Help: Yamaha 40hp Hiccup

[Koondog]

I have a Yamaha 40hp (Mid-80's Yamaha 40ESG, 3 cyl, two-stroke) that has a hiccup at idle or when thottling it down to idle. I have messed with the mixture screws and I've tried adjusted the idle timing up and down. The only mods have been a shaved head and removing the oil injection. There are no leaks from gaskets or cracks. Plugs have looked good. I'm baffled. Any ideas? Thanks in advance.

[Fastjeff57]

Are you sure the idle adjustments are rich enough? Sounds like a common 'sneeze' to me.

Jeff

[Koondog]

Are you sure the idle adjustments are rich enough? Sounds like a common 'sneeze' to me.

Jeff

Thanks, I will try going a little richer or increase the idle jet size

[Fast Fred]

a hicup most times is cuzz the throttle plates are not in sinc, check sinc and link adjustment