Re: Bite the bullet
whatever you do, don't let it get you down. Sometimes these motors can give you a real hard time.
I have replaced the crappy 415 chain that comes with the kit with a 41 chain from Tractor Supply Co. If the chain is a little long use some spacers at the rear motor mount to move the motor forward. If there is an inch of slack in the chain you will only need to use 1/4 to 1/2 inch spacers on the mount. This will allow you to be rid of another piece of frustrating equipment, the chain tensioner. The right amount of tension on the chain negates the use of a tensioner and when the chain stretches you can remove a link if needed or add another spacer on the rear mount.
good luck and happy motoring
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." - Thomas Jefferson