Folks,

My kids brought my favorite atv back to me this summer with a severe issue. A very loud noise was coming from the engine . I took the atv to a local repair man who replaced the clutch basket and checked value clearance. Needless to say he did not fix the problem and still charged me. I have a book and tore the cylinder and jug apart and removed the piston. The connecting rod on the camshaft feels good. I'm at a loss...maybe a bad timing chain? that seems tight along with the tensioner....I am putting in a new piston now. Please listen to the noise and tell what you diagnosis is.

VIDEO0043 - YouTube




Thanks Ed

 

Muffler Leak? Bad UV Joint? Thats my guesses

 

Also from what I hear the noise seems constant until the last rev you do in the video,

 

Sounds like bad clutch shoes and springs...When the engine revs up the sound quiten down...When engine is reved up the torque of the engine throw the shoes out into the the clutch drum....IMO Bad clutch springs in auto clutch [the one on the engine] not shifting clutch on transmission

 

Thanks for the advice...you may be on target...I did replace the clutch basket and the ATV was shifting with no problems. It does appear to be more clutch/transmission related. Cuurently I am replacing the piston. Once its back together I can pay more attention the the clutch. The noise is a loud "knocking noise" Its hard to tell if its eminating from the engine or the transmission. The noise is not in sync with the engine reving which may be a clue. Again I had this yo-yo atv repair guy replace the clutch basket for $150 parts and $150 labor....He also swapped out the shoes with the spring...I'm perplexed???

 

For those that tried to help me. I solved my problem. I pulled the jug..and cylinder head. I removed the piston and brought to my local machinist. He said cylinder walls were oval towards the bottom of the jug. He bored it out to 71.25 mm for $50. I purchased a new piston on Ebay for $50 and installed it....My repair manual was a essential need. Back in business without the noise

 

Glad to hear you got it fixed. I wish I was brave enough to tear into a motor like that....