Topic: 1977 or 1978 air box gasket

[beemerbum]

Does anyone know of a source for the rubber gasket that goes between the upper and lower half of the airbox on the '77-'78 CB 750K?

[BenelliSEI]

There is a guy on EBay selling a new one and the centre “shelf/divider”. Last timeI needed one I used a gasket from a five gallon plastic pail of  some oil we were using on a piece of farm equipment. It’s a large “0” ring about 1/8”  in diameter, inside the lid. It’s a tube (not solid) and fit perfectly. Anything will do, maybe afew feet of the tiny fuel line sold for weed eaters? Or even a foam backed tape.

[newday777]

You need #12(not available from Honda)
But here is one on fleebay

https://www.ebay.com/itm/385167106564?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=VTDXD14zS-q&sssrc=4429486&ssuid=okhTUXaIQdO&widget_ver=artemis&media=COPY

[HondaMan]

There is a guy on EBay selling a new one and the centre “shelf/divider”. Last timeI needed one I used a gasket from a five gallon plastic pail of  some oil we were using on a piece of farm equipment. It’s a large “0” ring about 1/8”  in diameter, inside the lid. It’s a tube (not solid) and fit perfectly. Anything will do, maybe afew feet of the tiny fuel line sold for weed eaters? Or even a foam backed tape.

You're right about all those things, but with one [experienced] caution: the foam-backed tape method only lasts about 8 months. The gas fumes dissolve the foam! (No, I won't tell you how I know this....I'm supposed to know what I am doing...). Don't use EDPM weatherstrip, either. (Same disclaimer applies.)

[RAFster122s]

Would silicone fuel line work, sounds about the size of small radio control airplane fuel line...

[beemerbum]

You need #12(not available from Honda)
But here is one on fleebay

https://www.ebay.com/itm/385167106564?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=VTDXD14zS-q&sssrc=4429486&ssuid=okhTUXaIQdO&widget_ver=artemis&media=COPY

Thanks for the tip. Just ordered it.

[BenelliSEI]

It’s been a while since I worked on my K7 or K8 so perhaps my memory is failing? What’s the location of this gasket? Does it go between the fixed upper half and the bottom “bucket”  half of the air box? If so, why worry about it? If any air gets sucked in through that gap, doesn’t it still get filtered before entering the velocity stacks/carbs?

[beemerbum]

On the subject of the '77-'78 airbox, where does the hose from the fitting on top connect to? My bike was missing the hose. It just seemed to be time to clean up parts of the bike and service the carb jets. As to why that separator and its hard to find gasket is there, I trust the judgement of Honda engineers that put it there. It seems any modification of the air system with pods etc. only decreases the performance of an otherwise stock engine and generates a multitude of posts on the subject

[BenelliSEI]

On the subject of the '77-'78 airbox, where does the hose from the fitting on top connect to? My bike was missing the hose. It just seemed to be time to clean up parts of the bike and service the carb jets. As to why that separator and its hard to find gasket is there, I trust the judgement of Honda engineers that put it there. It seems any modification of the air system with pods etc. only decreases the performance of an otherwise stock engine and generates a multitude of posts on the subject

I totally agree! But since the air box has a large hole to let fresh air into that chamber, I’m curious if that gasket really serves a purpose?