carburetor. The part is listed as an acv or air cut-off valve. One source states that the only difference between having one and plugging it is popping on decel. Apparently the vacuum during decel causes the carb to feed more fuel to eliminating popping. Looks like some people epoxy them anyway to make it easier to tune the carb on some dirtbikes.

The only thing left for me to buy is front shocks. There is tons of debate on the forum regarding this. Can someone talk me out of buying this? You've got 24 hours.



From BD.

Also - Do I need to do more to the front end than just adding gussets here?

[xlint89]

Can't comment on the shocks as I never tried them.

As for the front end, gussets there are good, but also add some steel to the front and back of the bulk head. The bolts can tear out the metal.

As for the exhaust stud, how about just retapping the hole for a SLIGHTLY larger stud?

If you're going to remove the head, go ahead and clean up the casting slag around the intake and exhaust ports. As well as port matching the intake and exhaust openings to the manifolds. Lots of free HP available through doing this.

[Pripyat]

Can I just weld around some .5" ID x 1.5" OD washers for the bulkhead? Would that be sufficient?

[tkeagle]

Some pics how mounted 5points. The front and 2 back straps, drilled and put bolts on the round tubing going under seat. Of course will need to remove seats to do so. For center ones, already a hole there. Just put long enough bolt to mount on each side. And outer ones, just use seat mount bracket bolt. At least is how I did it.

I did purchase the front lift kit upgrade from BD. To me, was money well spent. The shocks, not best, but very good upgrade. You can put a pre-load on them also.
I just had to buy new set of tie rod ends from them. Good upgrade as well.

Other pic is upgrade I did on bulkhead. 1/4 in plates in front and back of tabs that hold the A arms. Will need longer bolts. Think I got 8 inch grade 8 with nylon nuts off amazon. Don't need 8 inches. Think 7.5 will do. But with 8. Almost all threads are outside the pinch points.

If you are going this far. Look at BD, upgraded spindles, and ball joints. They have life time warranty. And they back there stuff up. If tight on money, would highly suggest the spindles first. They upgraded them lately. They good product.

[GX150]

I used 4-point belts and mounted the lower lap portion like TKEagle. The upper shoulder mounts went to the cage mounting bolts behind the seats

[xlint89]

If you hit anything with the front tire, you're going to wish you had something thicker than a washer. IMO I went with 1/4" on front and back of the bulk head. Same thing i used to make my gussetts out of.

TK, he's doing heims instead of the ball joints. MUCH better option I feel.

[Pripyat]

Thanks for the input, everyone. I've got some 1/8x1.5" steel on order for the bulkhead. Those pictures of the 5 point install were also very helpful. I was over-thinking and had plans to weld tabs for most of the attachment points. I now see that is unnecessary.

Work is going to prevent me from tinkering with the kart for the next week or so. Updates soon, though..

[tkeagle]

I seen that he was using those ball joints. Just didn't register. Think they look better. Didn't realize had to tap out and put insert in.
Seat belts. There are plenty of places to mount. Depending on how long they are. 5 points are nice. They keep you in place. They can a pain also. Alot of times we go out, its our kids, maybe few kids friends and adult friends. Alot of different sizes. Kids from 60 lbs, to adults 100 to over 200lbs. Got to adjust adjust belts every time change out drivers. Quick adjustments and quick release, comes in handy. Just guessing since you putting in 5 points, you got kids. No excuse for safety. But is a pain when 6 different ppl, are constantly getting in and out off buggy, and changing drivers.
Oh ya.. other thing I figured out. I non stop was touching up the paint on either side of the seats. Sometimes big chunchs. Thought was just rocks. But was in weird places. Then figured out, it was the 5 points doing it. Ppl hit the quick release. And throw the belts off them. The metal ends would slam on the tubing. Taking pieces of paint off. Especially the big piece that holds them all together. That one, is heavy, and took big chunks out. Like slapping a hammer down on the body.
Trying to get kids, to be easy when taking off belts. Bad habit to break, apparently.
I kept the original red powder coat paint on it. Put new paint over it, help with bond, and extra protection. The metal claps, will knock out chunks out of the powder coat. Not sure if high issue for you.
But I do like keeping mine, very clean. Not sure how to resolve this, other then changing bad habits.

[GX150]

Run split foam pipe insulation on the tubing where the belt hits or the entire length of the frame rail. The foam will still get chewed up but is cheap to replace.

[Pripyat]

What thread is the tie rod? Are both RH thread? I'm wanting to replace the tie rod ends with heims.

[tkeagle]

Yes, they right hand threads. Didn't know hemi had tie rod ends. Cool to know.

I did think about that. Might be easiest fix.

[ckau]

Heimed tie rods, ... 3/8 heims into 7/16 id rod. R&P end requires a little work. A u-bracket is fabbed with a 1/2-20 stud to thread into the stock R&p shaft. The spindles end uses a "standoff" to set tie rod at correct angle with swing arms along with high mis-alignment spacers.

[Pripyat]

Thanks ckau, that was helpful. I'm getting really frustrated by all the awesome threads on this forum with broken photo links so I really appreciate the photos.

I was originally wanting to try and spec the parts to get a heim on the existing tie rod but it makes more sense to beef up the tie rod at the same time.

Are your shocks the RFY variety? I want to go that route but have concerns about the strength of the lower mounting bracket. Most bad reviews I've read complain of major mechanical failure at that point. They seem like the way to go if you are willing to service the internals and drill/tap them for fluid changes.

[ckau]

Originally Posted by Pripyat

I was originally wanting to try and spec the parts to get a heim on the existing tie rod but it makes more sense to beef up the tie rod at the same time..

It's easier to make new tie rods I don't think bungs can be had to fit the smaller dia. stock rod. plus, the with heims and the R&P mount the tie rod is a touch longer.
Those are the RFY shocks. Original plan was to use those for fabbing the front , play with the settings then replace with a set of Works. but they have held up and functioned surprisingly well. I had figured on blowing them out well before now. When they do go I'll get the Works.
The lower stock shock mounts were removed with stronger mounts set lower into the a-arm. The upper mount is moved up and out.The upper and lower shock mount points are equal distance from the lower a-arm pivot point. With this mounting position the shock angle does not change as the suspension compresses. This enables full use of the shock stroke without any added stress on the mounting points or the shock

[Pripyat]

There are so many pages with broken links I was originally hoping for my project thread to include most of the information for the basic spiderbox fixes. I have taken lots of pictures so this post is to catch you guys up on everything I've done so far.

Heims install:
Tabs rough cut with a cut-off disk:


Cleaned up with a flap disk to prep for drilling:


The heims were purchased offline with the auction title "Economy 1/2 x 1/2-20 Panhard Bar Kit (1/2-3/8 HMS) .065 Bung Heim Joint". Actual OD of the inserted portion calipered out to .861".


I borrowed a 7/8" drill bit from a friend. I bolted my vise and drill press down to the table for the drilling operation:




Cut most of the lower portion of the bungs so that the thicker portion of the bung would be the contact point with the weld.

[Pripyat]

Swingarm before:


Swingarm After:


Here is the floor pan before I cleaned up the rust:


And After:


With first coat of paint:


I noticed the welds (or lack thereof) on the buggy left a bit to be desired.











I got the new 39t sprocket on and trimmed the chain to fit. I still need to remove the engine mount that interferes with the chain. Can I grind it off flush?

[tkeagle]

I don't grind it flush. Just enough to clear the chain. Maybe half way into it, on left side. Kind of angle it. I don't know exactly. Maybe 1/4 to 1/2 clearance. Would need to check. But don't need to grind it all the way out. I've never had any issues leaving much as can. Never know if might need another mount location for something.

[Pripyat]

One other thing - I don't think you guys understood what I was asking about the tie rod end threads. What is the thread of the tie rod end, boxed in this photo?



[edit] I'm an idiot, ckau already answered this. I misread and thought he had upgraded his tie rod.

To clarify, the thread in the red box is 7/16-20 RH thread?

[2nd edit]
How do you go from 7/16-20 thread to 3/8 with a high misalignment spacer? I can only find 7/16-20 rod ends with 7/16" hole. I can't find a 7/16" high misalignment spacer to drop me down to 3/8".
I can get 1/2" to 3/8" HMS but I can't find a 7/16-20 thread rod end with a 1/2" hole.

Or are you using a 7/16-20 rod end with 3/8" hole with cone spacers?

[ckau]

I did upgrade the tie rod. 1/2" tubing with a 7/16 ID to accept a 3/8 bung and heim. tube length is critical so measure carefully. they will be longer if memory serves, it's been several years since I did this. The conversion has work perfectly. Alignment has stayed spot on,steering is precise though the R&P box is starting a feel a bit loose from normal wear.

[xlint89]

You're beginning to see why i suggested you reinforce the front end now.

Unfortunately I failed to mention the swing arm. Only after you posted your pics, it jogged my memory.

Do yourself a favor and gusset the engine mounting bracket on the back. There's a lot of weight pulling down on that thing and it tends to bend causing issues.

I'd also look into getting a heavier duty engine mount/chain adjuster. The stock ones do fail normally at the worst possible time.

[Pripyat]

I won't have access to the kart for a couple days or I would have just gone and measured the ID and pitch of the existing tie rod. To reiterate, the existing (stock) tie rod is not 7/16-20. Or is it?

This kart project is getting alot more in depth than I was originally expecting. But I'm enjoying it. My son is 4 now so if I do everything right it will definitely pay off down the road.

[edit]
Ckau - I may have found the source of my confusion -

You said you have 1/2" tubing with 7/16" ID. Did you mean 3/4" tubing? I don't see any way to get a 3/8" bung on 1/2" tubing unless you butt-welded it.

[tkeagle]

Yes, the yerfdog are a project. But I greatly enjoy working on it. With the exception of $%^&@ brakes. .
Gives me something to work. And in long run, fairly cheap compared to other outlets.
The dogs, are one of the lightest buggy out there. They are fun for even adults. However, easy to roll over.
Seems like there is endless modes that can be done.

[Pripyat]

I finally got access to the buggy.

I'm trying to keep up with how much weight I'm adding to the buggy. Not much here..




This was taken just before I went absolutely nuts with the new-to-me MIG welder..


I added weld everywhere without thought. I just wanted the practice and figured it wouldn't hurt anything.




I was wrong. I put a bead of weld right by the holes for the control arms. I had to go back and grind it down.. lol

Also added weld where there wasn't any on the bulkhead mount. Haven't added a gusset yet. That is coming..


My son asked if he could help with final assembly. I may have startled him when I said, "YES!"


Hardware:
4x 1/2-13x8" for the control arms due the added plates.
2x 5/16-18x2" for the bolts that pass through the frame tube and into the control arm.
4x 3/8-16x1" for the bolts that pass through the bulkhead into the lower frame mount tab.

I still have the 2" spacers on the rear. The front looks pretty wide. Probably a good thing as it sits higher than I was expecting.





Fronts shocks are RFY. Going to try my luck with them. Actually looking forward to changing the oil in them and potentially doing a complete overhaul in the future. The catastrophic failures I've read about seem to be with the clevis mount models. As they sit they bottom out pretty easily by jumping on the front end (150lbs). I'll address geometry issues later. Ready to get this thing going.

[xlint89]

Looking good. The wider stance is a good thing.

The Yerfs are notorious for tipping over. Keep that in mind.

[Pripyat]

OK so I've been looking at the steering and think I have a course of action - It really gripes me that the steering rack isn't centered. I have a plan to get the buggy going for now but as soon as I find someone to cut additional slots into the steering rack I want move it center and down slightly -



Centering the steering rack will require a bunch of additional slots to be cut to the left of the pinion as pictured. Does this make sense or is this a waste? If I was going to get slots cut anyway, and fabricating new tie rods anyway, what are two additional holes in the bulkhead? That is my thought, anyway.

[tim]

Hey pripyat
ran across an old post the other day where one of these senior guys tried this and had trouble with angles.I might b talking out of turn so I'm trying to find it again to get you more information about who it was.Another thing I wanted to tell you was i use that same carburetor and so far so good.The thing I've learned about these carburetors is to spend a little extra money on a good fuel filter.
Hope this helps
Tim

[Pripyat]

Thanks Tim. I've been worried that once I get it all back together I would be plagued with carb issues. The only angle issues I can think of would be from the steering wheel to the gearbox. That angle would definitely be more extreme.

So I'm awaiting feedback on moving the steering box. I've got one more open item before I start welding tie rods. I planned on visiting this after I had played with the kart for a while but it would be easy to do now - I've read some on Ackerman and I haven't pulled any strings but it looks like the buggy could use some more.

I base that assumption on the fact that it looks like a lines drawn through the tie rod mounting hole through the pivot point of the spindle would not intersect at the center of the rear driveshaft. Not even close..

[tkeagle]

When I had my front end apart, I was looking at that also. Guess just didn't think was big issues if steering was offset or not. And didn't bother with it. I did reinforce the tabs that it was welded to. That area is easy to dismiss, cause it's not easy to see when all together. Last time buggy was flipped, couldn't understand why steering was so off. After taking apart, the tab did bend. And was almost snap loss. Good thing I checked it out, or could have broke loss, while driving. So if you do happen to roll, make sure you double check that area out. All that pressure goes somewhere.
You plan on putting fenders on it?
Looks good btw.

[ckau]

you won't gain from shifting the R&P. The shaft is longer on the passenger side to position the tie rod pivot points correctly while the box is mounted in the stock position. You will have to shorten the passenger side end of the shaft to match the drivers side otherwise you pivot points will be off.
The first pic shows a R&P with the shaft centered in the box . The box is centered on the mount. you can see the stock mounting hole to the left. you can see the different end lengths
the second pic shows the box with the shaft cut equal on both sides. The old stock tie rod end was reattached to measure for the pivot point.
The third pic is the finished R&P. The clevis ends were made with the correct length to place the pivot point in correct location in relation to a-arm pivot points This box also has 4 extra teeth cut into each side of the shaft to give longer shaft travel for a tighter turning radius.
Moving the box to center was done because it's in a single seat yerf. For a stock frame I wouldn't go through the trouble.

[x-bird]

Also looking at ckau's picture, you'll see he added a plate under the rack. This helps prevent "rotational" movement, stabilizes the rack and prevents bolt hole wear. well worth the little bit of time it takes to add in. just remember to keep your weld bead on the underside of the plate so it doesn't interfere with the rack or you'll be doing some grinding.

[BuggyMaster]

Wow nice job on this machine!

Seems that photobucket is charging people for image hosting or something. That may be contributing to the old links. The files just aren’t there anymore.

Keep up the good work!

[Pripyat]

I understand what you guys are saying about the R&P. My thoughts originally was that if I put, say, 8 notches to one side then I could shift the R&P over the distance of 4 notches with no consequence other than having additional steering.

Anyway, I wanted to get the buggy at least mobile this weekend. I had ordered some tie rod stuff that didn't work out..



Even with 1-7/8" of spacer the angle of the rod end (with cone spacers) wasn't even close.



The original ball joint offered a lot more rotation and it wound up (just barely) being enough. The rod I had already cut I ended up using to just extend the existing tie rods.



I don't have tall spacers to level the tie rods with the control arms but I'm rolling and this is just temporary. I'm not sure what I'll do in the end. The clevis route seems extreme to me since the existing point at the rack end seems stout.

Put the new brakes on but the threaded rod was too long. I was maxed out on adjustment and it was still engaging the cylinder. Had to trim a little off. Brakes are still very soft but are functional. I've bled them twice and am getting no bubbles out. But, the fluid hose does move a good bit when brakes are pressed. Maybe just needs to be replaced or upgraded.



Drained the gear oil. Looked.. milky.



I try to start the machine and I have a no spark condition. One of the spade connectors wasn't making connection so I cut the connector and used regular spade terminals.



I started to attach the seatbelts at the seat connection but I couldn't make myself do it. It just seemed wrong to attach a $300 harness on the same bolt that holds the seat down. Also I didn't see a way to attach at the seat mount screws that wouldn't have the strap rubbing on metal. Plus I'm learning to weld and need practice..





Those bolts are temporary. The plate is 1/4" welded all the way around so it should be plenty for a 150cc buggy.

I thought the exhaust leak was blowing the hot air right behind the center of the seats so I revisited my temporary fix. Drilled the hole out and tapped to 3/8". Had to modify my tap to get threads down to the bottom. Also had to drill the mounting hole on exhaust to accept the 3/8" bolt.





I later realized the hot air was coming off the engine fan.. LOL
I took the advice from the forum to just angle that engine mount that was interfering with the chain.



At this point I'm rolling around the yard slowly and everyone is freaking out wanting to drive it. We put about 30 minutes on it this weekend, never exceeding 20 or 25mph. Going to go through and tighten all the hardware before the next outing.

Next is electrical and lights. (unless advised otherwise).

[tim]

Great job.Buggy looks great

[tkeagle]

Looking sweet btw. How the front shocks working out?

As far as brakes. They pretty head racking. BD got a bench bleed method, that works pretty good. But I will still Half to go in and do some final bleeding, the old fashion way. But guessing not doing method 100% correct.
Had problems with my brakes all year. Finally after torn piston seal, replaced master and banjos. And replaced brake line. I'd say I got 75 to 80% brakes. But that could be debatable. Right now brakes won't lock up on dirt. But it's right on edge of doing so. So guess full anti lock mode now.
I know, can get them to do full lock up. But, feel much better with them now. I'll let kids take out, at this point.
Haven't done this yet. When doing bleeding, have someone slap the line around. Help get any stuck air pockets out. Seems to help.
Far as lighting, sounds good. But be confident that no under line issues are present in electric system now. Or will be chasing your tail. And do one mod at a time, what ever that might be. Don't recall what you got for stator. But if plan on any type led bar. Suggest having a 11 pole stator system.

[Pripyat]

I appreciate the compliments. The wife/kid see new red paint and don't appreciate all the underlying labor.

I mocked up some schematics earlier this evening. Plan is to put the lights on the battery circuit with an on/off switch. I knew using the existing light wiring (off the regulator) with an LED would be a bad idea.

Is 38 watts too much or am I going to have to upgrade the stator? I assumed the stock lights were at least that.

The front shocks are awesome at 10mph. I put 100psi air in them as there was hardly any pressure at all. They max out very easily. I plan to work on them in the next couple weeks. I can get 120psi out my compressor. I believe this will be OK for transportation but they need help for anything more than that.

In 30mins this link should go live with a video of some low speed riding on stock rfy's except for pressure increase to 100psi. Tons of travel considering we are barely rolling.
https://youtu.be/r8TYPbqyXd8

[x-bird]

http://www.ebay.com/itm/FOX-FACTORY-...sAAOSwdYlZozGb

[Pripyat]

Is increased pressure all the RFYs need? I've read a good bit about the RFYs and apparently changing the oil (or at least filling them with the proper amount) makes a big difference. I'll do that once I figure out what weight oil to put in.

Also - My #1 complaint with the kart at this point is that once you get going (about twice as fast as the video) the floor pan pops in and out and makes one heck of a racket. If you put your hand on top (where your foot lies) and on the bottom of the floor pan (just above the ground) you can pop the floor up/down. I can't think of any way to stop this.. Also at 3/4 speed the engine gets very loud. Not sure if it is the exhaust or other. I'd prefer it to be as quiet (unnoticed) as possible.

There was a comment about mug guards. I'd love to have some but I'm not sure if they are worth the weight. They would definitely be nice, though. Wife slung mud in my beer the other day.

As far as the steering rack goes I keep thinking of ways I can make a jig or guide to cut the additional slots myself. Has anyone here tackled that themselves? How did you do it and how did it work out long-term?

[edit] Also - While I'm thinking about it - There is a thread on here where a guy drilled and tapped two holes on the RFY shocks so he could fill from one and bleed from the other. Can't this be done with one hole and some patience?

[tkeagle]

As far as mud flaps go, or fenders. BD makes a set, front and back. They aluminum. Very light weight. Don't believe they will lose any power as far as weight goes. Well worth the $$ and VERY affective, if installed correctly.

Floor pan?? maybe kill 2 birds with one stone. Cut out the old one. Put aluminum back. Cant weld it, to frame, but can cut to size, predrill for sheet metal screws, or make tabs for it to connect to. I'm guessing, you'd get rid of a lot of weight. A project I still plan on doing this year. Once get other things taken care of.
HINT::: pretty much all traffic street signs are make of a good quality Aluminum sheeting. Always need to replace them, due to reflective sheeting requirements. Cheaper to by new, then have someone replace the high price reflective sheeting.
Guessing a Local city, county or State maintenance office might have some out dated signs in there shop, can give away, or buy real cheap. They just take up space.
I know this, because I work for Kansas Dept. of Trans.
Might half to sand and polish up the sign. Back of the sign facing up. The reflective sheeting on bottom side, will just help protect it.
If done right, thinking would look pretty sweet. Very affective and will lose a good amount of weight.
I know those signs don't look all that big going 70mph down the road. one mid size sign, would be big enough to cover for floor pan.

[x-bird]

floor pan is "oil canning" in old school terms. It may have taken a hit that stretched the metal or the frame is a bit twisted. quick fix would be to cut slot across the area it's popping at in the shape of a "T" or "x" and weld it shut.

[Pripyat]

"Oil Canning" I love it.

I pulled one of the RFYs off to play with it and I can't get over how loose everything on the buggy is. Both front wheels had 1/8" of of play where the axle nut needed to be tightened. Is there supposed to be a spacer between the bearings? I'm using the BD heavy duty hubs. I'm assuming they weren't pressed in fully when I put them on.

The bulkhead was loose at the upper frame tube connection as well. I'm tempted to drill the holes out and weld in inserts at that connection. I believe I saw that ckau had done this. The bulkhead connection was slightly tweaked when I assembled everything. The upper bolts were off to one side, not centered in the slots cut in the bulkhead. Should I plan to try and correct this? I'm assuming this is why one of my extended tie rods measured out to be .25" longer than the other.

Lights are here but not properly mounted. Lots of updates in the next week or two..

[tkeagle]

I'm always checking the bolts in the front end. Just habit. Sometimes those bulk head bolts will work lose. Not sure how tight yours are. But where the a arms connect to bulk head. I need to tap them in with hammer. They that tight. If you got gaps in there. Might need to throw in some correct size washers. In return might help the overall stability of front end.
My bulk head isn't perfect either. The right side is slightly higher. Noticed this last time it was rolled when took front end off. Was alot worse. Extended the 4 bolts holes that connected the bulkhead to frame. Give me a little more adjustment. Went back on pics of buggy years back, and if look at it. Been that way for awhile. Just really never noticed.
So not sure how big issue it is. Something might work on later in year. Runs fine as is. But think explains why left side tie rod is extended out may half in more then right, to center the wheels. ????????
I use 1inch spacers on front tires.

[Pripyat]

So I messed with one of the shocks a little bit. The aluminum they are made of is very soft. I scuffed the shock all up trying to figure out how to disassemble the thing. I'll post more pictures and how-to when I get to the second shock. I made it a lot more labor-intensive than it had to be...



A tool is required to get the threaded piece off the bottom where the shaft goes into the shock body.



The tool worked but for the life of me I couldn't get the seal out the bottom of the shock. I used every means I could think of (minus a slide hammer) and it wouldn't budge. Ended up not pulling that part of the shock apart.



I didn't use the bottom hole at all so on the next shock I'll only be drilling/tapping a single hole. I passed a LOT of fluid through the shock trying to get any trash out the shock body since I wasn't disassembling. Filled with 7wt and re-assembled.



I still don't have all the air out but it feels entirely different. Like a different shock. Perceived stiffness of the shock is night and day. The feel didn't really change until I got to the last little bit of air. Apparently air bubbles are a big deal. More on shocks later.

I cut up the mounts for my light bar and prepped them for welding.







I was about to zip tie a motorcycle tail light onto the buggy then remembered I had the welder. I only had a piece of scrap steel from a filing cabinet so I made do with what I had..

Looks really shotty but I'm actually quite proud considering it only took an hour.

[Pripyat]

I took the buggy to some land (TONS of sand and hills) and had loads of fun on the buggy. No issues whatsoever.



There are a couple open items.

1) The slop in the control arms between the control arm bushings and the bulkhead. There is at least 1/16" gap on each of the four. I'm assuming nylon washers would work great but I don't know the OD of the steel rod (or ID of the bushings) without pulling the front end apart. Anyone got washer dimensions or recommendations?

2) Need to finalize wiring. There is a voltage wire going to the regulator 100% of the time. Color is Y/R. During some testing I removed the battery from this wire while the engine was running and I heard a clicking coming from the engine area. Arcing? What was I hearing and what is the consequence of this happening? I did weld in a new tab for the key switch.



3) When I trailer the buggy it won't restart when I get to my final destination.
A) The bouncing on the trailer is making the carb float flood the engine. I'm fairly certain it actually got into the crank as the oil after the remote ride was runny. I put a (home plumbing) valve on but this only helped a little as I put it upstream of the filter. I'm considering putting vacuum petcock just before the carb.



B) The battery is weak. I put a new larger-than-stock battery in the buggy but it is sitting at a fairly extreme angle. It will turn the buggy over maybe 5 rotations before it just dies. Not sure if it is just a bad battery or other.

4) Power.. I am yet to play with the jetting (I have a main jet assortment). This thing needs about twice the HP it currently has. It won't spin the wheels in loose sand from dead stop. Has a fairly slow top end. If I do an engine swap it has to have sequential gears. Can you guys make a couple suggestions for me to do some research on? A 3 speed with a clutch would be really cool.. I doubt I'd go through the trouble to do a swap unless it added manual gear selection (with reverse a big plus).

LOL I need some type of brush guard or windshield.


The big mantis (shoulder strap on the left of pic) rode for at least 30 minutes.



It is tons of fun, though. The kids (15yr old girls) love it. My 4yr old likes cruising around, too.

[Pripyat]

Since no one is biting..

I tried a 125 main jet in the buggy. I had read this was a good starting point with a UNI filter. The jet that came with the carb looks more like a 105. Seems like the 125 helped with acceleration and top end but I'm getting a lot of popping on decel. Not to mention after the run the buggy completely died (seemed like it quit firing, possibly fouled plug).

So I'll likely go just a size larger than stock and go from there.

My top speed is around 26mph. Stock engine except for UNI filter. 22's on rear, 39T sprocket. Does that sound right? Seems awfully slow. I ordered some 12g sliders and 1.5k springs to drop in as a tuning starting point. Before I look too much into engine swaps...

[JERSEYDEVIL]

yes w/ a 39t that sounds like a ballpark top speed from my experience swapping sprockets on a yerf.

[tkeagle]

Think mine are 22's, and have 39t sprocket. with 200lbs I don't have issue going 30mph. But that's about max, unless going down hill. Son can get 33mph I think. I think with some more tuning, you should be able to hit close to that. Do have upgraded clutch from BD. But not sure that will change top speed that much.
Might think about go 175cc route. One I got from BD, was very nice improvement. Can peel out, on the hardest of dirt. With slight incline, can even get front tires to lift a little.
It's a true plug and play. Save you a lot of head aches. Can buy the full engine from them, or they got everything you can buy from them, and you upgrade your self. save about $300 that way, if I recall correctly.
Even thou very cool idea to have much bigger engine, with a trani with gears. Think you'd half to do alot more reinforcement to entire buggy. Remember, yerfs are gokart. Why they so light. My yerf has been rolled 3 times. All under 20mph. Thou with stood the rolls. Something did give out. And always needed repair. Roll one say at 40 or 50mph. I'm not sure how that would end. But know my kids wouldn't be getting in it alone. . Still I'd like to put in a fl Honda 350 2 stroke in a yerf. Just see what it would do. But no longer a kids ride.

[Pripyat]

You guys did not tell me these things multiply!



Is there a contest for worst condition buggy? If there is I think I have a candidate. I posted a wanted ad for a go kart that didn't run. This guy messaged me and said I could have it for $50. The engine was recently rebuilt and it needed a steering wheel. I drove 2 hours to pick this thing up..

Not sure how this even happens. Not to mention hub is welded on axle.


Engine mount tab apparently broke at some point. Welds all the way around.


JB weld?


Lower bulkhead mounting tab had apparently broken off at some point.


The frame attachment above the bulkhead appears to have been re-welded, too.


Lower tab has been replaced. Ball joint replaced with hex bolt and lots of washers. Gussets on spindle cut off to accommodate large washers?


Opposite side they used a carriage bolt.


Has uneven control arms. Upper is bent pretty bad along with the tie rod.


I have no idea what I am even looking at here..


Has a neat gas tank. The guy said that "there was some trash in it".


View inside the tank:


The thing had no brake caliper. I'm assuming this nut/bolt is cross-threaded.


There was no air box or air filter. I asked where it was and the guy said that there wasn't one when he got the buggy and his kids ran it without one. Engine was using a quart of oil per hour so he honed the cylinders and installed new rings. Engine makes compression but he couldn't get it to fire due to some electrical issue. Didn't have time to work on it so he sold it.



I just wanted it for spare parts although I think the only usable items are the steering box, frame, and seats. There is 20 or 30 degrees of slop PER WHEEL due to the lack of ball joints. This dude had his kids driving this thing around..

[Pripyat]

So I'm getting really annoyed by constantly having to have the buggy on a charger to get it started. As i described earlier I could only get about 3 revolutions out the battery before it was too weak to crank the engine.

I remembered the previous owner telling me that he had replaced the starter. I swapped the starter off the trash kart I just bought and it works much better. I believe the gearing is different or something.. the one from the trash buggy spins the engine much slower but longer. The one I've been using spun the engine quicker but when the battery was weak it wouldn't do anything at all.

I should mention that the starter off the trash buggy has its terminal JB welded in place.

[xlint89]

Make sure you have a really solid ground. Alot of times the engine to frame ground is in bad shape and causes issues.

Also not a bad idea to increase the wire size for some extra ooomph....

Lastly, what kind of battery are you using? Don't cheap out there.

I use a maintenance free battery with little issue. About $75

[Pripyat]

I'm usually pretty good about batteries but I did skimp slightly. The battery is a standard motorcycle battery (lead acid variety) but I did go up a size to a 12N9-4B-1. Had to bend my battery tab to get it in there. Maybe I should have gone with a gel or AGM. It does sit at a pretty extreme angle on the lifted swingarm. If you will recommend me a battery that will, 100%, never give me a problem I'll likely just go ahead and get it. I despise being stranded.

I'm also looking at stator/regulator upgrades but would rather piece something together than buy a kit. I'm not willing to pay $110 for everything pieced together but will spend $200 trying something myself that may not work.

Also - During testing yesterday I added an extra ground directly to the starter (mine was missing) so that isn't the issue..

[Pripyat]

Son already has 1 gas 50cc dirtbike, 1 electric dirtbike, 1 electric atv, and 1 electric dune buggy. He's going to be 5 soon so he definitely needs a buggy..

Picked this guy up used today:




My thought is that I can fix some of the obvious stuff and still have less in the unit than a new one would cost. It's only a few years old. The guy bought it and immediately had issues with the chinese engine. From what I've read they are really terrible. He had someone put this 212cc predator on the kart but the clutch overheats in just a short amount of time. He didn't care to mess with it -



I'm assuming I'll be putting a torque converter on it. The wife will be paying for this so what is the best, most cadillac solution to the drivetrain?

[xlint89]

My battery is an AGM. Can't think of the name right now, but any good name should suffice.

Ran a TAV on my nephew's Yerf with that Predator engine. A bit bigger and weighs more, it runs about 33 MPH. It should pull that one you bought quite well.

[BEEFKING69]

20 Dollar lawnmower battery from walmart is what i use on all of my buggys.....I refuse to pay 50+ dollars for some garbage bullcrap motorcycle battery just because its compact.

[Pripyat]

I had planned on fixing up the predator on the mini kart but will likely source something with reverse, electric start , and a charging system.

Any suggestions?

[BEEFKING69]

I would just keep the 150 and add a reverse box.....Edit which buggy you talking about?

[Pripyat]

Sorry - maybe I should start another thread.

The mini kart has a 212cc predator with the clutch overheating. Mini kart also has an unused key ignition, headlights, taillights, horn, etc that my son would love.

I've decided to pull the predator off and replace it with something that has reverse and a charging system. A chinese ATV 125cc 3spd auto with reverse is about $250. Looks like this may be the way to go unless someone steers me elsewhere.

[neo71665]

Once you drive a buggy with reverse it's hard to go back to a go kart with a lawn mower engine

[Pripyat]

Yeah I have no idea what I'm going to do with the predator engine.. I've seen spiderbox predator swaps but the cvt and the charging system is a lot to lose..

[BEEFKING69]

Sell the predator.

[Pripyat]

I made another thread for the kandi mini kart engine swap to keep things simple.

The trashed spiderbox I bought had been run with no air filter. The guy I bought it from said he had just re-ringed and honed the engine but hadn't run it yet. I was curious and pulled the oil screen. This is what I filtered out the oil:



Wtf? So at minimum the guy put the old oil back after he honed. Or didnt drain at all? There were whole ants in the crank..

I wanted to fix up one engine (cam, valve springs, polished intake) while the other was in the buggy but I'm thinking my best option would be to throw this engine in the trash. Or maybe try and get it running and it can be the temporary engine while I invest time in my original engine..

[fan4chevy]

Amazing restoration.

[tim]

Wow! It is amazing a man will look you in the eye and lie about replacing rings for $50 .I would not throw out that engine i would use it to tear down and teach myself everything I could about gy6 engines.Although looking at your buggy you are miles ahead of me in mechanical skills.I think your buggy looks great and the detailed picture upgrades helped a lot of us

[Pripyat]

Thanks for the compliments - I'm still working through the open items I listed a couple posts ago. Almost done with the wiring and shimming the control arms.

I have no idea what is going on with the trash gy6 engine. I don't know what to believe any more. I'm considering flushing the crank with diesel fuel, putting fresh oil in it, and seeing if it will run.. If it will then I may just throw it on the buggy while I go through the known good engine.

[neo71665]

I 2nd not trashing it. Heck I've brought back chevy v8s where we had to beat the pistons out with a BFH because they were rusted in place. That engine ended up doing 9.16 second 1/4 mile passes.


Looks like the guy pulled the head off it, let it sit for a long time, and just threw it back together with some rings. I bet if you tore it down and cleaned it real good it would be fine.

[xlint89]

Cranks and cylinders aren't anything special.

Keep the cases and head at the very least.

Port and polish the head plus port match the intake and exhaust manifolds yourself to get some free HP gains on the head.

The cases can be bored out for a big bore cylinder kit.

Stroker cranks can be bought too

Keep the known good engine in the buggy, while you build the beater engine.

[Pripyat]

My grandfather-in-law started a tractor business in the early 70's and has been working on engines ever since. I asked him about the engine that had been run with no intake. He said the valves and stem seals would likely be excessively worn from all the debris. Not really a big deal but definitely a lot more work than I want to volunteer for.

Someone said thanks for the detailed pictures - I had quit posting progress pics but here are some from last night -

There was some slop in the control arms. The rod they rotate on is longer than the control arm and I had some concern about dirt/sand/grit making its way into this gap. I thought there was a lot more gap than there actually was..





The OD of the rod is between 5/8 and 3/4 so I reamed out some 5/8 arbor shims to slip over the rod. I stacked two to make up most of the difference in length.



I have only done one control arm but it helped a lot. There is still some movement but it is due to worn bushings or worn rod.

The stock tie rod end on the spiderbox has a M10x1.25 thread pattern that passes through the spindle. You can get wheel spacers off ebay (qty 8) for less than $20 with that same thread. Threads right onto the ball joint and has male thread to go through the spindle. Uses the original nut.

When I installed the risers my tie rods were too long.

I liked the way my temporary ones turned out so I started on new, permanent ones last night. 3/4" BOM (bent over mandrel) tubing with .058" wall thickness slips over the stock tie rod perfectly. The fit is so tight that with just 3/4" inserted I feel confident that it is near perfectly straight.



More pics and details later.

Another note - It is possible when you are tightening your high-misalignment-spacers on your rod ends to bend them. If you are sitting at an extreme angle the spacers can ride on the stationary portion of the joint and get bent.

[Pripyat]

If I decide to build one of these engines I would have to get around twice the current power output to justify the time/cost. I'm reading this is quite possible. I have no reservation about having parts professionally machined where required.

What is the largest reliable setup? I've read a lot but some setups come with a replacement casing which negates the issue with 61mm and larger pistons? I don't see much at all about stroker setups. Not sure why.

[xlint89]

Tom at Syc Powersports has a large reliable engine. He'd be the one to ask.

I personally have had great results with my set up. Mine is listed in my sig at the bottom of my posts.

Not sure about being able to double the HP output, but you can definitely make large gains.

As I eluded to in previous posts, the factory mass produced engines are not high quality. They can be MUCH more potent with just some massaging and little $$. There are a lot of casting flaws that can be cleaned up that would allow more air to enter and exit the engine.

Couple that with some head work (porting), camshaft, an unrestrictive air intake and exhaust, and you've got a much more responsive engine. Plus you don't have a lot of $$ into it. If your top end is wore out, you can also consider bolting on a slightly larger 58.5mm cylinder (largest you can reliably go without boring the cases)


Of course you can go big, but you're going to start to get pricey too. You're now also looking to split the cases for a stroker crank, and or machine them for a larger cylinder.

This stuff ^^^ can all be added on later to the original build if planned properly.


Here's some reading info:

http://buggymasters.com/forum/showthread.php?t=4191



Here's a rough idea of what can be achieved:

Post #11

http://buggymasters.com/forum/showthread.php?t=2670

[Pripyat]

I've stumbled across those two threads many times over the past couple months..

There are some crazy cheap parts on ebay. I was thinking about ordering direct from china and seeing how well it holds up. Oversize jug/piston for 50ish, stroker crank for 100ish. Get them before Christmas, throw them in trash engine with a reworked head, filter, and exhaust.

Could be interesting.

[xlint89]

This is actually funny. You don't want Chinese parts.

Believe it or not, the "good" stuff comes from Taiwan.

Taida = good

NCY = not bad

But if you want quality valve springs. Contact Tom at Syc. He's got the hook up.

If you plan on revving the engine up, I strongly suggest getting them. Weak springs lead to float valve. Float valve leads to engine failure.

I've bent valves twice. Once I bought the good (American made) springs the problem stopped.

[xlint89]

If you've read my posts, than you can see that you can boost your performance with little $$ involved.

If you want to double your HP, that's a bunch of $$ invested.

I'd suggest doing the cheap upgrades first, then see if it's worth adding more on top of those

[Pripyat]

Well I honestly thought there would be more enthusiasm for ticking timebomb high output chinesium extreme budget build.

My thought on the Chinese parts: isn't that what is in there now?

As far as dollars invested if I get cheap inferior Chinese parts:
Engine machining: free
61 or 62mm piston: 50
3mm stroker crank: 100
New head/rebuild/port: 100
Exhaust: home-made or other

I figure the head will be the most expensive part since there is the most to gain there from what I'm reading.

Less than 300 invested doesnt seem like a lot to me if I can get a couple hundred hours out the engine.

[xlint89]

I would love to see you build a monster engine. I try to help guys out using the least amount of $$ possible.

If you're looking for HUGE HP gains, a built GY6 might be a let down. I think they make 9 HP stock. You're prob going to see 15 HP at the most with a maxed out engine build.

Might be worth looking into an engine swap at that point. ATV or sled engine would have much more RELIABLE HP available.

HOWEVER: with the built GY6 you have no fabrication needed to make the engine fit. You can easily install reverse onto it. It already has electric start. And no need to fabricate a cooling system.

Plus the Yerf is one of the lightest buggies produced. They didn't use heavy gauge steel. And as you up the HP, you're going to find that the frame and axle will need beefed up as well. Not to mention the brakes should be upgraded as speed increases too.

So, now you see why I'm not gung-ho on the monster build?

It's a yard cart that is fun. Can it be made reliable? Yes
Can it be made more durable? Yes
Can it be made more powerful? Yes

Is it worth it to you?


Addressing the Chinese parts. Yes, that's most likely what's in there already. Not the best quality controls. That's why there's so much performance gain available from just cleaning up casting flaws and port matching. The engines run reliably because they are not high strung and adding more stress on the parts like you're looking to do.

You really do get what you pay for with cheap parts on this stuff.

When boring the cases for a big bore cylinder the spigot gets really thin in spots. This is why Tom likes a steel sleeved cylinder to aid in support of this area. That's not going to be a $50 cylinder and piston I'm sure. I have been fortunate enough to not have issues with my NCY Nikasil plated 62mm cylinder and it was prob around $90 for it.

I can't comment on the crank, but mine was around $200. Ruima 2.2mm and it was way beefier than the stock connecting rod. I had pics of the comparison, but Photosuckit blocks the pics from coming through now.

The head i used was a Taida large valve $160 and then cleaned it up a little myself.

The TK exhaust I used was pretty expensive. I want to say almost $300 but is supposed to be one of the best. I had good results with the stock header and a FMF silencer before the build. Not sure how good that header would be once the engine size was increased.

I didn't see your carb listed. The stock 24mm would prob be holding you back. I like flat slides myself, and went with the Mikuni 28 and have had great results. Around $100 for it.

UNI air filter $20

A12 cam shaft $35

Plus the cylinder spacer for the stroker rod, longer timing chain, quality (USA made) valve springs, etc.....

You might be able to build an engine for under $300, but I seriously doubt you will get longevity out of it using cheap parts.

I bent the valves on my head once, and completely broke them and the piston another time. That was before I got the GOOD American made valve springs.

[Pripyat]

Thanks for all the feedback. Changing topics to swingarm engine mount reinforcement - does the chain tension mounting tab break off of the tubing or does the tubing split down the center? Recommendations on how to beef this up?

Pics for reference:

[ckau]

The constant pull and flex on the rear motor mount/chain adjuster will eventually crack the welds and fatigue the tubing. A piece of steel plate overlaying the stock mount and wrapped around the tubes will spread the load.

[xlint89]

I like Ckau's idea better. Mine was just 2 gussets on either side of the mount.

Like he said, the mount starts to sag. Another thing is the actual adjustable mount broke on mine. Installed a beefier one and haven't had an issue

[Pripyat]

OK can you explain how many pieces of steel I'm looking at?
One for the flat piece on top with the through-hole for the engine mount. Is it sitting on top of the existing mount? Second that wraps around the large top tubing. Won't there still be a height difference (assuming plate is sitting on existing mount)?

Then a third that spans the large top and smaller bottom tubing.

At what point do I need to add the bar you have across the bottom from left to right?

[ckau]

there's one piece of steel flat plate notched to fit around the stock motor mount bracket then formed to wrap around the top large tube and the smaller bottom tube. The plate spreads the load across a larger area rather than just at the stock mount weld points.
The bar across the bottom keeps the swing arm from spreading out during downwards forces. This bar does a lot for keeping the swing arm square and removing flex. the bar does however make motor removal and installations difficult. The motor has to be muscled through the side rather than dropping out the end This swing arm addresses just about every fail issue I've ever encountered. The bar running forward off that bottom side to side bar supports a center axle bearing. There are five axle bearings total, 2 on each axle end in the boxed sections and the fifth in the center. This swing arm uses a Azusa 1"x 42" keyed axel with custom wheel, brake. and sprocket hubs. The swing arm also sports duel rear brakes.

[x-bird]

same results, slightly different approach ... I've also always tried to put a 1/8-inch or so thick rubber washer on both sides of the mount plate to soak up a bit of the initial throttle hit. never had any chain tension problems with that little bit o cushioning added in. Not shown in the pictures here as this was still setup stage.

[tkeagle]

I took 1/4 inch angle iron. Placed it so was over the top. And the other side slid down back. Think angle iron was 1.5x1.5 width. Then welded all on brace and tubing. Was long enough so went past the engine brace by 2 inches.

[Pripyat]

What would be the consequence of placing a large valve 61mm head on a stock displacement engine?

[neo71665]

Not sure on a gy6 but if you shove too big of a valve in the head the valve opening is bigger than the piston opening. That can lead to the valve basically being clamped shut between the head and jug in this case. It's not common but I have seen it happen before and I'm not real experienced on these so it would be something I would look for.


Other than that make sure the piston isn't gonna slap the valve. That is pretty common on other engines when toying with the valve size and lift specs.

[Pripyat]

I was thinking of sourcing a larger cylinder head and throwing it on the stock engine while I mull over whether I really want to bore and stroke. But, if the larger headspace causes poorer performance with the stock cylinder/crank then obviously that wouldn't make sense. Hopefully someone will chime in and clear that up.

Anyway, I started pulling the trash engine apart. I am really confused by these studs. One only has 2 threads engagement, max. The other has excess? What happened here?

It looks like the guy stored this cylinder head cover under a tree.


One side of cylinder looks OK, other side has soot all over it. Definitely doesn't look honed unless the guy has no idea how to cross-hatch.




Piston scrubbing


Interestingly the piston is textbook for "damage from debris getting through air filter". This site that explains diagnosing type of piston failure is for 2-stroked but still an interesting read - http://www.madsens1.com/saw_piston_fail.htm

[x-bird]

two studs in first picture need swapped. surprised that held together, i doubt it has correct torque with so little thread engagement. looks almost like very dirty/debris contaminated oil ran thru it without a filter screen.

[Pripyat]

That makes perfect sense. I thought there was just carbon in the cylinder at first glance but after I cleaned it up I realized it is in pretty bad shape..

[neo71665]

Man the last guy that worked on that thing has no right to be in the same room as a set of tools. Matter of fact a pencil might be too advanced for him.

[xlint89]

A large valve head isn't going to really hurt performance on the stock engine. But if it's a larger bore cylinder head, you're going to have lower compression. Not good for bottom end.

There are 2 long and 2 short cylinder studs. Looks like the previous guy didn't want to take the cyl back down to reinstall them correctly. Lazy.....

[Pripyat]

Did I mention that the exhaust was only held on by a ball of weld? The other stud is broken off in the head. I had to grind the weld ball off to get the muffler off.



Head had been recently cleaned up..





Cleaned it up a little -



Bottom end is up next..

[edit]
This may help someone in the future - Someone please correct me if I'm wrong - I read around and found a thread about a guy who put a stock cylinder head on a 61mm cylinder. The compression was increased and he ultimately had to go with a 61mm cylinder head to get the compression back to around stock levels. Continuing with what xlint said before, doing the opposite (61mm head on stock cylinder) will lower your compression due to the extra cylinder volume in the head.

[Pripyat]

Took the buggy to some land and did some sweet jumps.

https://youtu.be/4uiRmKHFSkE

It was loads of fun until..







I'm debating going away from 5/8" axles. Would really like tapered trailer type. Need to do some research..

[Pripyat]

Took the buggy to some land and did some sweet jumps.

https://youtu.be/4uiRmKHFSkE

It was loads of fun until..







I'm debating going away from 5/8" axles. Would really like tapered trailer type. Need to do some research..

[BuggyMaster]

Dangggggg!!!!