Topic: 78 cb750F - smoked the clutch

[Geeto67]

so my clutch is slipping. I was playing with some squids two nights back on the highway on my 78 cb750F and when I whacked the throttle open the bike rev'd and went nowhere. by the time I got home it was feeling like she was done - and smelled like it too.

so I am going to order new barnett fibers. Yes I kno about the barnett springs and stock fibers but really I need more clutch - the motor is overpowering the stock clutch with the RC springs I have in there now.

So my question is - can I use barnett fibers with stock steels and my Rc springs or do I have to spend the money for the barnett steels an springs as well.

Also if the plate is not warped but discolored, should I replace it? in the past I would have but I am feeling kind of stingy right now.

[scondon]

 I have a extra Barnett steel at home and compare thickness to stock steel tonight. If they are the same I would just clean the stock steels with a scotchbrite pad and some mild solvent(simple green?). The Barnett fibre plates do stick very well with a high HP engine and I haven't come upon the reported downsides yet(14,000 miles).

[mystic_1]

Also if the plate is not warped but discolored, should I replace it? in the past I would have but I am feeling kind of stingy right now.

I probably would.  Once you heat metal to the point where it changes color, you've altered it's physical properties such as tensile strength etc.

mystic_1

[TwoTired]

Discolored steel from heat means a change in temper or hardness.  The hardness effects the wear characteristics.  A friction steel that wears unevenly or has changed hardness properties just can't be good.

To draw a parallel to automotive. When oil drops got on flywheel steel, there would be hard spots on the friction surface of the plate where clutch dics made contact and slipped.  You couldn't turn these down on a lathe cause the steel at those spots got too hard.  You had to grind off the hard spots first and then turn the flywheel flat again.  If the spots were too deep or the cracking too severe, the flywheel was scrapped.

I don't think there is enough material on a MC clutch steel to grind off the changed temper steel and still maintain near correct thickness.

But, I suppose you could try it and let us know how it worked out after 10k miles or so.

Cheers,

[Geeto67]

don't know if any got that hot yet....haven't taken it apart yet....just getting ready since we had the same problem on a buddy's kawi h2 and we ended up replacing the steels.

[Tower]

Discolouration and warping go hand-in-hand for the reason mentioned about temper.  I agree with the other sentiments, and would replace any discoloured steels.

The 1978 springs are already stiffer and longer than previous years.  going much stiffer has its drawbacks.

[eurban]

In the late clutches, there is notch at the end of the clutch basket fingers for a wider tanged fiber plate.  Are your Barnett fibers plates designed to work with the late clutches?

[HondaMan]

How to check your clutch steel plates:
1. Find a piece of glass that's bigger than the plate (steal one from a wife's picture when she's not looking, put it back later-that works around here...).
2. Clean the plate with acetone or other degreaser.
3. Lay the plate on the glass and try to slide some feeler gages between the plate and the glass at different points, to see how warped it is. Honda says .006" is too much, I think .004" is too much, myself. Especially with a good-running motor, the .006" figure is enough to use up the friction plates quick.