Clutch issues...

[jakefromstatefarm]

Hi guys!

The clutch on my 1979 xs400 doesn't spring back out after its compressed and never has. Also, sometimes when attempting to kickstart, the kick will slip right through without engaging the crank, as if the clutch were still pulled in. One thing I've noticed and am skeptical of is that the rod that the clutch screw pushes into the gearbox isn't attached to the clutch screw. So essentially, once the clutch lever is compressed (which turns the clutch screw, which pushes the clutch rod into the gearbox), there's nothing to pull it back out of the gearbox once the clutch lever is released. Is this normal, or is the rod supposed to be attached to the screw somehow?

Takeaways -
1. How do I restore spring on the clutch lever?
2. Is the clutch rod supposed to be attached to the screw piece that the clutch line is attached to?

Sorry if my vocab is incorrect. Pretty new at all this.

Thanks!

 

[Joseph Lane]

Sounds like you have a few things to check here. I presume you have never been able to ride this bike?

Is the cable free to move when disconnected?

If you have the left side sprocket cover off, where the transmission attaches to the chain; does the shaft move inward with considerable force? You might need to use a 2x4 or something else to get a good enough push. It takes considerable effort to move a few mm. Is the rod dirty? Have you had the right side cover off to ensure there are screws and springs in the clutch assembly (I bought a bike missing tons of stuff inside)?

The black plug on the left side of the case near the chain sprocket is the clutch adjustment. It can be accessed with a 12mm deep well socket and a long thin screwdriver. Inside that worm gear assembly (inside the cover of course) is supposed to be a ball bearing mating with the shaft on the engine; is that missing?

I hope I'm not being too short on the issue but I've been through a 78 and 79 and had some problems along the way. You can't hold in the clutch and try to kickstart. That confused me a few times.

Let me know if I can be of more assistance.

 

[jakefromstatefarm]

Thanks so much for the quick and sincere reply Joseph. Nope - never ridden it. It wouldn't surprise me if it was missing parts (it wouldn't be the first part). The cable will move, you just have to manually pull the lever back out. I put a different set of handlebars on so the clutch line will definitely need readjusted. I'll try to tackle that tomorrow.

Do you mean push in the crank shaft at the front drive sprocket? I can try that tomorrow but I'd be surprised if it budges. The rod is perfectly clean. I've had the right cover off and I think it's all there and in order. The kickstart works and you can walk the bike up and down the gears.

However, I'm thinking I'm missing some stuff inside the worm gear assembly on the left side clutch cover. There's a ball bearing in there, but it just bumps the rod's end - doesn't grab onto it. The rod is a little bit smaller than the mouth that the ball bearing rests in.

If I don't hear from you before I spend some time on it tomorrow I'll upload some pics so you can tell me if I'm missing something.

Thanks again!

 

[Joseph Lane]

Sounds like you have a few things to check here. I presume you have never been able to ride this bike?

Is the cable free to move when disconnected?

If you have the left side sprocket cover off, where the transmission attaches to the chain; does the shaft move inward with considerable force? You might need to use a 2x4 or something else to get a good enough push. It takes considerable effort to move a few mm. Is the rod dirty? Have you had the right side cover off to ensure there are screws and spring in the clutch assembly (I bought a bike missing tons of stuff inside)?

The black plug on the left side of the case near the chain sprocket is the clutch adjustment. It can be accessed with a 12mm deep well socket and a long thin screwdriver. Inside that worm gear assembly (inside the cover of course) is supposed to be a ball bearing mating with the shaft on the engine; is that missing?

I hope I'm not being too short on the issue but I've been through a 78 and 79 and had some problems along the way. You can't hold in the clutch and try to kickstart. That confused me a few times.

Let me know if I can be of more assistance.

 

[Joseph Lane]

I might not have been clear. You can see the shaft for the clutch that the worm gear assembly pushes on when the left side sprocket cover is off. That should push in as that is the shaft that actuates the clutch assembly on the right side of the bike.

You should also use the bolt/screw adjustment that is under the rubber on that left side sprocket cover to adjust the clutch play. There is another adjustment on the handlebar lever of course, but that that should be adjusted later.

Furthermore there should be a spring attached to the worm gear assembly on the left side sprocket cover plate.

If all of that is in place then you should be alright. I have heard that the clutch actuation shaft can become dirty from chain slime and stick which would cause it not to spring back. Same is true if the spring is not attached to that left sprocket cover to spring back the worm assembly. The ball bearing being in place means you are most of the way there. I have to adjust my 78 clutch in the morning so I could take a few pictures if you need.

Joseph

 

[Joseph Lane]

Furthermore. You can pull the push rod all the way out of the left side of the bike. I cleaned mine off and oiled it as it was a bit dirty. I actually cleaned a lot of sandy slime off it which helped too. Otherwise you can also lube the clutch cable which may cause problems if it isn't new. Mine has a teflon insert that can creep up into the bare cable that actuates the left side handlebar lever. I think that covers all the issues I've heard of.

 

[BBS360]

Lots already mentioned but something needs to be cleared up: the clutch screw/wormgear does not pull the clutch rod back. At all.
As you mentioned the ball bearing in the mechanism just barely makes contact with the rod. It is doing what all bearings do and reducing friction while allowing the clutch rod to rotate freely. There's another bearing on the other end of the clutch rod. Together they keep any motion from the spinning clutch cage from transferring along the clutch rod.

It's the clutch springs that compress the clutch plates and also push the clutch rod back through the crankcase.

As mentioned, do the full clutch adjustment procedure and check on that spring. The manual suggests rotating the screw under the rubber cover back 1/4 turn after feeling it make contact but some members find 1/6 of a rotation back works well (1 face of a hex nut).

 

[jakefromstatefarm]

SWEET. Sounds like a plan. There have been so many times that a thread discussion on here helps my brain's light bulb to go on. Finally understand how something works feels so good. You guys are the best.

 

[jakefromstatefarm]

Joseph - if it ends up being handy for you, I would probably benefit from some pics. I have a feeling I'm missing the spring you mentioned that retracts the worm gear/clutch line.

 

[BBS360]

Found this from an old thread: