Topic: Clutch issues

[andreasledet]

Alright, so I've been through most clutch threads on this forum and other forums with no luck about fixing this...

I'm working on a 76 CB400 Four with clutch issues.

The clutch cable has been slipping more and more for a period of time due to a rusty bottom clutch adjustment bolt which was slowly breaking apart, making the cable slack.

Now that one has been replaced with a new one, but the clutch still doesn't work. I've tried making adjustments at the handle, on the new bottom adjustment bolt and to the slottet adjustment screw behind the triangular cover, but it still doesn't work.

When I put the bike in gear (engine off) I can't push it, and still can't push it with the clutch lever fully pressed, no matter how many adjustments I make to the three different adjustment options.
(That's how I've been testing it as the bike currently lacks a battery).

I'm thinking it might be the clutch plates, but I'm hoping it's not...

I should also add that the kick starter has been slipping (moves but doesn't turn the engine) in some clutch adjustment settings - leading me to think the issue might be related to both? - but currently it turns the engine, but the clutch issues persist.

I'm pretty much a rookie when it comes to bikes, so any help would be much appreciated.

Thanks in advance!

[andreasledet]

I should also add what effect I've been getting from turning the slotted adjustment screw:

When I turn it fully CCW (out), the handle goes very soft and had almost no effect on the clutch mechanism. When I turn it fully CW (in), the handle seems to have a big effect on the clutch mechanism but is also very hard to press - too hard for it to be drivable, almost. Not much luck trying in-between positions.

[Bodi]

The clutch lifter mechanism is fairly simple. Are you certain all parts are present?
Under the triangular cover you see the actuating lever and its return spring, and the slot screw and nut attaching it.
The mechanism inside the main clutch cover is a spiral ramp unit that pushes in on the end of the clutch pack centre when the lever is pulled up by the clutch cable. The ramp doesn't move in and out much at all in the lever's travel. The screw is used to set its movement so that it is just barely not pushing on the clutch release bearing when the lever is all the way out. That way the hand lever motion range should be able to fully disengage the clutch.
You should set the hand lever cable adjuster and the clutch end cable adjuster so that there's a slight slack - a bit of hand lever movement before the clutch end lever starts to move. Then adjust the screw - you can feel when it turns the ramp unit enough that it's starting to press on the release bearing (it gets very hard to turn). Tighten it to there and back off a bit, tighten the locking nut. That's properly adjusted. If the hand lever is hella stiff, the cable needs lube, is worn out, or is not routed properly. Misrouting can make the lever incredibly stiff.
The kickstarter turns the gearbox input shaft. The clutch is between it and the crankshaft. If the kickstarter slips, the clutch is slipping. If it slips with the clutch adjuster set loose - the clutch is in bad shape and needs attention.
You can take the clutch cover off without draining oil (oil level is way lower than the bottom of the cover) but you will need a new gasket if it's been on for years or decades.