Re: Burning Rubber smell + Poor free wheeling
 

NTV is nice engine but it is not just because of twin sparks, it is also smaller carb chokes which usually help low-speed running at expense of high speed. Same with port design, what works well for low-speed charge mixing can hurt high speed gas flow.

But there is no reason SV should be rougher really, check carb balance and mixture screws. I like to set up mixture for highest vacuum, seems to run good that way.