The quad was just bought a couple weeks back and it seems to run good but has a bad vibration when it’s running in high speeds and worse when you let off. We adjusted the valves it’s not that. I thought it was the front sprocket because that’s where it sounds like it’s coming from that was fine. I read a thread that said it could be the clutch is going bad all the fluids are up and it has good compression and the crank is solid. Any info would help thanks!

 

Check wheels for being bent, plus rear axle for being bent. How is the chain? Tight and slack spots can cause vibration. Don't know the internals of an EX engine, but most Honda singles of over 250ccs have a harmonic balancer, if it was fitted a tooth or two out, you would get bad vibrations, but would feel those in neutral as well.

 

Thank you it does it in neutral it’s a friends quad I have the same one his has a terrible vibration when you rev it and when you let off it’s in the engine. So we adjusted valves and it’s no better I’m thinking it’s the piston. We are going to check the compression. The crank is solid we tried to wiggle it with the side plate off or it could be the clutch. Thank you for your time.