How to Solve Chain Stretch

A good 415 chain from a motorbike shop is a good investment but the stock chains on Grubees are pretty good these days. I take out as many links as necessary when new to get the chain quite tight. Then after a good day of riding it stretches to about its maximum and I can normally shorten it a bit more which is then final. I like to get it so eventually it has a good line over the tensioner wheel which I ALWAYS keep low down on the slider so it can't suddenly slip down and cause enough slack for the chain to get sucked into the drive sprocket chamber and lock up as happens if the chain suddenly slackens for any reason. The attached picture shows a 2-stroke with chain how I like it. Not too tight and not too slack with minimum deflection over the tensioner wheel. I use hard steel bolts for the tensioner bracket so the threads don't strip but the stepped bolt on the tensioner wheel is a stock special and I can't replace that so I know it can't be tightened too hard without stripping so I keep it at its lowest setting for added safety. I slide the whole tensioner backwards or forwards along the chain stay to get the tension right and once set it is usually fairly permanent after the initial stretch of first 60 kms.
When mounting the rear sprocket I take time to get it as true as possible but never get it so the chain is the same taughtness through one revolution of the 44 or 48T sprocket because no sprocket or chainring ever seems to be pefectly round.
 

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I replaced my chain with #41 roller chain shortly after I built my bike. The stock #415 was a very inferior product and you can get 10 feet of #41 for about $15, problem solved! (for me anyways)
 
#41 Chain

#41 chain is different than #410, works great on my setup. Some body posted the spec comparison somewhere else on the site. It is widely available here in the states, I can get masterlinks, 1/2 links... It is much higher quality than the junk chain they send with the kit. What are you running on your bike if not #410?
 
#410, as I understand it, is 1/2" pitch x 1/8" wide.
What's different with #41? Is it (hopefully) slightly wider than 1/8", but narrower than 3/16"? ie 5/32"

My kit came with 415H chain. I think it's 1/2" x 3/16" and is a little too wide, slopping around on the sprockets.
#410 fits the jackshaft sprocket, only the countershaft sprocket is a problem.

My countershaft sprocket won't take the #410 without grinding the edges of the teeth as mentioned - coming soon.
 
I used to have to replace every kit chain with a Yaban 415 motorbike chain which was the same pitch 410. They were $15 - $18 each back then but are now $40 so I don't buy them. The price rise occured same time as chains on Grubee kits improved. No chain fits some of those 2-stroke drive sprockets (especially ZBox) because they are machined so badly that no chain of any pitch would ever fit them. The variation in the sprocket is visible if you look carefullly at the attached photo. This one fitted no chain of any quality. Don't know about Grubee 2-strokes but I think their sprockets are machined in a better way. The ZBox ones were truly terrible. No sprockets or chainrings are perfectly round if they are made in China. The chain link lengths also used to be a bit variable as which will create problems as well.
In the pic the dark chain is a Yaban and the light chain is a ZBOX - both 410.
 

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#41 chain is 1/2" long X 1/4" wide. Works good on my set up but I am direct drive, no jackshaft. Looks like you're stuck with modifying your sprocket :(
 
IrishJohn said:
No chain fits some of those 2-stroke drive sprockets (especially ZBox) because they are machined so badly

John, you said 'especially ZBox', implying that you got better sprockets from elsewhere.
Where did you get the better ones? If I'm going to buy a new sprocket especially to grind the edges, I'd like to start with the best I can get here. (Might not even need to grind, then, to fit the #410.

Does anyone know if a Grubee sprocket will slot straight on?
 
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Chains dont stretch they wear, cheap chains will wear the connecting links after only a short time because of shoddy craftsmanship ie. holes not being perfectly round and pins. After that breakin period you should be good to go until usual wear wears down the pins and elongates the holes.
 
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