Hello there dave31,thanks for replying!
I am thinking of building one but will be going long distance to work everyday so i need reliability and power for hills(i live in a mountainous area)!It will be a mountain bike probably from bikes 2 u direct in england (have look at the cross speedster blue or theraleigh freeride at10) !4 stroke to keep noise down also and i am looking for speeds of around 40mph.
I know that honda have great engines and have been looking at the gx100 so any advice on any of this from you would be greatly appreciated