Topic: clutch issues cb 750

[kenzie]

I have read all the posts on clutches still no luck. Replaced the clutch plates and tried to do the proper adjustments, when I put the bike in first gear it lurches forward and stalls, this is while I have the leaver fully engaged.when I did the adjustment behind the clutch cover the adjustment screw turns in 3-4 turns with no tension on it, I think its bottomed out. That doesnt seem right to me but who knows? Sure could use some advice. thanks again

[Jonesy]

What year 750?

Did you reinstall the steel plates all in the same direction?

Did you soak the new friction plates thoroughly in clean oil before you installed them? The plates will swell a bit when soaked, and if installed dry they can play havoc with the adjustments.

Did you turn the adjustment screw all the way in until you felt resistance?

This may be helpful: http://www.salocal.com/sohc/tech/clutch/cth1.htm

[kenzie]

Its a 1973, I never soaked the plates in oil, maybe I should try that, When I turned the screw in it went in probably 4 turns then feels like it bottomed out. what does the adjusting screw do when you turn it in?Is it suppose to compress something?

[Jonesy]

The 1973 model did not have the special anti-rattle plate. (just checking) For proper adjustment you screw the adjustment screw all the way until you feel it bottom out. Then back it off 1/2 turn.

what does the adjusting screw do when you turn it in?Is it suppose to compress something?

Sort of. When you pull in the clutch lever, the cable pulls on the lever on the outside of the clutch housing, twisting the shaft sticking out of the housing. On the opposite side of the clutch cover, there is a steel disk with three ramps machined into it, and another steel disk with corresponding ramps on top of it that twists along with the actuator shaft. Between these steel discs are a set of steel balls that ride in the ramps. When you pull the lever, the one disc rotates relative to the fixed one, with the balls riding up the ramps. This moves the actuator inward, applying pressure to the clutch center and disengaging the clutch. When you turn the adjustment screw, you move the actuator in or out. You adjust it so the actuator just touches the clutch assembly (when you feel the screw start to bottom out) and then back it off a bit so it doesn't ride against the spinning clutch all the time, accelerating wear of the pieces.

[kenzie]

how tight are the 4 bolts that hold the springs in place suppose to be ? should they tighten up until they bottom out?

[Jonesy]

Yes. The bolts bottom out. The whole clutch assembly floats on the center hub, with the springs pushing the assembly forward against the face of the hub. When the actuator pushes the clutch pack inward, it pushes it away from the face of the hub against the pressure of the springs, releasing the clutch.

[kenzie]

Thanks Jonesy!

[Jonesy]

No prob.

The first time I took a 750 clutch apart, I was confused about how it worked, as all the other bike clutches I'd seen had the actuator assemblies on the opposite side of the crankcase, with a long rod through the mainshaft. Since this moved the rod towards the clutch, all is had to do was push the top of the clutch pack outwards, against the springs. the CB750 flips this design around, and in a very clever fashion- but it can be a bit confusing...

[Steve F]

Just a dumb queston, but how long has the bike been sitting since you put the clutch together and tried it?  Sometimes, the clutch plates get stuck together from sitting, and you have to try rocking the bike back and forth in gear with the clutch pulled in to break the plates loose.
Just a thought.

[kenzie]

bike only sat a few days since it was put together, I soaked the new parts in oil and double checked the way I assembled it, now just hope for the best!

[kenzie]

Put the clutch back together tried it on the center stand seems OK changes gears up and down, took it of the stand tried it and it still stalls even if you have the clutch pulled in when you shift into 1st, hoping its just an adjustment? anyone else run into this? Thanks again

[Jonesy]

Here's from the Honda shop manual, hope it helps:

[kenzie]

Thanks again jonesy Ill try not to bother you to many more times! think I am getting close

[Jonesy]

No problem. If you want I can post the shop manual pages outline the entire disassembly/inspection/reassembly procedure.