Flooding Carb problem Solved !!

All the carbs on my 1983 XJ 550 had new seats, needles and were cleaned to within an inch of their lives. #1 carb kept flooding when I was trying to set the static fuel/float level. With help from this forum I finally traced the problem to a slightly undersized o-ring on the needle seat. The seat o-ring was allowing fuel to pass by the outside of the seat and into the float bowl.
These were all NEW seats and needles. Just shows ta go ya, even new parts can cause problems. Maybe somebody can save a lot of time by checking for this problem on their rebuilt carbs.

 

I'm thinking back to my carb rebuild and can't remember an Oring on needle. Where was it exactly?

 

If I recall mine is a washer not an oring but I have heard of leakage around the seats. Good thing to check.

 

It's not on the needle, it's on the seat of Mikuni carburetors. Hitachi carburetors screw in and have a sealing washer as Bill indicated.

 

All of the Mikuni Carbs I have seen with overflowing problems have been related to the o-ring around the seat. They like to shrink up and stop sealing and the gas goes right around the seat.

MN

 

This o-ring?

 

yes there is an oring that goes on the valve body of the needle setup. when installing use lube so the ring is not damaged.
a quick way to tell if yours leaks is to fill carbs and have bowl off hold the float up and see if fuel is passing by the o ring.

oring fits in a groove on the valve body.

 

What's the size of the o-ring?

 

I do not know I just order them from xj4ever.com and he sends you the correct o rings