too fast too early?

[stretchintha420]

so i was on my way to work the other day with my grubee starfire 66 cc. im on my 3rd tank of gas so when i saw a coworker going the long way on his Harley i thought id give her some and take a shortcut and see if i could beat him there. well anyway as soon as i got on it, i got about 3/4 throttle and 32 mph i started hearing a knocking sound and lost 90 percent of my power. not wanting to toatly kill my china girl i hit the kill-switch and started to pedal. while i was peddaling i could still hear i slight knocking noise and my chain was significantly looser with my tensioner in the same place it always is.
any help were to start looking would help. im assuming its in the bottom end somewhere.
if it helps it will start and run it idle fine i can even rev it without bogging down. crank case??? please help out a noob

[2door]

If it was still making the noise with the clutch disengaged then the problem isn't in the crankshaft/piston. Suspend the rear wheel and turn the pedals while you listen for the source. I'd start with the chain since you say it suddenly got loose.
Tom

[stretchintha420]

Originally Posted by 2door

If it was still making the noise with the clutch disengaged then the problem isn't in the crankshaft/piston. Suspend the rear wheel and turn the pedals while you listen for the source. I'd start with the chain since you say it suddenly got loose.
Tom

thanks, im gonna have time to tear it apart tomorrow, ill try that first

[socialdistortionkid]

Did the chain need adjustments?

[stretchintha420]

after taking the motor apart today i think that might have been the only problem, but I've been too busy to investigate the issue so i ordered a replacement motor from bfg. i took the top end apart today and all is well except for some soot on the top of the piston witch is probably just from the rich break-in mix. so as long as the starfire and the bfg motor is compatible i guess i got a parts motor.

[socialdistortionkid]

good on you if you bought a spare motor, not so good if you bought a parts motor. from your symptoms it sounds like a simple chain adjustment

[stretchintha420]

after removing my front and rear large frame adapters, it seems that i have snapped another motor stud. and i can only tap it so many times so, i at least needed a bottom end.and much to my surprise i almost feel that the bfg motor will be stronger than my grubee. it even sounds a little deeper. the only problem I've been having is it takes a long time to start. but that might have something to do with the old spark plug. i am going to pick up a plug and wire tomorrow