doritomiata
New Member
So I split my engine after observing an atrocious knocking sound and discovered that probably 3/4 of the needle bearing connecting the rod to the crank was destroyed and sitting in the bottom of the crankcase. I'm not concerned with repairing this engine; a new one is already on the way. My question is if any of you who are a little more versed in these engines could tell me what likely caused it to spin(?) that bearing.
Some history on the engine, I've had it for almost 2 years and ride this bike multiple times per week. I cut the skirt of the piston to match the intake port at TDC and raised the exhaust a little bit about a year ago. I've ran the stock carb with the stock jet which I believe is on the rich side, and the bike does 4-stroke pretty significantly above 6500ish rpm. I've also been running it with no air filter because it wouldn't fit on the bike, which I understand is stupid, but knowing what I know I don't think that would have caused the crank bearing to spin. The only other thing done to it was a high compression head and I ran it on 93.
I was full throttle topping out (around 6k-7k rpm) for a good couple minutes before it started knocking, and I'm not opposed to the theory that I might have just been stupid and blew the motor that way. No matter the case, if any of you could point to something that I should avoid on the next engine I would appreciate it, thanks for taking the time to read & respond.
Some history on the engine, I've had it for almost 2 years and ride this bike multiple times per week. I cut the skirt of the piston to match the intake port at TDC and raised the exhaust a little bit about a year ago. I've ran the stock carb with the stock jet which I believe is on the rich side, and the bike does 4-stroke pretty significantly above 6500ish rpm. I've also been running it with no air filter because it wouldn't fit on the bike, which I understand is stupid, but knowing what I know I don't think that would have caused the crank bearing to spin. The only other thing done to it was a high compression head and I ran it on 93.
I was full throttle topping out (around 6k-7k rpm) for a good couple minutes before it started knocking, and I'm not opposed to the theory that I might have just been stupid and blew the motor that way. No matter the case, if any of you could point to something that I should avoid on the next engine I would appreciate it, thanks for taking the time to read & respond.