Track Tac

Need some chain help

T

Time Bomb Tom

Member
Can someone tell me the differences between 40, 41 and 420 chain and sprockets. I have a 40B drive sprocket and it seems a lot wider than the axle sprocket. What do the A, B and C designations stand for on the sprocket? Width?

Thanks
 
A chain with a letter designation is industrial/farm implement, slow speed stuff, and should never be used on a kart.
The 40B sprockets are an odd-ball width (7.2mm) and you would have to go to 428 chain, which would actually too wide, allowing the chain to wonder side to side.
That stuff should probably should be left at the farm implement store, not used on a kart either.

Back in the mostly 2-stroke days there were always someone trying to use cheap #35 industrial chain on a kart, instead of actual kart chain, and it would start locking up after a couple of heats.

Save yourself some trouble, and stick to stuff made for karts/bikes. It will be cheaper in the long run.
 
Ok, so here’s the deal. I’m trying to finish up my yard kart project. I transplanted a 22 hp v-twin onto it and am running a Salisbury torque converter off a snow mobile. That runs the jack shaft and the only thing I could find to run off the shaft to the axle was a 40b sprocket. My #40 chain is actual kart chain from BMI. I also have some 420 and 428 motorcycle chain. Neither of these fit the 40b sprocket at all and the 40 chain binds up on it. Any ideas on where to find a 14 tooth driver on a hub with a 3/4” hole?
 
Well, I don’t recommend doing this, but I pulled a po boy trick. I chucked the sprocket in the lathe and took .0015 off the outside edge, then tapered the teeth on both sides and knocked a tiny amount off the tips. It now fits the 40 chain without binding. It worked for a couple test passes, but it’s not a permanent fix. I looked and found a new rear and a 14 tooth #41 driver from BMI and they are currently in the shopping cart.

Thanks for the help.
 
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