98 9.9 Carb Adjustment

[a_jester65]

I recently cleaned my carb and cleaned all of the gaskets. Now I am trying to get my mixture just right. My question is "should I back out engine idle adjustment screw before adjusting the slow speed mixture adjustment?" Also, what is the differenct between the two screws? Thanks in advance.

-Aaron

 

[oldman570]

Re: 98 9.9 Carb Adjustment

Engine idle mixture screw is on the carb and is for setting the fuel mixture with the engine in fwd. gear and the motor warmed up. You should start with it open 1 1/2 turns off lightly seated. The slow speed adjustment is for setting the motor to run 650 to 700 RPM in fwd. gear and has nothing to do with the fuel mixture. It should be located on the throtal linkage.
Oldman570

 

[a_jester65]

Re: 98 9.9 Carb Adjustment

Thanks for your reply. After looking at your reply I have a better understanding. The only difference is I believe the slow speed mixture screw (located at the 12 oclock position on the carb) is for the mixture. The Engine idle speed screw (located on the throttle linkage) is to ensure the engine idles at the rpm you specified.

If I back the engine idle screw out, I should be able to adjust the slow speed mixture screw so the engine stays on. Is this correct?

 

[oldman570]

Re: 98 9.9 Carb Adjustment

Yes that is correct. You might have to screw it in to keep the motor running at first while getting the idle mix set . Then back the engine idle screw out till you get the correct RPM.
Oldman570

 

[a_jester65]

Re: 98 9.9 Carb Adjustment

Thank you Sir

 

[a_jester65]

Re: 98 9.9 Carb Adjustment

Ok, one more question. What is the best way to check the rpm?

- Aaron

 

[a_jester65]

Re: 98 9.9 Carb Adjustment

Any help on that last ???

 

[oldman570]

Re: 98 9.9 Carb Adjustment

Small digital tacks can be bought on Ebay for less than $20 and will work for setting RPM of the motor.