Topic: CB500K2 Intake Manifold O-Rings

[Bear Four]

According to the parts list the O-rings for the valve  covers and the Intake manifolds are the same part number 91302-001-020.

They fit the valve covers well, but there's a big gap left on the intake manifold groove. I checked with a straight edge and the thickness of the O-ring is not giving a whole lot of crush.

This was an aftermarket gasket set and I am wondering if the original O-rings were thicker. I removed the originals, which filled the entire groove and still were a bit proud of the manifold flange surface. 

Does anyone have a NOS part for thickness reference. The new part is about 2.9mm thick, the old part is similar but fills the groove completely.  Unless these new O-rings swell with use I don't trust them.

Any thoughts or ideas?

[bryanj]

They fill the groove after being squished

[dave500]

aftermarket o rings and rubber gaskets always seem to be a bit smaller?

[Romhog]

I have come across this same issue. when checking CMSNL.com for example, they say they are the same part as you would use for tappet covers (which is 30.8 mm). When I try one of those o-rings, they look so flush already, I don't see how they will crush. what Am I missing here?

[HondaMan]

The OEM part is 3.2mm diameter. There are many substandard parts found in the common gasket kits, so I'm not surprised yours will not fit the intake manifolds. I use mostly Vesrah gasket kits: while they sometimes lasck an O-ring or two, the ones they supply more often fit the OEM specs. If you can't find some in the 3.2mm diameter, PM me, I have some.

[Nurse Julie]

They do squish out, I sell them on ebay and fit them to our own bikes, so I know they squish just fine... As long as you use Nitrile and not Viton.

[Deltarider]

They do. So far I had to renew only one.