Valve cover bolt rubber seals

[sr71cbx]

Hello all,
Thought I'd bring up the fact that Honda superseded the '79 CBX valve cover bolt rubber seals for the '80 and later ones(bigger OD).I had found this out when I did my engine swap last fall and had to pay the big bucks for a new valve cover gasket and bolt rubbers.They fit just fine and evidently seal just as good as the smaller O.D. ones for the 79 did when new,you guys that are doing a concours restoration on one of the '79's might check the local Honda shop and see about getting the NOS ones if they have some old stock left.

[John S. (5594)]

Hi Mark,

I just got through checking the valve lash on my black '80 and also noticed that there is a difference in the later (A Model) Cylinder Head Cover. Though I recall the eight thru-holes to be the same diameter - the surrounding seating area beneath the rubber mounting(s) is about a centimeter larger in diameter.

The OEM Mounting Rubbers on the later model are not just larger in external diameter (by about 6 mm) - but they are also thicker (by about 2 mm). For this reason - Honda specifies different bolt lengths for the two applications.

All of these parts are still available NOS (last I checked anyway). Since I recently purchased some replacement parts - I have the P/N's and pricing (here from www.servicehonda.com in USD):

90541-422-000 Rubber, Setting (Z Model) $3.85 each (8 required)

90543-422-000 Rubber, Mounting (A Model) $3.59 each (8 required)

90017-422-000 Bolt, Special (6 mm) (Z Model) $2.86 each (4 required)

90017-422-003 Bolt, Special (6 x 34 mm) (A Model) $3.17 each (4 required)

90038-422-000 Bolt, Special (6 x 38 mm) (Z Model) $4.10 each (4 required)

90038-422-003 Bolt, Special (6 x 40 mm) (A Model) $7.08 each (4 required)

Since I was using the existing cylinder head cover - I did not need to replace the mounting bolts. (Note that the Head Cover Packing is unchanged between model years).

A poor snapshot showing the difference in the mount diameters:



There are aftermarked mounting rubbers available - I have no experience with them though. As frequently as I plan on removing the covers - I will use the OEM parts as long as I can get them. No leaks so far :)

All the best,

John
San Jose, California

PS - Where should I send my spare CBX cylinder block for a 3 mm overbore? No experience here - but someone mentioned LA Sleeve. I also recall hearing that Wiseco offers this service - is that correct?

Thanks in advance.