Re: (Motorized Bike Kit) Good Chain Tension Setting rear sproket
Chain/sprocket alignment as well as chain tension is essential for a smooth running chain drive.
The tensioner wheel, if you must use one, must be aligned with the chain path. It can not pull the chain off to either side. Most, if not all kit tensioner brackets must be bent, or twisted to achieve this. The bracket as it comes in the kit does not allow for any taper in the chain stay and the tensioner wheel will be angled, not aligned with the chain.
The other big issue is securing the tensioner bracket so it can not rotate into the spokes. That has caused a lot of problems, both expensive and potentially dangerous for new builders. There are pages of discussion here on chain tensioners. Try the search feature and type in 'tensioner'. You''l have lots to read. Just make sure the bracket can't move. The best option is a bracket that bridges the seat and chain stay.
You'll want to maintain 1/2" to 3/4" of slack. To measure slack, engage the clutch, roll the bike forward gently until the piston comes up against a compression stroke. At that point the top chain run will go slack. That's the slack to be measured. Too tight or too loose will cause you problems.
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