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First gear stripped?

Discussion in 'The Garage' started by ToastLoader, Jul 30, 2015.

  1. ToastLoader

    ToastLoader XS400 Member

    Hey all... I've got a 1980 XS400g that I've been restoring to running condition. This is my first bike so I'm kind of learning as I go.

    I had the engine running perfect, but now I've run into a transmission problem...

    A few days ago, I went to accelerate from a full stop on an incline, and a machine gun sound came from the transmission and I could feel first gear slipping. If I take off easy with minimal power, it won't happen - but if I try to accelerate hard, it will start slipping again.

    Since I've had the bike, the gear shifts never felt super smooth, sometimes refusing to to fully shift into the next higher gear. I've adjusted the clutch at the engine and lever according to the manual, so I'm fairly sure the clutch is disengaging fully. Oil was changed recently with Yamalube.

    Full Disclosure: I did lay it down once when I forgot to put the kickstand down. :doh: The only visible damage was a slightly bent shift lever and a scratched mirror.

    So I think my transmission is hosed. I've decided to look at this as a learning experience and try to fix it myself, so I was hoping someone could clue me in on what to look for when I get the engine cracked open.

    Thanks!
     
  2. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    Well the machine gun sound was most likely the dogs popping in and out. Slipping is slipping though, I'd take a look at your clutch adjustment again. I thought I had mine right for the longest time (by the book) but ended up being wrong. If you can't get it fixed there, start thinking about looking at the clutch itself. Check the push rod, make sure that's all kosher.
     
  3. bcware

    bcware Well-read Top Contributor

    I agree. I don't think you'd be riding in first gear at all if the teeth were gone; it wouldn't matter if you feathered it or not off the line. If your clutch is that badly out of adjustment you may have simply forced the transmission to shift "clutchless" this can definitely cause some alarming noises, especially if it was a downshift. Definitely check for plain old worn friction plates as well if it comes to opening the side covers.

    And just for giggles, what kind of oil are you using?
     
  4. ToastLoader

    ToastLoader XS400 Member

    I'm using Yamalube 15w-40.

    Thanks for the input guys. I'll definitely make sure the clutch is properly adjusted and for wear.

    Is there a trick to adjusting the clutch at the engine? I turn the adjustment screw in until I feel resistance, then back it out 1\4 of a turn. Is there a better way to do it?
     
  5. xschris

    xschris XS400 Guru Top Contributor

    10,445
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    I would recommend 20w-50 as the manual calls for. Also check your sprockets for wear and make sure the chain is adjusted to the correct tightness.
     
  6. bcware

    bcware Well-read Top Contributor

    Good call Chris, the chain adjustment can have a large effect; that extra slop on a loose chain does screw things up.
     
  7. ToastLoader

    ToastLoader XS400 Member

    Sorry, I double-checked and did use 20w-50 on the last oil change. My mistake.

    The chain and sprockets seem fine. I've measured the chain for slack and the sprocket teeth aren't worn.

    I went back and adjusted the clutch again - also replaced the clutch pushrod seal because of a slow leak. The pushrod was in good condition. After all that, it did seem to shift a little smoother, but still machine-gunned when any power was applied in 1st gear. 2nd - 6th gear can take full power, no problem.

    I guess next is checking the clutch?
     
  8. bcware

    bcware Well-read Top Contributor

    I would crack it open; just grab a replacement gasket before you dive in.
     
  9. ToastLoader

    ToastLoader XS400 Member

    Well, I guess I should look at this as a learning experience...

    I'll go ahead and get the gasket.

    Is there anything specific I should look for when I get in there? A previous poster mentioned dogs.

    Thanks for your help everyone. I'll likely update this thread when I get in there and look around.
     
  10. bcware

    bcware Well-read Top Contributor

    I don't think you can see the dogs by removing the side case cover; I think that requires splitting the case.

    You could check out the clutch basket and the friction discs though. It does sound like the dogs, however, if it is machine gunning consistently.
     
  11. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    Can you get a video of the noise?
     
  12. Wolfe_11B

    Wolfe_11B XS400 Guru Top Contributor

    I'm wondering if one of the gear snap rings went. That could cause the constant miss meshing. Drain a little oil and see if you have some metal coming out with it. If you see any, you are going to be pulling the motor anyway
     

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