Mikuni 34mm flat slide on 420cc - dies when warm

[frostyflammable]

I think I know which way I have to go but figured I would ask see what the internet thinks. Basically I have a Predator 420 with a GP Stage 2 kit (rod, flywheel, cam, etc) and a genuine Mikuni 34mm flat slide carb. The problem I am having is that the engine will start and idle just fine from cold, however when the engine gets up to temp it will die but only when idling. I cam twist the throttle a little and it will stay happily running all day long. Right now I have I think a 30 pilot and I cannot remember what main jet, 220 or so I think. Since the bike idles just fine when cold but dies when warm, should I go up a jet size of two on the pilot jet?

Thanks.

 

[65ShelbyClone]

The mixture gets richer as engine temp increases, so worse running when hot tells me it needs less fuel at idle. Isn't there an idle mixture screw? Probably no need to drop the bowl just for idle mixture.

 

[OPmini]

try this carb jet calculator: https://raggedmoto.com/carburetor-jet-size-calculator/
If that doesn't work spend 30 minutes playing with your idle screw and air-fuel mix screw.

 

[Budget GoKart]

possibly valve adjustments my mower acts funny because the valves are too tight but wont run if they are to spec