Vacuum leak

[Pauarc]

Could this top seal be giving a vacuum leak as it’s damaged

[Martin6]

Possibly. A good bit of investigating there.

There is another thin rubber type gasket inside the screw top, so possibly not affecting how it runs.

[Pauarc]

A mate who used to work for a Honda bike shop in the 70s had some of the top grommets so carb are coming off to try them

[cbxman]

Hi Pauarc,

Interesting.  I was wondering about air leaks here.  I don't see a part number for that other than a "Top Set", but the drawing is unclear.  Unlikely, but do have 4 spare parts for sale?

Cheers,

Jerry

[Pauarc]

I’m going to see my friend I will see if he may have a part number l haven’t fitted them yet but he told me that they just prize and the new ones just push in

[JamesH]

Could this top seal be giving a vacuum leak as it’s damaged
[/quote
One way to ell would be to spray carb cleaner at the top of the carbs whilst running to see if that influences anything and could point to a leak.

[cbxman]

[/quote
One way to ell would be to spray carb cleaner at the top of the carbs whilst running to see if that influences anything and could point to a leak.
[/quote]

Yes but if have you wear on the rod in a position other than at tick-over, it might be difficult to detect if the seal is worn just enough to leak a bit at that point.
I'm thinking that maybe the most worn part of the rod is when going on off the throttle.  Clutching at straws here!

Cheers,
Jerry

[royhall]

Could this top seal be giving a vacuum leak as it’s damaged

It could possibly, but to my mind that's just a scraper seal to stop crap getting to the inner seal. I may be wrong though, it has been known.