Topic: K0 clutch won't disengage

[Turbogrimace]

I'm working on an early 1970 K0 and the clutch will not fully disengage. The outer basket does not have a ring welded to it so it has a separate outer ring that's supposed to be situated over the outer friction plate with smaller splines.

I've tried pretty much everything. I tried 6 frictions and 6 steels but the stack height wasn't enough. The inner hub is 41 mm. 7 frictions and 6 steels gets me to 37 mm, which I believe is the stack height for a 41 mm inner hub. I've tried it without the outer ring installed, with a different smaller splined friction, with a different pressure plate, with a different clutch cover and throw out, with different springs, etc.  I've adjusted the clutch lever every which way. On and on.

If I install the pressure plate without springs, there's enough room to free up the disc's and allow the hubs to spin separately. With the springs in, everything stays locked. I even cranked the clutch lever adjustment stud all the way in to see if I could get it to disengage fully at any point, but it still had a heavy drag (but less). I couldn't squeeze the hand lever any further. I had either reached the full extension of the throwout or something was hitting.

I attached a few pictures. The outer basket, the clutch assembled with the ring, and the clutch pack with the ring installed. Someone had attempted to put new fibers, steels, and springs in, but it didn't look like they tried to run it.

I'd really appreciate it if someone just told me I'm missing something obvious haha. It needs to be on the road in the next week or so.

EDIT: All the internals from a K5 were swapped in, including the outer basket. The same problem exists, but its less. I already tried the steel plates from this engine in the K0 setup, but it didn't help. I've tried multiples of every piece including covers.


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[Turbogrimace]

Forgot to mention that if I take the cover off and manually push the plate in, the clutch works just fine. I'm baffled.

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[PeWe]

Later or earlier clutch cover?
Top is later. It is modified with additional breather.
Under an earlier without the mechanism pushing clutch.

[smee]

How does the basket look? Any major grooves?

[69cb750]

Forgot to mention that if I take the cover off and manually push the plate in, the clutch works just fine.

This means the ramp is not working or not in contact with bearing, try another cover.

[Don R]

 Are the ball bearings in the clutch lifter?

[Turbogrimace]

@Don R yessir

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[Turbogrimace]

@69cb750 I've tried three covers. I've actually tried multiples for every piece. Including the outer basket, which is now from a K5.

I swear it has to be in the adjustment or steel plates. The plates that came with the engine were new but burnt in multiple spots. I swapped them with the set from the K5 which had some discoloration and mild pitting from sitting for years. I scuffed them down to smooth, but didn't take all of the color transferred from the fibers. As for the adjustment, I've even cranked the throwout pin all the way in to where there was no slack on the clutch lever and it was already pushing hard on the lifter plate. It still wouldn't fully disengage and the bike would roll forward and bog the engine down.

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[Turbogrimace]

Later or earlier clutch cover?
Top is later. It is modified with additional breather.
Under an earlier without the mechanism pushing clutch.

Hey Pewe. It's an earlier cover. I tried the cover off of a k5 and a k8 with no change.

@smee no grooves just a bit of discoloration. I've tried 2 different internal and external baskets.

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[newday777]

Later or earlier clutch cover?
Top is later. It is modified with additional breather.
Under an earlier without the mechanism pushing clutch.

Hey Pewe. It's an earlier cover. I tried the cover off of a k5 and a k8 with no change.

@smee no grooves just a bit of discoloration. I've tried 2 different internal and external baskets.

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I think when you change covers you have to change to the matching basket, especially on the K6-K8 covers. I'm not sure on the K5 if it is compatible with the K0 basket or not.
But being able to get the clutch to work without the cover tells me that the rod length is probably wrong??

[69cb750]

I swear it has to be in the adjustment or steel plates.

Assemble the clutch part by part from the parts diagram, use original parts, assume nothing.
A 69/70 clutch uses six friction plates.

[Turbogrimace]

The throwout pin is making contact and adjusts properly. If it was too short, I'd run out of thread. I think the part number for the throwout parts is the same for all years. Only minor differences in the clutch cover.

When I had the k0 setup in there,  I set it up exactly as the diagram showed and the stack height was too short. Odd odd odd.

I set up the k5 per the diagram too. 

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[Turbogrimace]

I have to correct myself. The k5 diagram shows a steel plate going in first against the inner aluminum backing. All diagrams on cmsnl show this setup up until 1976. This would mean it's a 6 plate system. Are these diagrams correct?

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[Don R]

  If we were playing a game of stump the chump, I'd be the chump because you did, and checked everything I can think of.
  I have an F2 clutch basket, discs, hub, carrier and plates working in a K1 engine with its old K1 cover, (it was chromed and matched the rest of the motor) I sanded the ribs and dimple on the inside for clearance. It is missing the snap ring but otherwise it's all F2, even the double riveted disc in the middle.

 My new Ebay friction plates were supposedly Honda nos, but I doubt they really are, they had clutch disc material all over the tabs and I had to sand all sides and edges on the tabs because they hung up going in. I matched the stack of parts shown on Partzilla for the F2.

[69cb750]

Download original parts manuals -
http://manuals.sohc4.net/cb750k/technical_reference/PL750K1_K2_1.pdf
http://manuals.sohc4.net/cb750k/technical_reference/PL750K1_K2_2.pdf
http://manuals.sohc4.net/cb750k/technical_reference/PL750K1_K2_3.pdf

Get an original shop manual
https://www.ebay.com/itm/175267419939

Friction disks are .122" to .140" measure yours, replace if not in range
Shop manual page 52 step #2 Assemble the six friction disks (outer diameter 151mm clutch plates and the clutch center into the clutch outer and then install the clutch outer ring.
(Order is friction, steel, friction, steel ...)

Step 3 Assemble friction disk B (outer diameter 148.5mm)

I have rebuilt 12+ 69/70 engines, these instructions are correct.

[Turbogrimace]

I have the shop manual and everything is in spec. Steels are flat, fibers are 1.3 ish. Springs are a hair under 32 mm, etc. I'm going to beat the tar out of it on some backroads and pray.

[smee]

May be slightly stupid, but is the clutch cable the correct OEM length cable? Is the adjustment correct? When you free up the clutch, does it work fine then?

[Turbogrimace]

May be slightly stupid, but is the clutch cable the correct OEM length cable? Is the adjustment correct? When you free up the clutch, does it work fine then?

I appreciate any thoughts and contributions.  Stupid or otherwise. The clutch cable seems to be fine. The lever at the cover moves the same distance as my other bikes. I'm actually running the adjustment for the throwout pin tight instead of 1/4 turn out.

When you say "free up the clutch," what do you mean? If you're talking about neutral, neutral rolls fine. If you're talking about disc9nnecting the cable, it stays locked up, if you're talking about something else, well, I'll need some clarification hahaha.

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[Don R]

 My kz1000 had 50wt Kendall oil in it, that stuff would literally glue the clutch together. I could tie back the lever for a while of stick a screwdriver through the oil fill hole and pry the plates apart. 

[Turbogrimace]

So. I took it out. Hammered on it. Let it cruise, whispered sweet nothings at it, and it loosened up. Difficult to shift from 1st to 2nd at a stop and find neutral, but shifting on the move is smooth. No more pull in 1st gear with the clutch in. K5 basket setup. I tried to break in the K0 like this and it wouldn't budge.

But I found another issue. 2nd gear jerks the bike around on occasion. Not like it's popping out and coasting, but rather a firm jerk of the bike. Bad gear? I'm sure that's it, but I just don't want to say it. Someone else give me the news.

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[ekpent]

It sounds like the gear dawgs might not be engaging on the first and second gear and slipping. Symptoms usually show themselves under acceleration and when it gets worse if that is your issue it will kick out to a false neutral. As for getting into neutral or any shifting on the bike for that matter things work better on these while the rear wheel is turning a little.

[Turbogrimace]

It sounds like the gear dawgs might not be engaging on the first and second gear and slipping. Symptoms usually show themselves under acceleration and when it gets worse if that is your issue it will kick out to a false neutral. As for getting into neutral or any shifting on the bike for that matter things work better on these while the rear wheel is turning a little.

Agreed. I've had worn out shift dogs before and it would fully pop out,sometimes with a little grind. 2nd gear engages with a clunk and under constant load, accelerating, but not heavily, it jerks. Never dropping out to a false neutral so far. But ionly put about 10 miles on it. The paint is still curing on the fender, so I'm riding around without it and the seat acting like a fender. This could be worn dogs, but its presenting itself differently than what I'm used to.

My little hotrod 750 is back cut and I love the way it engages.

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[HondaMan]

This sounds a bit (to me) like the oiling isn't quite happening between the plates?

I have (sitting on  my bench tonight) an actual K0 inner hub with NO oiling holes in it, came that way (bike had 8k miles was all, and on 3rd clutch, said the owner). I replaced the battered-up hub with a better one that actually had the oiling holes and it works fine (plus I added sipes to feed the holes as shown in my book).

[Turbogrimace]

This one had oiling holes at least. Now my concern is 2nd gear. It jerks like downshifting without clutching. If I accelerate hard, it stays in sometimes. Under a lighter load it jerks. I guess it's just slipping temporarily from worn dogs, but not completely falling out to a false neutral.

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[HondaMan]

This one had oiling holes at least. Now my concern is 2nd gear. It jerks like downshifting without clutching. If I accelerate hard, it stays in sometimes. Under a lighter load it jerks. I guess it's just slipping temporarily from worn dogs, but not completely falling out to a false neutral.

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Do the steel plates still look like those in the first picture of this thread? If so, I might suggest steel-wooling those dark spots off the steel ones where they are so dark. They get rusted like that from sitting (I see it a LOT in the engines that come here) and this will make the cork stick a little bit to the steel rust grit.