Re: Prepping for the 1st build
When I first installed the motor on my bike I was really disappointed in the amount of drag and mechanical noise it added while pedaling. I found as I rode that the tension of the chain as applied by the tensioner had a lot of effect on how much noise and drag the motor chain caused. Too tight you get lots of noise and drag, too loose and you will get chain hop and might have it pop off on you or even jam up and break.
I was lucky enough to be able to adjust my bike to run without the tensioner, once I got rid of it my bike pedaled like a bike again, no significant drag or noises from the motor chain. Not every bike can be rigged this way, sometimes the frame or other parts interfere with the chain if you loose the tensioner, sometimes it's not possible to properly position the motor and rear wheel to tension the chain properly without the tensioner also. However, if you can make it work without the tensioner you will not regret it. My chain isn't particularly tight and it has run without issue for about 800 miles so far without the tensioner.
Best bet is probably to build her first with the tensioner, get used to it and then re-assess the possibility of loosing the tensioner after you have some experience with the bike. That way you will appreciate the improvement the most as well, like me. I was so thrilled the first time I rode without that damn tensioner!
Some people have taken me to task for suggesting this, so I figured I should tell you to build with the tensioner first... If it is important that you limit the drag so you can pedal easily it might be something you want to try....
Also, not sure if you have already, but make sure you run a good chain. Most of the kit chains are pretty poor quality, I like #41 industrial/farm chain, but there are other lighter weight upgrade chains that will work well also.