1973 evinrude 25hp wont idle

[brsoo]

Ok. So I started looking at other motors and wanting to give up. I've been torn on what to do. A lot of time and work invested... And am I just being paranoid and over thinking?
My real concern is to have a dependable motor. And it seems like 2 strokes you need to know your motor inside and out.. I don't have time to tinker non stop

Tonight I've been reading about my symptoms. I found something on leroys ramblings about the unburnt fuel in omc 9.9. I think this is my issue? I think my motor has ran ethanol fuel long enough to clog up the exhaust and engine and maybe I should try a seafoam dunk?
I'm currently running a splash of supertech seafoam generic. Is this bad? Good? Useful?
I'm mixing 50:1supertech tw3, should I adjust this?use Pennzoil as people recommend??
I'm running j6c, since I have j8c should I run these for a while to help burn excess mixture??


I am looking to do seafoam and oil in a small amount of gas. Turning motor off for 15 min then running gas out.
As well as changing back to j8c

If I don't have the best spark I can't see how the plugs would damage it. Keep in mind I have a extra power head already haha!

Am I on the right track?
Could this still be related to a fuel pump, head gasket, or thermostat?

 

[hardwater fisherman]

If you look at the evinrude website they call for UJ4J spark plugs for your motor. Which are NLA. I have been told here that these lo tension magnetos can and do foul spark plugs. I have experienced this with mine. After rebuilding the carb and replacing the points I fouled 2 sets of champion plugs trying to get the carb set. I fouled a third set of champions while trolling. I also read somewhere, maybe Leeroys ramblings that these motors may run better and foul the plugs less with NGK plugs. I use NGK B7HS and have had gook luck. If you want to try the NGK it appears the UJ4J is NGK B7S. For the no start issue I would lightly seat the low speed needle and then turn it out about 1 1/4 turns and if every thing else is ok than it should start and then work your way in with the needle. If you get it dialed in to where it is running well then the exhaust residue should clear up. A good WOT run will help. IMO the exhaust goop you are seeing is a result of a poor running motor and not the cause of the motor running poorly. Or maybe if you have spent alot of time running in a barrel then it could have been a build up that needs to be run to clear it out.

 

[brsoo]

No Title

Ok guys. I read up on the issue a LOT, leroys had a long post on 9.9 trolling with lo tension magnetos. Also read and watched videos elsewhere on plugs and their behavior. So far I've found two very good sources and solutions. 1. All my sources suggest for good high rpm gap lower, at low rpm gap wider. This will give better trolling and idle. 2. Use a marker and mark where the electrode is on plug. Try to orientate the electrode to face the intake so that its less likely to foul. So last night I cleaned and re gapped my j8c plugs to .40.... Then it hit me! If my points wanted to be gapped at .25 instead of .20, maybe my checker is not accurate. Or maybe I suck at using it haha I then drew a little line in it and found my best position. And it started strong with a cloud of smoke. I had to run the needle down leaner then I ever have before... I think I'm getting a better fire inside now.. I did find a little bit of water in my lower cylinder.. Like little bubbles floating on the gas mix. There was one on the plug hole. Is this my head gasket? Where would water mix in the fuel? I have another power head. So I'm going to run it anyways just to see how it runs. After re-checking for water I may tear it down.

 

[brsoo]

Well.....
It started first pull and I let it warm up a bit. Adjusted the carbs for a bit. And it idled really good. Started it back up then it just acted up again. Nothing put it back to normal. Still oozing crap all over.
I pulled the plugs. The bottom one was clean and had water on it. It really showed signs of water this time.
I'm very much thinking it is a gasket at this point. Once again I'd assume its the head gasket. Is there another it might be??

Please let me know before I tear into it. I'd like to think I'm not wasting my time doing this...
Thanks

 

[wauto]

Exhaust cover gasket will allow water in also.

 

[brsoo]

With as perfect of compression that I have if assume its that. Doesn't a power head gasket change your compression?
The actual "head gasket" has nothing to do with water intrusion right??
If I had an idea what to change ill likely tear it down and replace all of it. And if the power head is cracked or scored I will replace with my other one.

Just searching for some advice. I've been reading all the info I can find. I'm seeing mixed things and I'm currently moving to a new place. I need to focus elsewhere....

Thanks y'all

 

[AlTn]

pull the power head and disassemble for inspection...I have a '71 25 hp. that had 120 psi on each cylinder as well, however the top cylinder that a broken top ring that the second ring was compensating for compression wise...this motor had idle issues as well, one day all was well, the next day wouldn't idle and would die coming down from wot in a sudden snap..this is the only way you'll know for sure what's going on..yeah, first time pulling the power head is a little challenging, but by the third time you'll have it off no time on this series of engines