Transmissons, Sprockets and Chains Ohhh Myyy!

B

Bohemian_Lady

New Member
Okay so aside from the goofy title, I already have a transmission on the way, its getting mounted to my Honda 35 gx. Now I just need a sprocket for it, the sprocket that I was told would fit is this one which is a 12 tooth for a 410 chain. Great but all I have is 415H, my wheel sprockets are all for 415H chain and I'm really not interested in buying new ones.

I searched ebay and could not find a drive sprocket for 415 chain that has the right interior measurements (The smallest being 11MM and the largest being 14MM). I did however find a 12 tooth sprocket with the proper interior measurements for a #41 chain. Is it possible to make this work with a 415H chain?
 
41 chain is 1/4" between the inner plates.

415H chain is 3/16" between the inner plates.

410 chain is 1/8" between the inner plates.

Obviously a little machine work will get a 415 chain on to a 41 (or 420) sprocket.

A 415 chain will fit on a 410 sprocket, but the fit will be a little loose.

The problem is the chinese seem to have trouble measuring things. China girl engine sprockets are .140 wide. A sloppy 415 fit. You may get a "41" sprocket that fits just fine with 415 chain.

Running the 410 sprocket is not the end of the world either- but it will wear faster than a full width sprocket.

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Mmm food for thought, thank you. Just one question, how much faster do you think a 410 sprocket would wear? Are we talking about the sprocket becoming unusable in two or three thousand miles or a couple hundred? For reference the sprocket on my 49cc china girl has 4700 miles on the same drive sprocket, there's doesn't seem to be a significant amount of wear.
 
I would build it with a 410 sprocket if that was what I had. That should give you plenty of time to find the right sprocket - I have run 40 chain on 420 sprockets without issues.

Given the beating a shift kit bike takes, I would say thousands, not hundreds.

B
 
Cool thank you, in that case I'll just go with the sprocket that I know will fit the transmission. Get her up and running then I'll have some time to either get a a sprocket machined, modified or ordered. Thanks muchly!
 
If you're machine shop challenged, I have made the thicker sprocket work by mounting it on a shaft and grinding it thinner with a 4" angle grinder. Spin it as you remove material and you can get good smooth results. It's time consuming but allows you to use the thinner #415 chain on #410 sprockets in a pinch. Keep it nice and cool with frequent dunking during grinding.
This ONLY works on STEEL sprockets! Most aluminum sprockets are hard anodized and grinding removes the wear surface leading to very quick wear and failures.
 
Thanks for the advice maniac, I'll stick that one in my tips and trick folder in case I need it. Fortunately I know a couple people with machine shops that would be willing to help me out with something this small.
 
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