Re: hi everone
I have a mountain bike without suspension too. I started off with the in frame GC 2-stroke, and now I'm running a 4-stroke friction drive.
I like the 4-stroke a LOT better! It's more reliable, and less hassle than the 2-stroke.
One thing about the in frame engines, they make the bike look a lot more like a motorcycle, which can definitely be a cop magnet! An engine on the back wheel doesn't draw the same kind of attention.
Maybe something to consider if there is any legal problems in your area.