Topic: Clutch Specifications *Help* CB750K2

[Artfrombama]

Did a search, checked the FAQ's, and the honda4fun.com site is down.

I need the minimum working thickness for the CB750K2 friction clutch plate and steel plate. Also need the clutch spring height.

Thanks!

[Clyde]

Friction disc thickness .. 3.42-3.58mm
0.1346-0.1409 inch
Wear limit 3.1mm (0.122 inch)
Clutch spring free length ... 31.94mm
1.257 inch
Minimum limit 30.5mm
1.20 inch
Steel plates in clutch
should be renewed if warped more than
0.3mm (0.012 inch).

The above has been copied from a Honda service manual

[Artfrombama]

Friction disc thickness .. 3.42-3.58mm
0.1346-0.1409 inch
Wear limit 3.1mm (0.122 inch)
Clutch spring free length ... 31.94mm
1.257 inch
Minimum limit 30.5mm
1.20 inch
Steel plates in clutch
should be renewed if warped more than
0.3mm (0.012 inch).

The above has been copied from a Honda service manual

Damn!
Everything is within specs, frictions are .138-.142", spring height is 1.395"
Why would my clutch slip under full power in high gear? Engages right at the end of clutch travel. Adjusted the bolt until it lightly bottomed then backed off 1/8 turn.

Thanks for posting the info I needed, I owe you a beer!

[Tower]

Reasons why slipping, from most likely to least likely, are:
1) Adjusted too far out
2) Springs are too weak - Replace springs
3) Worn clutch disks - Replace thin disks
4) Glazed plates and/or disks - rough up with 400 grit paper
5) Warped clutch plates - Replace warped plates
6) Poor oiling - drill more holes in centre, unclog passages
7) Crack in clutch pressure plate - Replace pressure plate
8 ) Worn clutch throwout mechanism - Replace clutch inner cover / mechanism

Clutch adjustment and to some extent condition of the clutch cable and throwout mechanism determine whether the clutch engages early (just as you begin to squeeze the upper lever) or late (upper lever almost touching the handlebars)
- Lube cable, adjust per manual ensuring 1/4 turn out from just touching

Edit: K2 was a transition year for clutch design, so ensure you have the right components for your particular clutch.

[Artfrombama]

Tower,
     I appreciate you taking the time for the in depth clutch troubleshooting guide. I will check those things this afternoon.
      When I took the cover off I was impressed that everything was in good condition (not wrecked by a ham-fisted mechanic like everything else) indicating either the case has never been opened or someone that knew what they were doing was there last.
     I did notice the first friction plate (furthermost from the center of the bike) was a different design than the others. Another thing I noticed that I felt wasn't kosher was the innermost friction plate was against the aluminum clutch drum. From my diagrams it appears a steel plate goes in first, then a friction.
     Could the wrong oil cause a slipping clutch? To get the bike running I used some cheap store brand 10W40 oil.
     I'll report back later.

[Artfrombama]

Washed the parts up, the frictions were glazed up...Shiny as mirrors! A sheet of #80 emery paper on a piece of glass, sanded just enough to break the glaze. Sanded the steels too.
Back together and adjusted to the manual. All seems well.

Thanks to those that helped.

[Tower]

Choice of oil could make a difference.  The CB750's wet clutch works best with non-detergent motorcycle oils. Auto oils may not be the best as they could foam causing oiling problems.

The disk and plate configuration you described is correct for the early clutch designs.  i.e. disks were found at both ends of the disk/plate stack.  Also, the outer disk is larger so that it will fit properly in the wider basket.  Do not replace this outer disk with the smaller inner disks.

The early designs also had clutch inner baskets that were too restrictive in flinging oil out to the disks and steels.  If you find more than three holes in the grooves of the inner basket, your model is fine.  Fewer than three holes indicates a very early clutch design prone to burning and glazing.

I'm assuming that your clutch works perfectly now.

[Artfrombama]

I'm assuming that your clutch works perfectly now.

Weeeelllll....
No more slipping in high but engages right at the last 1/2" of clutch lever travel. Adjusted exactly to the manual. Aggravating as %$#*& starting off because I have a bad hesitation just off idle.

Once I get moving it runs like a bat out of hell!

6 of the friction discs were the same, aluminum with straight oil grooves. One friction disc was steel and the grooves were more circular. Same shape and thickness.

7 discs and 6 steels.

I'll play around with the adjustment maybe Sunday.