Yamaha 1988 130HP Idle Mixture Screw Settings

[fsutim]

I began rebuilding my Carburetors this weekend and got ahead of myself and took out the idle mixture screws for one set of my carburetors. The problem was I didn't mark where the screws were before they were unscrewed. Any insight as to how these screws are supposed to be seated? I installed the carbs back on the engine and its running on high RPMs but will stall when you try to idle. I have attached an illustrated picture of the idle mixture screws that were removed in figure A of the attached picture. Could someone please help me with getting these screws adjusted.
Thanks!

- Tim

 

[cousinabe]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

Tune up Guide says 7/8 turn and timing at -5 degrees (5 ATDC)

 

[fsutim]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

Could you please describe what "7/8 turn" means?

Thanks!

 

[cousinabe]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

turn the screw in all the way till it lightly seats. then turn out 7/8 turn.
8/8 would be a full turn out... so a little less than 1 full turn out from seated.

 

[fsutim]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

Thanks for the clarification. Just to confirm, Is it lightly seated when I first start feeling resistance while turning the screw? The reason why I ask is there is a spring on the end of the screw and I imagine I could get about 5 complete turns after I start to feel the resistance that the spring causes.

 

[cousinabe]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

no. lightly seated means all the way in till you can't turn no more... past the five turns of the spring engagement.

 

[douglloyd]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

The trick is not to scar the brass adjusting screw or the seat. You don't want to gaul the needle, if it is already by visual inspection get new or it will never be right.

 

[fsutim]

Re: Yamaha 1988 130HP Idle Mixture Screw Settings

Perfect, Thanks for all the help. Hopefully I will get this engine purring again.