Mikuni Flat-Slide Overflow Problems

[IronSteed357]

Ok, so I know this probably isn't a jetting issue but you guys really know your carbs and I was hoping you could help me out. I just put a new White Brother's 34mm Mikuni Flat-Slide Carb on my '91 DR350S. After some tweeking I got it running smooth except that it dumps fuel out the overflow hose whenever it is running. I totally cleaned the carb, checked that the floats were free-moving, made sure the needle valve was closing and that all jets were clear. The carb doesn't leak a drop of fuel when its just sitting there but I soon as it starts running, a fairly constant stream of gas pours out the overflow. Anyone out there got any ideas about what's going on and how I can fix it?

[Maniak]

I would make sure that your float needle and seat were clear of all debris and then check again, just a little bit of lint can let the gas bypass the seat, but also make sure your float height is set to factory spec, even brand new carbs need to have the float height checked.

[punkrock MX]

mine did the same thing

find a kehin!!!

[IronSteed357]

Ok, so I adjusted my float and stopped the overflow a idle. However at about 5500 - 6500 RPM the gas started running pretty steady out the overflow. I adjusted the float again and same problem. Adjusted it one more time and the float wasn't allowing enough gas in the bowl to do much more than idle for ten seconds or so before starving the engine. I've been working on this for two weeks and can't think of anything else. Any more suggestions?

[Wayward Son]

the needle and seat are worn.

[IronSteed357]

I don't think it is the needle and seat. This is a practically new carb and when I flip it upside down (so the floats are closing the needle) I can't blow any air through the fuel line.

Anyone want to make a guess why it only overflows at higher RPMs?