Off topic carb problem...

[Truckedup]

A lot of these mikunis employ an external and internal vent to atmosphere. The external is a passage way from an opening in the air horn to above the float chamber. The internal is a balance tube that equalizes the pressure of the air coming in thru the filter and the pressure in the bowl. Without it the bowl pressure could be higher that the air entering through the filter if really dirty for instance. This would cause a rich condition. With either one blocked, these interconnected passageways can pass fuel.

Sometimes the little air passages in the air side of the carb inlet (that feed air to the pilot circuit) can be clogged, and will cause exactly what you're describing. use a very tiny copper or brass wire to make sure they are clean.

There a large vent in the airhorn to the area above the CV diaphragm and another more typical bowl vent on the side with a tube leading to the highest part of the frame..Being an ATV, some attempt has been made seal off the carb because of water/dirt/mud...There is a small air bleed in the lower airhorn, I will check it out..

I thought I had it fixed, rode the ATV down the road a few miles (rural area) and it was fine. But on the way back it acted up again. It's much worse when warmed up...The "choke" is a separate fuel circuit and I believe it may be leaking fuel...I ordered a few parts...

[Roundybout]

The choke circuit is a definite possibility. You're right it is a separate system. I believe it has it's own fuel jet and the plunger opens that passage. One or two small o-rings is all that seals that plunger thing. Does the mixture screw have any effect when its warmed up? If the choke system is leaking a little fuel into the mix you should be able to almost lightly seat the mixture screw and it will still run.

[Truckedup]

The choke circuit is a definite possibility. You're right it is a separate system. I believe it has it's own fuel jet and the plunger opens that passage. One or two small o-rings is all that seals that plunger thing. Does the mixture screw have any effect when its warmed up? If the choke system is leaking a little fuel into the mix you should be able to almost lightly seat the mixture screw and it will still run.

The choke has a "plunger" that when in operation uncovers a small port that has it's own fuel jet.The plunger movement also uncovers a passage allowing air to bleed in to increase the idle speed and mix with the fuel. There's a small plastic fitting with a tight fitting rubber boot that screws in... . When the engine was idling ,I was poking around with a screwdriver and touched the choke cable conduit ,the engine stalled. I repeated and it stalled again..The plastic retainer is cracked and missing a piece...I ordered the necessary pieces ....
I have Mikuni's on my two race bikes and my street Ducati....The cold starts have metal parts and not a shitty 20 year old brittle plastic nut...

[Truckedup]

Mistake