Topic: Air box gasket 1976 cb 750f

[Dreadnought]

Hello all this is my first post. I am working  an old 1976 cb 750 F. The motorcycle has been sitting for years. Is it imperative to have the air box gasket that seals the upper and lower half’s of the air box? If so I noticed that there are some oem gaskets available  for the K model. Is there a difference between the K model airbox and the F model? Also the gaskets that are available are very expensive Can I use silicone in lieu of the gasket? Any information would be helpful. Thanks

[BenelliSEI]

Don’t be afraid to get creative! A restaurant near me gets lots of supplies in different size plastic pails. The owner leaves them out back for those of us that like free stuff. Some pail lids have  a soft “0” ring fitted, to seal tightly when snapped in. I use them as large rubber bands and have cut them to length for just the job you describe! Glue your gasket to one 1/2 of the airbox, and it will be easier to install.

[BenelliSEI]

P.S. I’m not sure my ‘76 F had a gasket in there? The two halves just fit snuggly together? Maybe someone else will pipe in, I sold mine a few years ago.....

[seanbarney41]

I think it should be alright without.  The gasket is soft rubber and formed into kind of a complex profile, kinda like car door weatherstrip, so that it is retained by a channel.  once an old gasket comes out of that channel, it is nearly impossible to get it to go back.  I can't imagine a new one being much easier to install but have never had a new one.

[newday777]

Welcome aboard Dreadnought
From the parts fiche the K and the F use different part numbers for the seal, might be the same seal(?) but the F seal includes the metal divider above the seal. I don't know if they are the same or not as I've only had the K model bikes.

[newday777]

BTW
Vintagecb750.com offers an aftermarket seal for the K model airbox for $12 if you want to try that.

https://www.vintagecb750.com/products/6/fuel-system/53/air-filters-vent-filters

[4CM5]

I found one on EBay for my 1976 cb 750f and it fits.  Gasket Rubber, for Air Cleaner Housing, part number 17221-341-000 (for $15.00).

[Dreadnought]

Ok thanks all🙂

[madmtnmotors]

The gasket fits around the inner plate at the bottom of the upper half. Replacing the gasket is easier if you remove that inner plate:

http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000

[HondaMan]

After I thought about this, I realized that I once pulled apart an F1 airbox where the owner had apparently broken the OEM gasket, too. He made a new one in-place in the airbox using black silicone sealant, letting it set up for several days (he told me, later) before closing the box. It sealed perfectly when I replaced his air filter with a new K&N type. He had done that 'gasket' some 8 years earlier.

I don't think I am that patient with silicone?