Inconsistent float/fuel level

[texaschris]

Hey y'all,

I think I've got an issue with my carb float/needle/seat etc. I wonder if anyone had come across this?

Sometimes, the fuel level in the float bowl increases, not enough for fuel to leak out of over flows, but enough to effect proformance because the mixtures too rich. Sometimes it will stay where it should and it runs fine

Needle is new, floats float, and i even gave the seat a bit of a polish.

anyone got any ideas/ possible casues of this for me to check out?? I have a theory that debris from the tank could be temporarily stopping the needle from fully seating causing extra fuel in the float bowl? However, i have added an inline fuel filter, so it would have to be real tiny pieces getting through.

What do y'all think?

p.s. I didnt mention that the carb is from a CB250rs on purpose as advice based on experience around this issue from any bike could be benificial.

Thanks guys,
Chris

[mattday]

The levels on my 32 year old Keihin carbs were pretty hard to get right. I also put in new needles and gave the seat a bit of a polish at first.

However, what I think eventually did the trick, was putting a cotton bud (q-tip) soaked in metal polish in a cordless drill. I used that to really polish the seats and repeated a couple of times. Best if you can get the pointy cotton buds for this and of course clean it out well with carb cleaner and compressed air afterwards.

Also worth double checking that there is no possibility the float pivot could be catching due to roughness somewhere.

[Robby]

If the carb is overfilling, the needle valve isn't closing. Either the float is sticking, dirt is getting it, or the needle/seat is worn.

If it isn't overflowing, then I doubt that the float is sticking.

You've fitted an inline filter, assuming you cleaned the float bowl out afterwards we can eliminate dirt getting in.

So that leaves a worn needle/seat. It's a service item, replace it.