Evinrude 25hp WOT problems...

[Bruce Hobart]

My 1988, tiller, 2cyl. manual start Evinrude will not reach maximum rpm at wide open throttle unleess the lean/air screw (needle-valve) is turned out 1/4 to 1/2 of a turn out (i.e. from in all the way);unfortunately the motor will not idle at this setting. All adjustments are correct, float setting has been done and carb completely overhauled...yet I can't find a happy medium for WOT or idle. Help guys, I getting desperate...(oh new intake gasket was installed with new carb base gasket..no vacuum leaks that I'm aware of. Thanks ahead of time for your input!

 

[russeller]

Re: Evinrude 25hp WOT problems...

i thought for idle it was 1 1/4 turn out

 

[Bruce Hobart]

Re: Evinrude 25hp WOT problems...

Russ, you're correct and the engine idles fine at that setting (1 1/4 turns out) but it really is hurting at WOT, i.e. it is not reaching the max rpm's unless I turn in the needle valve air/mix setting to 1/2 out...I can actually hear the rpm's increase @ WOT with the shroud off while cruising the boat and motor and leaning out the air mix.

 

[Bruce Hobart]

Re: Evinrude 25hp WOT problems...

Originally posted by Bruce Hobart:<br /> Russ, you're correct and the engine idles fine at that setting (1 1/4 turns out) but it really is hurting at WOT, i.e. it is not reaching the max rpm's unless I turn in the needle valve air/mix setting to 1/2 out...I can actually hear the rpm's increase @ WOT with the shroud off while cruising the boat and motor and leaning out the air mix.

 

[wilde1j]

Re: Evinrude 25hp WOT problems...

Forget # of turns ... adjust idle mix, then HS mix till mix is correct at both power settings. May have to repeat the process a few times to get it right. If you can't tell when the mixture is right, find someone who can.

 

[jim dozier]

Re: Evinrude 25hp WOT problems...

I may be wrong on this because I don't know the exact setup on the Evinrude carb, but I would not think that the idle mixture screw would have any effect on a properly operating engine at WOT. Generally, the main jets take over supplying the fuel for the mixture at just off idle speeds. Something else (I believe) is wrong with this picture.

 

[Bruce Hobart]

Re: Evinrude 25hp WOT problems...

WildeOne: thanks for your input; unfortunately, I cannot find the "happy medium" you are describing, i.e. either the mixture screw is turned in enough for high rpm wot and a stalled idle or if it's turned out more than a half turn, wot is compromised and the motor idles fine; I am waiting 15 secs. with each adjustment so the motor has time to "recalibrate" its mixture. All of these "test and tune" sessions are on the water. Could float level be the culpeit?

 

[jim dozier]

Re: Evinrude 25hp WOT problems...

Does this engine have an adjustable high speed jet in addition to an adjustable low speed jet? If it does you have to go back and forth between the two because changing the high speed mixture will affect the low speed mixture. Get it running right at high speed then fiddle with the idle. If this isn't the case then nevermind.

 

[Bruce Hobart]

Re: Evinrude 25hp WOT problems...

No WildeOne, there is only the adjustment for the idle or "low speed" mixture. Once again, I checked the float level...for correct settings with carb inverted and then right-side up. All measurements are within specs. The right-side up setting is near the maximum of the recommended range (this woulld be the float drop measurement).