Topic: '72 CB750k clutch question

[Beav068]

Hello all,

I'm still getting the old girl back into shape after only being ridden for 15K miles in 33 years (poor girl).  In order to get to the performance issues, I must first take care of a very few operating issues.  One if these is my clutch.  No slippage or binding.  In fact, it works very well 99% of the time.

My problem is that if I use a full pull on the clutch lever, I run the risk of the linkage "going too far" and getting stuck.  As far as I can tell this is not the linkage, but the clutch cam somehow "over centering" so that the spring cannot pull it back to the ready position.

This is a PITA to have to deal with, and I would rather not have to worry about how much clutch I grab, so any suggestions on what might be out of adjustment or worn would be GREATLY appreciated.

Tim

[Jonesy]

Start by going over all the adjustment points.

Screw the cable adjuster all the way in on the handle grip. Screw the cable adjuster all the way in where the clutch cable enters the engine case. Take the chrome cover off the clutch and you will see the end of the cable where it attaches to the clutch release arm. There is a locknut on the pivot. Loosen it up and with a flat screwdriver back out the clutch center (counter-clockwise) until it is loose. Then, screw the center back in gently until you feel resistance. From this point on the center is trying to disengage the clutch, so as soon as you feel any resistance back the center off 1/4 to 1/2 turn and tighten the locknut. Now, use the cable adjuster on the outside of the engine case to take out the slack until you have about an inch of freeplay at the tip of the clutch lever. If you can't get it all the way out with the adjuster on the case, make the last adjustments with the adjuster on the clutch lever itself.

Another possible cause is the wrong cable. On another bike of mine, I installed an aftermarket clutch cable and experienced the same problem you have. It turns out the "exposed" or movable part (not the outer sheath) of the new cable was an inch or so shorter than the OEM Honda one, so by the time you adjusted for free play and such, it would pull the release mechanism too far, and it would jam. On the 750, all the release mechanism parts are inside the case, with plenty of lubricant, so I doubt any internal parts would be worn.

If you want, I can scan the part of the owner's manual that describes this procedure with pictures, if it would be of more help.

[Beav068]

Thank you VERY much for your help.  I think I recall the PO saying he had replaced the clutch cable, so perhaps he has the wrong one on there.  I will try the adjustments and see if that does the trick before you scan that thing for me.

Thanks again and I'll let you know how it goes!!

Tim

[Beav068]

Well sir, I did all of the adjustments and it appears to have corrected my problem!! :-)

Now, my next question is how much drag is normal with the bike in gear but the clutch pulled?  I put it on the cs and tried this, and it doesn't move as freely this way as it does in neutral.

Thanks again for your help!

Tim

[Jonesy]

Well sir, I did all of the adjustments and it appears to have corrected my problem!! :-)

Great action- glad I could be of help!

A bit of drag is normal. It will seem a bit sticky if it hasn't been ridden in a long time, or it's only ridden once a week or so. If the bike has been laid up for a spell, it can take up to 2 weeks of regular riding to fully free it up. I've seen some bikes run on the center stand in gear with the clutch pulled in and the rear wheel will spin- and only the brake stops it from turning. As long as the bike doesn't stall when put into gear or try to creep forward with the clutch pulled in and brakes released, you should be OK.

[Beav068]

Yeah, my wheel seems to "creep" on the cc with the clutch pulled in.  I have also noticed that since I adjusted the clutch the bike wants to "bounce" (for lack of a better term) as slower speeds (under 40 mph).  At higher rpm's/speeds it seems to go away.

Oh well, just one more thing to work on. :-)  My wife is jealous already, but as I explained to her, the CB is easier to turn on and always puts out her best effort when I DO turn her on.

Tim

[78_SaltLick]

my wheel spins also on the CC when its in neutrual. Not too fast, but it does rotate. I thought that was normal. guess not.

[Jonesy]

Yeah, my wheel seems to "creep" on the cc with the clutch pulled in. I have also noticed that since I adjusted the clutch the bike wants to "bounce" (for lack of a better term) as slower speeds (under 40 mph). At higher rpm's/speeds it seems to go away.

When I said creep, I meant when you're on the bike as if you were riding it and at a stop light (both tires on ground, in gear, clutch pulled in). If it feels like despite the clutch is pulled all the way in and the bike is still trying to move forward, the clutch is dragging. If not, you're OK.

When you say "bounce", you mean surging? Like someone's rolling the throttle back and forth? This might have been happening before, but the misadjustment of the clutch may have allowed for some slippage that hid the problem. You might have to make some carb adjustments or have some junk in the low-speed circuits of the carbs.

[Beav068]

No, the bike is fine on the ground, no creeping or stalling.  Just a slow rotation of the rear wheel on the CC.

I think the bouncing was actually surging caused by the plugs being fouled.  I replaced them and it seems to be taken care of.  The PO had a 4-2 crossover system that I took off and put the stock pipes back on.  He had never had it tuned to those 4-2 pipes, so I expected that it was probably running rich.

Tim