Mikuni BS34 carburetors rebuild, OVER-SIDE piston.

[Josip08]

Good morning, afternoon or evening,

I have a 1981 xs400 Special II, which I am rebuilding, it has Mikuni BS34 carburetors.

I am installing OVER-SIDE piston stage 4 (factory: 69mm) (over-side: 70mm)

1. Should I rebuild the carburetors to provide more fuel?

2. Should I rebuild the normal carburetors?

3. If I should rebuild to provide more fuel, what should I change, and at what measures.

P.S.: I am not a mechanic, I am only good with my hands and tutorials, if you can provide me with the purchase links in the USA, I would greatly appreciate it in advance.

And greetings from the Dominican Republic.

 

[tstidham]

It's only a 11cc increase in displacement from 392cc to 403cc. It shouldn't really affect the fuel mixture that much. I'd rebuild to stock and see how it runs before trying any jet changes.

 

[Josip08]

Searching for information I saw somewhere that the CC increase was very little, and my logic told me the same thing that you wrote to me, thank you very much.