Re: 1965 Evinrude Lightwin – Speed Question

[Casey Lynn]

Couple things that have not been mentioned.
Since the idle needle does not appear stock the needle may have been replaced due to grooving of the old needle.
Have found, for the most part, that once a needle has been grooved that the seat is pretty well deformed as well.
Usually when the idle needle seat is deformed a new needle or one that has been turned down will be marginally better but
still difficult to hold a good setting. The setting will drift and require fairly constant adjustment. Is this one of your symptoms?
The engine sounds pretty ratty at idle and is hard to start without choke and plenty of spark. This is why I would suggest the basics (compression, etc.) The engine may have been overheated to the point where pistons were damaged and/or rings are stuck.
Someone HAS asked if the engine is pumping water haven’t they? You DO know where to check? Not going back through three pages to find out.
If stuck mechanically (by piston debris) then Seafoam or whatever magic potion you throw in there will never work. If just stuck badly with carbon the idle will still be affected but you have a chance of cleaning it up.
Would suggest you stop using the little league stuff and go to OMC Engine Tuner or Mercury Power Tune. This is the real deal when it comes to de-carboning. Read the directions and let it sit overnight. Any less and you aren’t doing the engine a favor.
After checking compression you can pull a side cover and see what shape the rings are in. Let us know.
Now…..back to your regularly scheduled troubleshooting.