30 series sprocket help

[shinwrx187]

5hp briggs, 30 series t.c, new coil, fresh fluids, new throttle cable, new throttle and break springs, new belt, I sanded most the rust off the clutch pulley so its real smooth. I Decided to take it out for a spin. Once it gets going it drives fine. When u come to a stop and you try to accelerate it doesnt want to move. Did not burn the new belt up. So i drove it around the block for about ten minutes and parked it back in my garage once i noticed it was making some slight grinding/vibration noises. I took a couple of pics and noticed there is no sprocket installed behind the torque converter thats hooked up to the chain! Its a round washer just like the one on the clutch that spins with the belt... I have posted pictures. I have no idea what type of sprocket i need to buy and install to connect to the chain. Im sure once i order the right part ill have to unbolt the engine some to get the chain on the sprocket and then move the engine back and tighten to complete the job?! Can someone please help me out?.. Thanks

 

[mckutzy]

I'm surprised it even moved...
The sprocket has had the teeth ground off...

Going to guess that it had teeth to begin
with... And now doesn't???

 

[shinwrx187]

I'm surprised it even moved...
The sprocket has had the teeth ground off...

Going to guess that it had teeth to begin
with... And now doesn't???

Lol that made me laugh good. How many tooth sprocket do u think i should order? I have no idea.

Im going to try and loosen the motor mount bolts to loosen the chain and gain access to the sprocket to see how many teeth are on it so i can look up a replacement to order. This kart has been sitting for a long time. Finally got the engine running good and go for a ride and the thing wont even barely engage..

 

[mckutzy]

Take a better look with the chain off... and see how many nubs if any are there to see what the same tooth count is....
What is the larger rear sprocket too count....

 

[shinwrx187]

Larger rear sprocket is 72 tooth. I took a picture of the smaller sprocket theres nothing left! Lol wtf I've never seen anything like it!

I measured the smaller sprocket and its 5/8. They sell 10 and 12 tooth rear sprocket not sure what i need for a 72 tooth larger sprocket, If i need to buy a new chain the one i have is pretty rusty, im sure i can clean it up but id rather not do all that work and have a chance of it snapping and not having a back up replacement or just a new one.

 

[mckutzy]

I can see 12 nubs....
Im going to guess thats a #35 chain..... that would go well if the rear is a #35 aswell....

What is the tooth spacing on the large sprocket???

 

[shinwrx187]

Just measured the tooth spacing on the larger sprocket and it is 1/4.

 

[landuse]

Then you have a #35 rear sprocket. If you get a 12T small sprocket, your gear ratio will be 6:1. A 10T (if you can get one) would give you a torquier 7.2:1

 

[shinwrx187]

Sweet! i just ordered a 10T 5/8 bore and i get it tomorrow just in time for the car show downtown here. More torque sounds good to me! Thanks guys for all the input!!

 

[mckutzy]

Just make sure it's a #35 chain sprocket...

 

[shinwrx187]

I get the 12T 5/8 sprocket tomorrow. The 10T 5/8 sprocket will be here sunday

 

[shinwrx187]

12T sprocket didn't work because it was 1/2 pitch.. To bad cause the bore was 5/8 and correct.. i just ordered the wrong part but thats my fault cause i didnt know what pitch it was but all #35 chains are 3/8 pitch. I recieved my 10T 5/8 bore and 3/8 pitch sprocket fits like a glove and is way smaller! So basically i have a 72 big sprocket witch came with the go kart and now ill install the 10T 5/8B 3/8 pitch #35 sprocket and should be more torque 72÷10 is 7:2. Ill post more pictures soon. Just have to fabricate everything.

 

[bob58o]

One of the best things I learned on this forum (from itsid iirc) is that the first number of the chain is the number of 1/8's" in the pitch.

#35 starts with 3. Pitch is 3/8"
#40 starts with 4. Pitch is 4/8". 4/8" = 1/2"
#420, #428, #41,.... all start with 4. All have 4/8" (1/2") pitch
#520, #530, 50H.... start with 5. Have 5/8" pitch.
60H starts with 6. Pitch is 6/8". 6/8" = 3/4"
80H starts with 8. Pitch is 8/8". 8/8" = 1"
100H would be 10. 10/8" = 1.25"

 

[landuse]

12T sprocket didn't work because it was 1/2 pitch.. To bad cause the bore was 5/8 and correct.. i just ordered the wrong part but thats my fault cause i didnt know what pitch it was but all #35 chains are 3/8 pitch. I recieved my 10T 5/8 bore and 3/8 pitch sprocket fits like a glove and is way smaller! So basically i have a 72 big sprocket witch came with the go kart and now ill install the 10T 5/8B 3/8 pitch #35 sprocket and should be more torque 72÷10 is 7:2. Ill post more pictures soon. Just have to fabricate everything.

Bummer!! We did mention that you had to buy a #35 sprocket several times though

 

[shinwrx187]

UPDATE: I've installed the 10T sprocket, put everything back together and it drives! The only problem I'm having is when u pull start the engine and it fires up. The crankshaft and clutch begin to spin and the torque converter ingauges so i basically have to hold the rear frame with my left foot on the drum brake so it wont take off on me and accelerate forward. I start it and try and run it choked so i can hopp on the kart and turn around and put the engine to run position without further issue. Also when I'm done driving and go to park the kart i hear some type of chain grinding or metal grinding until i completely choke the engine to kill the engine. Its the exact same when i stop the kart it wants to move forward even with the break completely pressed down and when i start it up it wants to take off on me. Other then that it drivea pretty good doesnt die. I have a brand new carburetor. I'm just not sure if i tightened the bolt to the clutch to tight or I installed something wrong i dont think so I put everything back together the way it came off and the belt is brand new has no signs of burning or damage or tearing. Does anyone have advice should i check the bolts to the pulley maybe i tightened them to much with my impact and its grabbing on idle? I tried adjusting everything, idle screws, clutch bolt, torque converter bolt and it still grabs on start or stopping like im at the drag strip. I also have a 12T on the way i should get this wednesday..

 

[Kent]

Are you sure the idle is set low enough??? It could also be you have a converter belt that is the wrong size. You can go to the tech tips on bmi and they tell you how to check your belt size.

Go Kart How To Guides and Go-Kart Manuals

www.bmikarts.com

good luck.....

 

[shinwrx187]

203589A is what i ordered. Its a perfect fit. Belt is facing the correct way never had an issue with it. Only issue I've had is the start or stopping gripping and pulling like holy sush! Basically will pull you if your not ready but u can hold it and keep it from not moving. I will mos definitely check the idle out that makes alot of sense. Ill put it on a couple jack stands and lower the idle as much as possible. Honestly i thought i would be able to burn the tires up on some grass. Ive been quiet disappointed so far with the power and output of this motor. But then again it been sitting for at least 6 months to 1 year. I know for a fact because of the condition of the inner pulleys ive clean everything up. Ill keep this post updated. Thanks for all the great information u guys have been a great help!

 

[landuse]

The wheels will always turn when up on jackstands. Set the idle when it is sitting on the ground. It shouldn't creep frward

 

[shinwrx187]

Yeah man i had to adjust the tiny screw on the throttle and the back tires stopped spinning, sometimes the throttle sticks a little bit but all in all i can now get on it and drive comfortably i install a brand new 3/4 pipe for exhaust and it sounds great! Brand new NGK spark plug! Purrs like a meowww now lol thanks alot guys this forum ROCKS!

 

[Crazznewt]

Yeah, especially with that 10/72 sprocket setup you might want to start it with a wheel chock blocking a wheel. My son started a kart the other day and the throttle stuck. That thing drug him several yards before he could hit the kill switch. He had tightened the cable housing into the throttle cable causing it to stick.