Oh ya I forgot to add that you want the clutch RPM to start to grab right above idle to keep the power from yanking on the chain and freewheels. I removed a spring washer from each shoe so theres no spring preload on the shoe and I used shims to keep any play out. That got me to where the clutch starts to grab just above idle. On the very first couple test rides when the engine was cold the clutch had very slight drag when I first fired up the engine and after the engine ran about 30 seconds the drag went away. Then after a few test rides there was no drag at all at idle.
On a single speed setup you need a high clutch rpm to get you into the power band since you run a higher gear ratio on a single speed and you need the power to get rolling, on a shifter setup you have a much lower first gear and you don't need or want that kinda power or you will tear stuff up.
And I wouldn't use an SBP pipe, that's too small for this kind of RPM, you really need to use a 50cc dirt bike pipe, I found a new KTM 50 pipe w/silencer on Ebay for $70 w/free shipping. Good luck on your build and keep us up to date.
Heres a vid of the bike..... https://www.youtube.com/watch?v=m_j5y9XDyKw