1999 Yamaha OX66 Low Idle, Dies

[diver94]

Hi,
I need some advice. Is there anything I can do to adjust the idle speed for a 1999 Yamaha 150 OX66? The engine runs well under load, but idles at 600 RPM, then after 15-20 seconds it goes down to 400 and dies. Sometimes (after it reaches 400 RPMs) it comes back to 600 and keeps running.
Theses engines are fuel injected 2 strokes so I dont know its they have a screw to raise the idle RPM a little.
I used Seafoam to clean the air intakes/carbs but nothing changed.
Thanks,
Lui

 

[th365thli]

I've been going through the exact same thing myself. Two things are checking the full-retard timing and maybe doing a carb rebuild. Don't know if you bought that motor used, but sometimes people mess around and get things out of spec. I recently realized someone screwed up the idle timing on my motor.

The other thing to check, which I haven't done yet, is your low speed jets might be clogged. This requires taking out and disassembling the carbs. Seafoam won't clean those tiny spaces around the jet.

 

[diver94]

I've been going through the exact same thing myself. Two things are checking the full-retard timing and maybe doing a carb rebuild. Don't know if you bought that motor used, but sometimes people mess around and get things out of spec. I recently realized someone screwed up the idle timing on my motor.

The other thing to check, which I haven't done yet, is your low speed jets might be clogged. This requires taking out and disassembling the carbs. Seafoam won't clean those tiny spaces around the jet.

Th365thli
Do you know how to adjust the idle speed a little?. BTW, these engines are fuel injected 2 strokes. I hope theres a screw I could play with a little.
Thanks!
Lui