Product Link for 9t Sprocket for Yerf 3202

[Old_Dog]

My 9 year old son is pretty stoked on his 3203 Yerfdog... until he hits the hills, and our property is pretty much all hills. I plan to adjust the torque converter spring to the #3 position to get it to shift later. Additionally, I would like to change the driver sprocket from the stock 10t to a 9t to get a bit more climbing torque. Can someone who has done this before please send a link to the exact part?

I found some 9t sprockets here: http://www.*****************/sprocket.htm but i see one with a keyway and one with a built-in key. I know I could disassemble to see which one I need, but I have limited time. So, it would be a big help if someone could tell me which it is I need so I already have the part before I take it apart. Also, if you have a better parts source than the one I posted, please pass it on.

Finally, how do I keep the driver pully from spinning while I loosen the bolt?

[x-bird]

To remove the bolt you can use an impact gun/drill or remove the engine cover and hold the flywheel with a screwdriver between the fins. another trick that would probably work is to use a plumbing rubber strap wrench to hold the outer.

[Old_Dog]

I thought about jamming something in the flywheel fins, but I was afraid to crack one. I'll go ahead and try it and hold you responsible if I bust it

Thanks for the tips!

[x-bird]

be gentle grasshoppa! use a piece of 3/4 or 1/2 inch thick piece of wood if you want to be on the safe side. if you do break one, you can always knock out the remaining every other fin ...somewhat common mod to cut rotating weight, ;~) . impact or strap wrench are the two "safest" ways to go about it.

[speedshopmike]

if you dont have an impact the strap wrench works great as X noted.
if you dont have a strap wrench use the belt itself with a prybar wrapped in it for leverage.
dont use a flywheel fin.

the stock sprocket is self-keyed.
you can go either way but self keyed is easier to deal with.
be careful what you buy; the stock yerf sprocket is very narrow; mine's out and i can measure the hub if you like.
the 8 tooth i changed to on mine needed the sprocket hubs narrowed to fit.
ps: stock yerfs are spec'd, to my knowledge, at 10 teeth.
mine had a 9 tooth in it; i dont know if it was stock or not but you should count yours before ordering so you dont make the same mistake i did and waste $ buying what ya already had.
that said, i have a brand new 9 for sale if you dont mind grinding the hubs down to fit.

[Old_Dog]

I found a really easy way to hold the driver still. I used a long bar clamp. The rubber jaws won't mar the metal. The 3' bar sticks out against the frame and keeps it from turning. The clamp doesn't need to be very tight to get a good grip.

[speedshopmike]

dont go too tight; distorting the outer housing will give you engagement chatter.
clean and lube your chain

[Old_Dog]

Originally Posted by speedshopmike

clean and lube your chain

ha ha! you should have seen the cart when we got it. the carb looked like it was dunked in pig poop! have you ever seen pig poop? we'll get to the chain right after fixing the brakes, replacing the throttle cable, cleaning and lubing the torque converter, swapping out the driver sprocket, adding some extensions so my son can reach the pedals, adding headlights, tailights and a safety flag... unfortunately, I can't work on any of that until I finish running electric wire around the goat pen and remodeling the chicken coop

[x-bird]

Originally Posted by Old_Dog

adding some extensions so my son can reach the pedals,

somewhere around page two of "my yerf upgrade thread" I have some pictures of the set of pedals i made for my daughter. 2 bolts and 2 nuts to install or remove them. As far as flags go, I intend to install them once i've finished building my daughter's cart, i have some old golf flagsticks and flags--much stiffer fiberglass, i'm going to hose clamp them to a vertical frame bar. you can probably get some free if you have a golf course or driving range near you. i've got piles of them, the sticks get snapped off from the ferrules by the pickers and mowers quite often.

[speedshopmike]

roger that, old dog, i understand.
i dont spend much time with pig poop, but we have a cow named daisy next door and one of my dogs really enjoys coming home covered in dripping green cowpies.

[xlint89]

Another option for the hills is the stiffer "yellow" spring on the TAV. BMI sells them for around $15.

http://www.*************/item/Comet-Y...g--216168-7713


Sprocket

http://www.*************/item/TAV-Rep...or-400835-2258

[yerfdogman]

I had to move my pedals on the yerf dog up about a foot for my kid to reach them. I cut the existing rod in half and threaded the end of it. I got 4' of 5/16 rod, (2) 5/16 couplings from the hardware store. I cut and thread to length. I used the coupling to combine the original rod (which I cut in half) to the new rod. I used a nut on each side of the coupling as a jam nut. I had to notch the gas pedal where the rod goes through. I drilled a hole through the tubing to mount each pedal at the new location. I made 2 short rods and 2 stock rods so I can drive or my kid can. I used the coupling so it is easy to take off without messing with any other linkages. Cost less than $10. The yerf dog rod is less than 5/16 diameter, maybe 1/4" but i used 5/16".

I got the 8 tooth sprocket coming soon so I can hopefully climb hills.
I cut the front 5" (2 front holes for motor) off of the existing comet jack plate. I then notched out the middle 2 holes on the jack plate (for the motor). Now I can slide the motor forward away from the tc and tighten the belt as needed. Use both side of the plate so it maintains the same height.

[Old_Dog]

Progress Report:
Before I took my jackshaft apart, I looked at the end and it appeared to me that the shaft had an open keyway, so I ordered the sprocket with a built-in key. However, after I removed the driven pulley, I discovered that the keyway actually has a long piece of key stock that runs ALMOST the full length of the shaft. It didn't reach the end of the shaft that stuck out, so it appeared to me that the driven pulley and the spocket must have built-in keys. So, I'll have to exchange the sprocket with the built-in key for one with an open keyway.

This seems to be the correct part:
http://www.*****************/jackshft.htm
Part Number: 202154G
SPROCKET 9 TOOTH W/KEYWAY for #40,41,420 CHAIN

I had a hard time removing the old sprocket. The keystock that was present in the jackshaft was warped just in front of the sprocket. I hoped that I could force the sporcket past this bulge. I placed a rod behind it and started tapping, turning, tapping... I thought I was making progress as I got the sprocket to move a few inches. Then, I realized that the keystock was sliding out of the shaft along with the spocket. So, the keystock was sliding out of the shaft along with the sprocket. I'll also need to buy a piece of 3/16" key stock the full length of the shaft since the old one is warped.

I'm wondering how difficult it will be to slide that new keystock into the keyway in the shaft.

[Old_Dog]

Originally Posted by yerfdogman

I had to move my pedals on the yerf dog up about a foot for my kid to reach them. I cut the existing rod in half and threaded the end of it. I got 4' of 5/16 rod, (2) 5/16 couplings from the hardware store. I cut and thread to length. I used the coupling to combine the original rod (which I cut in half) to the new rod. I used a nut on each side of the coupling as a jam nut. I had to notch the gas pedal where the rod goes through. I drilled a hole through the tubing to mount each pedal at the new location. I made 2 short rods and 2 stock rods so I can drive or my kid can. I used the coupling so it is easy to take off without messing with any other linkages. Cost less than $10. The yerf dog rod is less than 5/16 diameter, maybe 1/4" but i used 5/16".

I got the 8 tooth sprocket coming soon so I can hopefully climb hills.
I cut the front 5" (2 front holes for motor) off of the existing comet jack plate. I then notched out the middle 2 holes on the jack plate (for the motor). Now I can slide the motor forward away from the tc and tighten the belt as needed. Use both side of the plate so it maintains the same height.

Good idea with the pedals. I think I'll try the same thing.

Where did you find an 8t sprocket?

[yerfdogman]

I got the 8 tooth at this site
http://ombwarehouse.com/-40-41-Chain...h-AZ2182K.html
it is for a size 40/41 chain and it is smaller in structure. I would have rather had one for the 40 chain only, with about the same dimensions as the original sprocket, but it does work good and i am happy with it. The only difference between the 40 only and the 40/41 is the width of the teeth on the sprocket. The 41 chain has a little smaller width than the 40 so naturally the 40/41 sprocket teeth are not as wide as the 40 only. This is the only 5/8, 8 tooth, 40/41, c-hub sprocket I found for a reasonable price. They do have 40 only in the b-hub which I found at northern tool website. I also found a 40 only c hub on ebay but it was 4 times as much. I have the yerfdog 3203 which has the 40 chain, check and make sure what you have before ordering so you get the right one.
It does take off and climb a lot better now.

[Old_Dog]

Originally Posted by yerfdogman

I got the 8 tooth at this site
http://ombwarehouse.com/-40-41-Chain...h-AZ2182K.html
it is for a size 40/41 chain and it is smaller in structure. I would have rather had one for the 40 chain only, with about the same dimensions as the original sprocket, but it does work good and i am happy with it. The only difference between the 40 only and the 40/41 is the width of the teeth on the sprocket. The 41 chain has a little smaller width than the 40 so naturally the 40/41 sprocket teeth are not as wide as the 40 only. This is the only 5/8, 8 tooth, 40/41, c-hub sprocket I found for a reasonable price. They do have 40 only in the b-hub which I found at northern tool website. I also found a 40 only c hub on ebay but it was 4 times as much. I have the yerfdog 3203 which has the 40 chain, check and make sure what you have before ordering so you get the right one.
It does take off and climb a lot better now.

Thanks for the link. I guess that confirms that I have the 3203. The sprocket I bought fits 40/41 and it is thinner than my stock sprocket.

[yerfdogman]

It shows how I moved the pedal back to where my kid can reach it. This does not fit in my truck with the tailgate up so I got some B-Line straps and put them on so it is easy to hook the ratchet strap to the buggy. I have two on the front and 2 on the back.

[metalstudman1]

Great job on the pedal mod. Your son looks all nice and toasty! no socks?

[yerfdogman]

I have the engine governed down, the remote kill switch under the steering wheel hooked up (and showed him how to use it), seat belts and helmets on, and I always ride with him as well. He should have had his socks and shoes on but he snuck it by me. Thanks on the mod comment, hope it helps out others who are debating on what to do.

[Old_Dog]

I just thought I'd follow up with the results on this thread since I started it. I ended up installing the 9t sprocket and replacing my green spring with a yellow one. I know I should have done one at a time, but I just wanted to get it done. So, I can't say which was more effective, but between the two mods, the cart is now useable. Before, it wouldn't go up even a slight incline and I had to get behind and push.

My son can now climb the hills on all the grove roads on our property. It's just barely enough power to get to the top, but he's only 9, so he's happy with it.

Thanks everyone for your advice.

[Newoldstock]

Anyone have any information on this spring?

Story goes this fits over the green or yellow torsional spring in a 30 series secondary and aplies more force to close the clutch.

I would like to see some images and hear about this if anyone has tried it.

215272A. GOLD SPRING- COMPRESSION

[metalstudman1]

So is the buggy still performing?
I'd like to see how it could fit over the spring!!! do you really need to add more force/HP on the clutches performance to open the driven slower and downshift faster?Belt wear? overheating clutch?

[Newoldstock]

Not buggy......

MB165 using buggy parts.
That's why I came here.
I figurered buggy experts would have some insights that might help me.
Lacking the spring in question I have started to make my own springs.

And yes, clutch presure at this point.
You guys with stock engines are not pushing things this hard.

I turn a belt into crumb rubber in under an hour......
Here is my prototype Gold type copmpression spring.
http://www.oldminibikes.com/forum/ph...0-0691&cat=500

[metalstudman1]

MB165 is a mini bike w/ a 165cc? Sorry this started out as a buggy thread! Something is wrong if you're cooking a belt like that. You have to be a member to view the link.

[Newoldstock]

Originally Posted by metalstudman1

MB165 is a mini bike w/ a 165cc? Sorry this started out as a buggy thread! Something is wrong if you're cooking a belt like that. You have to be a member to view the link.

Sorry about that I forgot.
Here's a walk around on Youtube.
http://www.youtube.com/watch?v=EkxXq...1&feature=plcp
Same drive components as the Yerf Dog 3203.
9 tooth primary drive to the same 54 ratio sprocket as the Kart.
Same primary and secondary clutch.

Engine is a clone however and not the Tech motor the dog uses.
Displacement is a little less at 196cc, but its been modified a little.

Something wrong about turning a belt to crumb rubber in under an hour lol?
Ya lol.
There is lol......

The 9 tooth primary drive though is a great thing to do for added low end torque.

There is still a problem it was factory tuned for an engine making 9 pounds of torque at 3600 rpm.
And I think everyone with a kart or bike using these things is exceeding the torque or speed ( and usualy both ).
Net result is the clutch transitions too soon and does not have the amount of clamping force on the belt handle the extra power.
The belt slips once its fully transitioned and its actualy riding high ont he primary further limiting the contact between the primary sheaves and the belt as well as making slip worse ( and rapind belt wear ).

Solutions:
Still working on that.
softer primary springs may help with the early transition as well as cranking up the secodanry tension.
But ultimately I think the second mystery gold spring Comet made was deisgned to increase the clamping force and retard the trasnsition from high to low ration and increase the clamping force on the belt.

Hard to say though not a lot of discussion and information on how to tune these and there is a very limited stock of parts to work from.

See here on this ebay auction.
http://www.ebay.ca/itm/Comet-20-30-S...item519fba1407
This fellow has posted a chart indicating what springs and weights were avaiable at one time.
Some of these obviously were for a 2 cycle aplication, maybe the Chrysler westbend engine used in the Rokon back inthe 60s and 70s...
In nay event having access to these parts might make getting the clutch to run more in that intermdiate possition of not fully open or closed for most of the time easier to achieve.

MIght try and put some rosin on the belt too to see if it will bite a little harder and reduce the slip.

Next stop.
A salasbury 340 if I can find such a beast because the 40 series will not bolt to the engine ( unless there was a 3/4 inch version driver I am not aware of ) or a far more expensive clutch deisgned for Jr drag racing.

[metalstudman1]

Rosin on a belt may help grip, but when it gets too hot it will try and ball up. In my experience- for a belt to dry out and crumble there's far too much heat around the belt or when a belt has a lot of whip it get's dried out very fast. A belt that slip's alot get's glazed on the tapers. The idea that a salisbury clutch is going to provide better performance on a near stock engine is a stretch! Though tuneable- you may get slightly better ratio due to the size/diameter, but as far as shifting and response there won't be much difference.I think you'll spend a bunch of money for little performance difference- but it's your money!!

[Newoldstock]

Well my belts are not glazing or dried out.

See picture of this belt after about 45 minuts of tuning runs, never exceeding 4500 rpm.
http://www.buggymasters.com/forum/al...pictureid=1589

Notice the abnormal wear.
This groving is I suspect caused by some slip when the belt reaches the end of travel and ius riding high in the primary. And it wears its fastest.

Heat has not been an issue as far as I can tell.
Everything works well.
and everything is lined up before you ask.
Too within .010
I went to the trouble to cut some shim plates into washers to get as near perfect alignment as possible.

Near stock engine and power maybe throwing 8 hp at it I think.
I have a clone with the potential to make a not inconsiderable amount of power.
But I am not using all its potential, the real power doesn't come untill after about 3600 rpm and I may be aproaching peak torque at 4400.

[metalstudman1]

Sorry I don't see a suspect groove only the side of the bias belt edge. You've obviously witnessed the belt riding above the top of the clutch sheaves? The frayed edges in my experience is basically normal but could indicate a rough surface or riding too deep into the driven (possible rivet contact). When you said turn a belt into crumb rubber I assumed it to crumble!!! I understand your terminology now after viewing the pic.
So what RPM are you able to get out of that basically stock clone, 4,400rpm is impressive.

[Newoldstock]

Hard to see that grove but its there.
I have to do something about it.....

Ran a ridge this afternoon.
the belt has no ridge anymore since it spent more time between the sheaves than riding on top.

Maybe I need to look at some sort of adjustment to the jack shaft that lets me increase the C to C as the belt wears.....

Brass bushing jambed up in the moving sheave.
More troubles I need to adress.

4400 is not that impressive.
A basic stock clone can do near 5000 for short sprints.
http://www.youtube.com/watch?v=EqYou...0&feature=plcp
This engine was known to reach 5000 rpm now and then even with a governer

Guess I should mention some details on the engine.

Tillotson 7/8 venturi carb ( stock is 5/8 )
ZM4 flat top piston.
ARC billet rod.
GXV 160 aluminum mower flywheel.
Can with a little more lift and durration.
Ported 14cc head, complete aftermarket valve train.
Header .880 ID 20 inches long.

Now just because you have power on tap does not mean you need to use it all the time.
Most of these modifications were made to ensure the engine would be strong and reliable under all conditions. All the weak points have been adressed.

Hmm rivet contact eh?
How would I check that?
Any sugestions?

[metalstudman1]

well!!! your engine is far from stock!!!!!! you can't expect those RPM's from a stock engine.
To see if your belt is hitting the rivets in the driven- at the bottom of the driven is rivets holding the sheaves, if they're shiney then the belt has been making contact(fraying on the bottom edge of the belt). When at WOT for extended length the belt will try and go deeper into the driven and bump the rivets.

[Zapper]

I have a hammer impact that works real good they are not to much cost wise if you donot have air.

[Newoldstock]

Hmm,
I'll have to watch for that.

In the previously posted video * small boy yells look at the maniac go *.
Thats a much earlier engine this is for all intensive purposes stock.
It has stock internals and a governer.
It has a header and some minor carb work.
Might even be a high compression 14cc head ( cant remember ).
But its nearly stock, behaves like stock, bolt it on a log spliter and it will split logs like stock...
The kicker is these engines need some help for reliability and proper perfromance.
They are too lean out of the box. timing is slightly retarded, exhaust and airbox are significant bottle necks to good opperation.
But if you fix all that its still stock and runs better than new.

Now my not stock engine could turn all the way to 7000 rpm if I asked it and it won't turn into shrapnel.
But thats not what it was built to do.
Most of the time it will work no harder than a stock engine.

This was a race bike.
I think its racing days are behind it now, the way my back feels today I know mine are.

Even with the clutch issues it climbs like a monkey, but the torque converter is a bit of a dispointment. Its not any better at what it used to do with a clutch ( gearing will likely change that ).

[Newoldstock]

So I decided to experiement a little and try and replicate what I thought the gold spring might look like and how it would work.
http://www.buggymasters.com/forum/al...pictureid=1632
And now for the real deal.
Left to right Chinese green spring Green spring yellow and finaly the gold ( notice its wound reverse )
http://www.buggymasters.com/forum/al...pictureid=1633

specifications.
stock : .117 wire, 2.025 OD, 2.425 long, 4 coils

green : .113 wire, 2.110 OD, 2.980 long, 4 coils

yellow : .128 wire, 2.075 OD, 2.860 long, 4 coils

gold : .141 wire, 2.060 OD, 2.770 long, 4.75 coils

Special thanks to a friend in the USA who snapped up the very last gold spring anyone is aware of from the same vender I I dithered and lost out on.

[Newoldstock]

Took some practice but I made some springs that show a lot of promiss.

My gold spring inspired helper spring will get tested this weekend.