My woodruff key fell out???

Discussion in 'General Questions' started by commanderroach1999, Oct 1, 2016.

  1. I opened up the crank case and in the purple grease I found a woodruff key. What is it? What does it do? Can I go without it? If not how to I reinstall it? I will try to attach a photo but it says low memory.

  2. Frankenstein

    Frankenstein Active Member

    Forget the picture. When you say crankcase I hope you don't mean you took the cylinder off and removed the clutch gears and magneto magnet and split the case. If you did and you found purple grease and a Woodruff key then return to sender and buy from a new vendor.

    Now I can only assume that by finding any grease (of the purple variety I don't know why but it's probably better than stock) you mean you opened the clutch gear side (right side if siting on bike) and found a Woodruff key. Well it's either a spare part (possible with Chinese quality control, consider yourself lucky it didn't get in the gears and turn them to mush) or its a key that unless you're finding slippage a problem shouldn't be investigated too far. The key is almost arbitrary since the shaft and mating gear is held in place by a taper along with friction pressure via a bolt or nut.

    If it's under the clutch gear area pull just the small bevel gear. If the Woodruff key is missing then install it and tighten the bolt back down again, if you have it off I recommend replacing with a hex bolt instead of the flathead screw bolt, it's usually the same thread as the magneto magnet nut.

    I recommend to do just the small gear since it turns counter clockwise, without a key it has the potential to loosen the bolt and stop the motor from pulling anything, on the large side the nut is automatically tightening the clutch onto the tapered shaft during use, so it becoming a problem is far less likely.

    It's very possible that the Woodruff key is an unexplained mistake, if found worse elsewhere, including a part of a completely distorted washer and a part of a zip tie inside of the magneto cover, it was making the bike discharge its cdi too soon and making a loud popping sound as an effect. The zip tie is still unknown to what and how it may of been involved.
    Nate888 likes this.
  3. crassius

    crassius Well-Known Member

    purple grease may also be found around the drive sprocket on left side, if you have the puller tool, it would be good to check all 4 keys to be sure they are there
  4. Holly

    Holly Member

    Sometimes the woodruff key, small bevel, stays put for weeks and sometimes it will pop out twice in a day. I super glue it back in place everytime. I have ordered new woodruff keys but going forward is there a better way to keep it in there? It's become a quick fix I've fixed it so many times now but I'm wondering if there's a trick I don't yet know about?
  5. Frankenstein

    Frankenstein Active Member

    Well either the key is too small, the keyway too big, or the bevel gear isn't seating properly, if left unchecked it can destroy the taper on the shaft and you'll need to replace the entire crankshaft... It happened to me unfortunately but now I'm much more careful.
    Holly likes this.
  6. Holly

    Holly Member

    I'm still using the original key it came with, but maybe at this point from wear the sizing has changed. I'll see what happens with the new keys. But it sounds like I might need to replace that setup. How about loctite? Is that stronger than superglue? I'll also double check the bevel when next assemble it.
  7. crassius

    crassius Well-Known Member

    if it came out once and spun a lot, the shaft may be too small now or there may be a ridge worn into it that doesn't allow the gear to seat all the way down - these both can be a hard fix
    Holly likes this.