Possible clutch problem

[gkmaia]

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[Re-run]

Well, it may just be a simple adjustment, check that first since it is free.
After that, a spring replacement might be in order. They are over 30 years old after all. You might also pull out the clutch basket and measure the thickness of the plates to make sure they are in spec. Those could be nearing the end of their life.

[TOOLS1]

Sounds like you need a new clutch to me.
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[gkmaia]

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[TOOLS1]

That is the "clutch adjustment point" adjusting the cables does not really do anything to the clutch unless that are way too tight, and then it will wear the clutch out. Usually when a clutch starts slipping the plates are BAD and need replaced. Unless the springs are broken in two they should be good.
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[gkmaia]

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[TOOLS1]

Let me see if I can clarify this. The cable adjustments do not actually adjust the clutch, they are just to take slack out of the cable that operates the clutch. The clutch adjustment is the adjuster shown in the picture you posted. What it actually does is adjust the actuating mechanism. Just like the cabels it must have some play, but not too much. If it is too tight it will wear out the throw out bearing, and the clutch will not fully engage making it slip. There is not any way to actually adjust the pressure on the clutch plates other then put in stiffer springs, and that will not cure bad/worn clutch plates, which is what you have.
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[gkmaia]

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[TOOLS1]

There is Physics behind what is happening. It's gearing, that is when your engine is making the most power, and pushing against the tallest gearing. Hence that is when your clutch is working the hardest.
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[gkmaia]

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[Rodgil]

I had the same clutch slip problem with my 1982 CB750F, and have the clutch apart at the moment. The plates are still good, but the clutch springs were stretched way past the limit in the FSM. Will source some heavy duty springs.
You can also check for free play at the lever on the outside of the clutch case, to see if you have run out of internal adjustment.
You shouldn't need a special socket to remove the clutch nut, if you are taking it apart. After unlocking the lock tab you can tap it undone with a screwdriver and mallet, or do as I did and notch out a piece of flat steel to make a two pronged spanner.
Also be sure you do not use a low friction oil.

[gkmaia]

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[Rodgil]

The Castrol oil is rated Jaso MA2, which is even better than Jaso MA for clutches, although either will do. The Moreys oil stabiliser has a friction reducer, and should not be used in a wet clutch bike. If an oil change doesn't fix the problem, you may have to pull the clutch to clean the plates, checking wear and clutch spring length at the same time.

[gkmaia]

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[TOOLS1]

NEVER use an oil additive with a wet clutch!!!!!!!! Or an oil with "Friction Reducers"!!!!!!!!!!
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[Re-run]

Clutches slip for 3 reasons, 4 in your case. The cable can be too tight causing a clutch to not fully engage. I have seen this personally. Which is why I suggest checking the cable. If the cable will not allow the clutch to fully engage, it will slip. I had a too tight cable on my fz when I got it and it made shifts very jerky till I adjusted it. Being a new clutch, it didn't slip, but it was worn some it probably would have.

Springs, if they are broken or have lost their weight, the plates will slip. Talked to many with this issue. Your springs have a service limit and once they are out of that, they need to be replaced. Most people prefer Honda springs. Barnett springs tend to be very heavy.

When you check the plates, you must check the fiber and steel plates. If any are close to out of service limits, just replace them all. Honda plates are best, or barnett plates. They are more, but the cheaper plates are just not as good. remember to soak them in oil overnight before installing and make sure the stamp patterns all go the same direction. You know how when things are stamped out of metal, there is an edge to it, this is what I am talking about.

A final note about oil. Virtually ALL oil has some sort of friction modifier in it. Very few do not have modifiers. What matter is how much and what it is. It is almost impossible to get away from this. However, it is not as hard as a person thinks it is.
Our bikes use 10-40, virtually any 10-40 will be safe as this weight and up of oil does not have the high levels that 10-30 and lower has. Another way to check is to look at the back and there will be a circle and if the oil has high modifiers, it will say energy conserving. If it does not, you are fine. Diesel oils are also fine and every bit as robust as any motorcycle oil. I seriously doubt a motorcycle tranny is a more harsh environment than a long haul semi diesel. So, choosing a safe oil is very easy. Choosing a GOOD oil is harder. That ends up being trial and error.

[gkmaia]

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[AndyS]

I have the same problem at 5000 revs in second gear only - what oil did you use

[gkmaia]

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