Engine Trouble Clank sound

Discussion in '2-Stroke Engines' started by dotcom, Apr 13, 2016.

  1. dotcom

    dotcom Member

    All the sudden while riding I started to hear something wrong in the engine sounding like clank clank so I had to stop and ride home. After taking the cylinder off and piston, I realized it was not the needle bearing which is usually the culprit but this is apparently something more rare. Its not the piston pins either. I havent figured it out yet. Anyone know what the noise is? Here is a short video clip

    Last edited: Apr 13, 2016

  2. crassius

    crassius Well-Known Member

    if you feel it, then it could be a bearing grabbing & releasing, but could also be something in the teeth of the clutch's ring gear - did you check for clearance around rotor?

    doubt anyone here will have an answer without looking closely at it
  3. dotcom

    dotcom Member

    Yes its slightly felt. It does not feel like a piece of metal but rather a piece of something soft that occasionally gets stuck and grabs but it also makes a knocking sound. Crassius mentioned Clearance around rotor? Clutches ring gear? Bearing grabbing and releasing? I'm not sure if it's any of these but would love to know how to check each to eliminate doubts and get this rare issue resolved and the bike back on the road. Which rotor? And which ring gear? Hmm ID hate to have to get a new engine after this one had a balanced cranks and rode awesome for a couple months
  4. crassius

    crassius Well-Known Member

    you need to read some about these motors and the names of parts

    ring gear is big one on clutch side, rotor is magnet on other side - don't forget first check of prying up on each end of crank to see if mains are shot & letting it move up/down
  5. dotcom

    dotcom Member

    Small gear on clutch side metal fin piece broke and got wedged and stuck in between a big ring gear.

    Attached Files:

  6. dotcom

    dotcom Member

    Putting it all back together now and should be good now with a dab of grease until I can replace the small gear. Hopefully it will be ok and not even need a new one but now the small clutch gear is turning with a slight warp but i think it'll be fine. Thanks again , Jose
    Last edited: Apr 15, 2016
  7. crassius

    crassius Well-Known Member

    nope, the small bevel gear may be OK to run with a chipped tooth, but it needs to be reseated onto the tapered shaft - no big deal, as usually you can just loosen the bolt holding it with an impact driver, then put the flat side of a big socket on the gear and smack it with a hammer, tighten back down and watch to see if it runs true now
  8. Comandoriv

    Comandoriv New Member

    Please grease your gears!!! This could very well be a cause of gears running dry for a while.