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Clutch drag (Pushrod/Cable/Adjustment?) woes CB500k2

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TimS-Orby:
Hi all,
After bowing out of the CB500k2 tinkering for a while, due to family health issues, I’m now back to tentative tinkering here and there.
Many thanks for the help regarding the carb service I undertook, and thanks to Nurse Julie for coming to the rescue with elusive carb parts. In the end that all went surprisingly well, and the bike now seems quite at home with the cleaned and serviced carbs. I’ve yet to do a full carb sync (I treated myself to a vacuum syncing setup), but so far so good, and we have a nice reliable tick-over.

So, it came to the stage where I was actually thinking about the first test run! No luck, I’m afraid. I soon discovered that the clutch was stuck solid. Anyway, after more reading here I managed to encourage the clutch plates apart and breathed a sigh of relief. I reckon it was maybe my fault as I had decided to do an oil change and I left her draining overnight… maybe the clutch plates had chance to drain just that bit too thoroughly?

There has still been no test run, because I have a real clutch drag problem. I had noticed when the bike first arrived that literally all of the free play had been taken out of the clutch cable. Literally zero freeplay, and it took me and all my strength to drag the clutch lever back. When I managed to drag the thing right back to the bars, I could actually drop her into gear with the clutch in without her jerking forward and stalling immediately. However, with the clutch in, and in gear, I could feel her trying to creep forward, and toeing her backward was like rolling over speed bumps! Clearly with clutch lever in it’s still pretty much engaged and, as I said, zero free play in the cable. It’s still the same now, unless I pull the lever all the way back the clutch doesn’t fully disengage. There’s no way I’d be happy to ride with the clutch behaving as it is, or feeling as it does.

Having done more reading here,  I decided to pull the left-side sprocket cover so I could have a look what was going on with the adjuster behind (I’d already tried all the adjustment strategies via the adjust etc). The adjuster looked pretty crappy, but the ball bearing was present and correct there in the thrusting bit. Ball bearing looks very clean and without scratches/flats.
So, I thoroughly cleaned the entire mechanism, spiral thread/splines and all, through roughly re-greased with high temp Moly grease, reassembled everything (making sure to include the ball bearing!), and it made no difference at all. I still have to crank all of the free play out of the cable at both ends to get anywhere near being able to lift the clutch to a level where the bike doesn’t stall when you drop it into gear.
I also thoroughly lubed the clutch cable and it runs freely and is routed as per recommendations here.

So, left-hand cover off again so I could have a look at the pushrod. To my relief it was in one piece, and to my eye it looks… Okay. Photos attached. However, it measures 256mm (at a push, possibly more like 255), and there is significant concavity on the adjuster end, where the ball bearing has been making contact. Now, is this divot in the end of the pushrod really enough to result in such a degree of clutch drag? If we say that this reduces the total throw of the pushrod by 1mm, is that enough to result in the kind of problems I’m having? What does everyone think?

I saw today that DS is actually selling some “Old Stock” pushrods, so I’ve ordered one just for the hell of it. They’ve clearly been in some mechanics drawer for donkey’s, so they’re rusty… but ordering one of those at least made me feel like I was doing something! Here’s the link: https://www.davidsilverspares.co.uk/CB500K2-FOUR-1973-USA/part_334326

Any ideas, anyone. Have I missed anything? Any advice?
Incidentally. In the documentation (such as it is) that can with the bike, I found a receipt from may this year for a “Repro” clutch cable from DS, which I’m assuming is the one that’s currently on the bike. What if this was the wrong cable… if the inner was too long, could that result in the adjuster/actuator not being lifter far enough when the lever was right back to the bars?
I don’t know, and I’m in that lonely place where you’re scratching your head about a job and you’re out of ideas, and need a hug! Lol.  I’m sure you all know how that feels! ;)

Looking forward to your thoughts,
Best,
T

Bryanj:
Pushrod looks fine, the adjuster outer can crack and that causes problems but by far the most common problem is a bad or incorectly routed cable unless a po has fitted extra stong springs.
Lubing a cable is a no no by the way

Seabeowner:
Clutch always was a little heavy on the 500, much lighter on the 550. If you have had it apart you should be familiar with adjusting the big slotted adjuster. It is very sensitive to a few degrees movement. I usually ignore the adjustment method in the manual and just play with this until it suits.

deltarider:
Is that a CB500K2-A (US)? What handlebars does it have, the high US or the low Europe ones? Reason I ask: Honda had two lengths clutch cables, for the US (suffix -020) and European handlebars (suffix -621). Could it be you have the wrong length clutch cable?
Genuine Honda clutch cables don't need to be lubed. Actually, it is not good for them.

TimS-Orby:
Thanks for the thoughts and advice All. Useful stuff.
I've continued to try adjustments of both cable ends and careful and small increments of the sprocket cover adjuster itself, but there's been no improvement whatsoever.
So, I decided my last resort should be to take my courage in both hands and dismantle the clutch pack itself. In the stuff that came with the bike there was a DS receipt for a clutch rebuild kit from 3 years ago, so I'm assuming that's what's in there now.
Teardown of the clutch has gone fairly easily... no broken springs and seemingly nothing untoward. However, I'm including photos of the plates, the friction plates and the steels in between. A few of them were stuck together a little, but I'm pretty sure it was mostly surface suction. BUT... should the steels be looking like that, or is that old material that needs to be removed from them? I'm assuming they should be pristine (ish) and shiny?
Oddly, the dotted pattern on them doesn't relate to any pattern on the current friction plates between them, so do we think someone used the old steels here, while replacing the friction plates? Advice please ;)
Anything else I need to know relating to these?
I've no measured the thickness of the friction plates yet, but understand I should.

Deltarider.... how do I know if my K2 is a K2 (A)? Is there any way to find out? I discovered it was a K2 from the frame and engine numbers. Just in case, I'm including a could of pics of the bars, but not sure if they will help at all.

Thanks for the help everyone.
Best,
T

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