I'm new to this forum. I just bought my boys a used 1986 Moto-4 225 for Christmas. Red and black. Its the best looking old quad I've ever seen!! The guy I bought it off of took great care of it, so it looks as though its only a couple years old. Everything works great on it, but it makes this funny noise when its in gear. Its hard to explain the noise. Kinda like a vibrating, humming noise. Its more pronounced when its in high gear, still there but hardly noticable in low gear. Everything shifts well, plenty of power and torque. Mechanically it seems to function fine but I need to pin point this problem and fix it before it damages something. Its shaft driven, so I'm thinkin maybe a bad bearing or universal joint?? I don't know. Any suggestions?

 

Could be a universal joint I guess, they don't go out very often on quads though. You're sure it's not just the tires humming or something like that?

 

Nah, definetly not the tires. The noise comes from the left side of the motor where the high-low-reverse lever is. Thought I'd throw this out there to see if anyone else has ever run into something like this. I guess maybe I'll order a repair manual and open it up and see whats what. Any ideas or tips will help out. Thanks for replying

 

Nah, definetly not the tires. The noise comes from the left side of the motor where the high-low-reverse lever is. Thought I'd throw this out there to see if anyone else has ever run into something like this. I guess maybe I'll order a repair manual and open it up and see whats what. Any ideas or tips will help out. Thanks for replying

 

The only other thing I could think of other than the universal joint is that there's a bearing on it's last leg somewhere in there.

 

could be the clutch??..... I have a 86 moto4 200 and the engine is no good if you ever need parts, just ask

 

might check the timing chain tensioner, I took mine out the other day and did not put it back in right and it was winning real bad. I had to take it back out and reset the spring and put it back in, not only was it easier to put in, but the noise went away.