Drive Shaft Completely Worn

Discussion in 'Transmission / Drivetrain' started by Louie, Jun 14, 2016.

  1. Louie

    Louie New Member

    Still working out all the kinks on my new engine. It's been running fine for a few days but yesterday it wouldn't start or even turn over and the clutch didn't seem to engage. Opened it up today and found that the shaft that the drive sprocket is on was completely worn down and the woodruff key was totally sheered.
    Any suggestions as to why this happened/what I can do to fix it? I'm trying to take apart the entire thing, but I don't know how to remove the shafts from either side. I've taken everything else off, as the pictures show.

  2. HeadSmess

    HeadSmess Well-Known Member

    shafts screwed, but is ok. just whack it with a hammer and it will come out, along with the bearing on the side opposite to the hammer whack... best to hit from the sprocket side, keep the bits for spares (theres a spring and stuff in the shaft, youll see when it comes out... though you will probably never need spares of them anyway).

    you dont need to tear the whole engine apart, so its pretty easy job.

    you gunna need new shaft, maybe sprocket, and a key.

    looks like it never had the key in the first place. pretty common :( fiddly to get them to stay in place whilst assembling, chinese factory worker dont care if it falls out, just pack and sell!
  3. Yeah I already ordered a new clutch shaft and various keys. Not sure if the key slot is going to be the same size on the new shaft, hoping I don't have to order a new sprocket as well. I also dropped the 8mm ball from jnside the shaft down a drain so I got one of those as well.
    The key was included but it sheared off which is why the sprocket started spinning around the clutch shaft.
  4. Nitram

    Nitram New Member

    A suggestion as to why this may have occurred. The cover plate over the drive sprocket only leaves less than a millimetre between the chain and the piece of metal of the cover. This is the piece between the two short cover screws. I install a load of these engines and when I first started dealing with them I had two issues with two separate engines, were the chain blinded itself between the sprocket and the above mentioned side wall of the sprocket cover.
    On both occasions I was only turning the wheel by hand and the chain locked up solid. If you were riding when this happened you may not notice this until the sprocket broke. I now cut the portion of the sidewall of the cover between the two screws, completely away. No further issues.
    Hope this helps.

    From your Irish Cousin. Cheers.

  5. jaguar

    jaguar Well-Known Member

    the woodruff shears off when the nut keeping everything snug gets loose
  6. Garyminor72

    Garyminor72 Guest

    Hi There, this is the closest suggestion to the problem that I'm having. I just want to make sure we're talking about the same issue. I was doing my random snapping of the bolts and screws as I do want a weekly basis and they noticed when the clutch is engaged with the clutch arm will slide up and down about an inch or two almost coming out of the case. When the clutch handle is pulled in the arm tightens up Through the Wire and does not slide around at all. I have removed the left side sprocket cover (3 screws.) And just have a greasy mess I'm not sure exactly what I'm looking for with the part of the clutch arm that sticks down on to the gear. I have noticed before that the chain will bind in that area we are referring to. I want to make sure that we are talking about the same issue here if so what parts need to be replaced? And can you send photos of how you make the cut to the case? Thank you in advance so very very much.
    P.s. they sell this as an 80cc motor in China it's really a 66cc 2 stroke motor. I eagerly await your response.

    Gary Minor

  7. Nitram

    Nitram New Member

    I have no photos. Just cut out the complete return of the clutch cover case BETWEEN the two small screws. This will allow a further 3mm space for the chain to go around the sprocket.
    The lever you mention will move up and down. This is not an issue.
    I suggest that you make the cut, clean off all the grease and reapply a small amount to the cog and the lever.
    I hope this helps
    You should need no other parts if your cog is ok.