Hey guys
I have a used 250 that has me stumped. when you first start it with the choke off it will not idle unless you give it just a little throtttle. You can keep it running doing this and start turning in the idle screw to the correct rpm. Then if you touch the throttle or sometimes if you don't the rpm's will go to about 2000-3000 on there own if you pop the throttle open to close it may settle back then take off again. It does this when the engine is hot or cold. The motor does smoke a little after sitting overnight right after you start it.
Any ideas sure would be appreciated????? Thanks in Advance
TBS

 

When the rpm's increase just sitting there is it leaning itself out. So it is not getting enough fuel. I would check your vent tubes for obstructions and clean the carb. Especially check the float bowl for gunk and the needle jets.

Then adjust the idle screw and see if it changes things.

Swampy

 

yeah, sounds like a clogged carb or stuck choke. tear it down and clean it and make sure you get everything back together correctly. check choke linkage and throttle linkage to make sure everything moves like it should, then try it again.

 

my 300 does the same thing i found a restricter in a vent tube that goes toair casing is that should be there