Does your motor vibrate like hell when about half throttle or so? I just put a new motor and all on mine along with new U joints and yokes. Before I did this it vibrated a little but now man it's bad!!!! Once the motor is wide open it plains out but damn when it's at half throttle it feel like it's running a jack hammer.

The original yoke (that went from motor to the u joint) that was on this motor had two set screws the new one only has one set screw I'm thinking that this is the reason why it is so bad! Should I try to balance the yoke out or something?

O yeah and this is a GD motor to not a home made rig.

yep. just run it wide open and be done with it

mine is home made and like your's it vibrates pretty bad until about 3/4 throttle. Thats why I run it wide ass open.

could be bent shaft or unbalanced prop but if its like my 9hp lifan clone. it vibrates at just above idle. but i think it has to do more with the single cylinder slinging sidways. my 16 vanguard runs like a cadillac compared.

i had a 11hp tecumseh w/ vertical cylinder that vibrated at 3/4, the new greyhound 11hp w/ slanted cylinder runs MUCH smoother. course im sure thats mostly cause the greyhound has overhead valves where the tecumseh didnt...