Originally posted by Voodo_Magic
Phew i thought i had done some damage then! just to clarify richen the bottom end 1/4 of a turn is turning the screw counterclockwise?
Yes. I say 1/4 of a turn to be totally safe but mayby 1/8th would be sufficient you need to get a feel for your specific engine. I usually do the middle needle when I am in a rush since you can access it easily through the rear window.
If your motor still has pinch at the top when hot without the plug it actually is not even run in fully yet.
To do a proper compression test you can do this:
1. Remove the motor from the chassis and remove pipe.
2. Spray a little fuel into the exhaust port and turn the motor over once or twice.
3. Roll the flywheel over while holding the exhaust port up to your ear. You should hear hissing which then stops as the piston nears the top of its stroke.
4. Hold it still before it fully turns over. You should not hear any hissing for at least 10 seconds. Less than 10 seconds is still OK but the motor is no longer in its prime.