Having a problem with idle on a Yamaha 225 4 stroke. When started it idles fine. After warming up, the idle drops and if I don't keep reving, it stalls. Any ideas on what is causing this?

BC

 

Are you using the choke to start it?

 

Usually, if it starts and runs fine, cold, and the problems happen after its warmed up...its probably too rich. Check the mixture screw, it may be too rich, or the float level may be too high, or the choke may be sticking partially on.

 

Also want to check your valve adjustment. As the engine heats up the exhaust valve especially will expand a bit and maybe beyond the recommended valve lash setting.