Topic: Fork Seal Size

[jmk]

I recently checked my vin# and engine# just to be sure and indeed I do actually have a '72 cb750 k2.

I ordered new fork seals and they are too big.  The new seals have the right inside diameter, but the wrong outside diameter.  My old seals OD measures ~45.5mm (I don't have my calipers on me today..damn) and the new seal OD is ~48mm.  This 45.5mm OD makes sense seeing that the diameter on the actual fork looks to be around 45.5mm also, although without calipers this is hard to tell, does anyone have an old seal they can measure to check?

Anyway, it seems I might have different forks on my bike despite the fact that everything looks stock(fender, caliper, wheel, etc, at least I think).  Does anyone know what year the forks changed and is there anyway of telling what year mine are from?  Can I just get a seal matching thickness, od, and id, or is that asking for leakage?

Thanks for any thoughts or comments.
-jm

[mattcb350f]

According to the Honda Microfiche, the 72' seals have the 48mm outside diameter. When I checked the 69 750K0, they had seals with a 46mm outside diameter.

1969 Honda CB750K0 Fork seal #:
OIL SEAL (35X46X11)
91255-292-003

Somewhere in there the size changed, maybe exchange them for seals for a 69?

 Matt.

[markb]

I was just working on the seals on my K0 and ended up with the larger size too.  I found that after 1039120 they went to the larger size.  You must have early K0 forks.  I ended up with part number 91255-300-013 although my parts book shows 91255-292-003 also.

[mattcb350f]

  strange.

This would be a good question for HondaMan...

[754]

Early forks have a differemt radius where the wider seal part blends into the rest of the fork slider. I did not realize there was 2 seal sizes..

 it really sounds like you got early forks.. check the black center of the brake rotor.. if the outer edge away from the rotor is a square edge..it is early..