79 cb750 clutch issue?

[cafeloco]

Hi all , I'm new to this forum, i recently picked up two 10th anniversary cb750s. one is a parts bike while the other is in better shape. i got them home and was able to fire the good one up. i went to take it for a test ride and it popped into gear fine but when i let the clutch out nothing happened (rpms dropped a little). i adjusted the clutch cable and on my second go at riding it the clutch engaged a little more but all i could get it to do was role forward very slowly. I'm totally new to these bikes, never worked on them before, but today i took apart some of the clutch and measured the springs and they were fine. everything else looked fine. is it possible that the wrong kind of oil being in the bike could cause it to slip like that (drained the oil to get at the clutch and it was pretty grimy)? or could it be something else entirely? theres still a possibility of the clutch just being worn out but i have to get the specialty tool to disassemble it completely.  

any help would be very much appreciated

thanks!

[cafeloco]

Anyone?

[LukeM]

Thanks for your patience.  Some of us have other stuff happening in our lives/careers. :-)

It would seem that your clutch is slipping.  This can be caused by:
glazed clutch plates/disks
improper lubricant
misadjusted clutch cable
worn clutch springs

These are not in any order.

Get the Factory Service Manual on the front page of our little forum, and check out the diagnosis and maintenance sections that pertain to the clutch.  They will tell you more than I could.

You're already checked the clutch springs.  I think there's a measurement spec for good vs. worn in the FSM.

Same for the clutch cable.

One culpirt is a previous owner using an automotive oil labeled ENERGY CONSERVING in this motorcycle.  Both the engine and the transmission/clutch use the same oil. This type of oil has some extra friction fighting compounds in it, which can cause problems with the clutch. I don't recall if just changing the oil will remedy that: usually, if it gets into the plates for some period of time, it's trouble.  Let's not consider that right now.  Check the other stuff first, then you can dig into the internals of the clutch itself.

Keep us in the loop.  We'll help if we can.
Luke M

[cafeloco]

Thanks luke

its not the cable or springs, i think its actually a combination of the wrong oil and the discs/plates being worn out. i still haven't taken the clutch apart cause i don't have the specialty tool (anybody know where i can get one? I've been looking without luck). when i drained the oil it looked like it hadn't been changed in a while, it was a sort of green brown color. also is there any chance that it isn't the clutch thats causing the problem?

thanks

[LukeM]

Try this:

Put the bike on the centerstand.
Block the front wheel with something substantial (garage door, car, side of house).
Start the engine.
Pull the clutch in, and engage first gear.
Let the clutch out.

If the wheel spins freely with no load on it (like the bike, and you), then you've eliminated the transmission, chain, sprockets, and rear wheel bearings.  You could also rev the engine in this gear, and see if the rear wheel speeds up accordingly.  If it does, then my best guess would be worn clutch plates/disks and/or clutch springs.

For those who have more experience with this scenario, please chime in.  

As far as the clutch pack removal tool, your best bet is to go to your Honda dealer or one of the online parts shops, and ask for it.  Here's an EBay link to the tool.

I hope this helps.
Luke M

[cafeloco]

so i tried that and the wheel did spin but not nearly as fast as it should have, it kind just turned lazily if you will and when i revd is spun a little faster but still not like it should have. thanks for the link! ill be ordering one of those..