1975 Evinrude 25HP Misfire?

[tombold]

Hi, <br /><br />I have a 1975 25hp Evinrude that I for the life of me cannot figure whats wrong. My motor starts perfect, idles perfect (in neutral and in gear), and runs like a raped ape, but on plane either at full throttle or slightly under, (still on plane though) I am getting a misfire or so I think about every 10 seconds or so. It doesn't kill the motor or bog it down, it keeps on truckin, and it doesn't do it all the time, only when its at normal operating temp and even then it still will do it for a while and then it will stop for a while. I took it in and had it looked at and all ignition, fuel system, all checked out. Also had the carb rebuilt. It will not miss in neutral at full throttle, half throttle etc., I am totally baffeled. Would spark plugs have something to do with it, wrong plug, stripped plug threads, I haven't checked that yet, wanted to see if anyone could shed some light before I dig into anything else. Thanks!!!

 

[JB]

Re: 1975 Evinrude 25HP Misfire?

Howdy, Tommy.<br /><br />Sounds like your engine is just a bit rich at top end.<br /><br />This could be a float level a bit high, but I suspect that you simply need to give your high speed mixture screw about 1/4 turn CW.<br /><br />Good luck.

 

[tombold]

Re: 1975 Evinrude 25HP Misfire?

Thanks for the reply. I have been reading other posts and I am getting a feeling that it could be the clutch dog starting to go. Being that the motor runs so good. The motor doesn't pop out of gear at all, after it happens it recovers so well so I am not sure. It seems to happen more when the weather is really cold also. Could this sheld a little more light on the subject. I will try your advice, Thanks!!