1974 25hp Johson Outboard

[D.G.]

I Aquired This Motor Last Year. First Trip Out It Was Running Tip Top But Water Pump Wasn't Working. I Didn't Notice This And Overheated The Engine. First Step I Did Was To Remove The Cylinder Head And Replace The Gasket. After Doing So The Top Cylinder Was Getting Some Water Into It. Took Head Off Again And Seen It Was Warped. Now I Have Shaved The Head To Correct This And No More Water Into The Cylinder. Now This Year It Starts Really Well 2nd Pull But I Have No Top End Power. And Can't Seem To Solve Why. I've Cleaned Out The Carb, Checked The Points, Fuel Filter, Good Spark,New Plugs Everything Seems To Be Ok. Can Their Be A Vacuum Leak Somewhere I Can't See That Would Give Me A Lean Condition At High Speed. What is the proper point gap,spark plug gap. and can someone explain to me on how to time the engine. Thanks for any help my family fishing tornament is next week.

 

[tashasdaddy]

Re: 1974 25hp Johson Outboard

have you check your compression? do you have spark both cylinders? may be more damage from the overheat.

please loose the caps, hard to read.

 

[D.G.]

Re: 1974 25hp Johson Outboard

yes i have spark in both cylinders,i'm checking the compression this afternoon. what should it be

 

[tashasdaddy]

Re: 1974 25hp Johson Outboard

i hope over 100psi, and withing 10% of each other.

 

[F_R]

Re: 1974 25hp Johson Outboard

On an engine that has been overheated, the exhaust cover gaskets must be replaced or there is danger of squirting water into the cylinders through the exhaust ports, causing even more damage. That procedure also gives you a chance to see the piston skirts and rings on the hot side. You aren't going to like what you see. Probably why you are having problems with it.

 

[D.G.]

Re: 1974 25hp Johson Outboard

i lose power when i go over a wake from another boat. when things settle it seems to go back to what i had. i never seem to get any rpm from it. pumping the tank ball doesn't make any difference either. i read on another thread that the point gap should be 20 thou is that right?

 

[D.G.]

Re: 1974 25hp Johson Outboard

sorry i didn't mention that in my original thread but i suspected that and have replaced the exhaust gaskets allready. their was a bit of scoring but i've seen worse. see the last time i tried the engine last year it was running great with lots of power but the head warpage was to much and let water get into the top cylinder and i droped that cylinder. i parked the motor for the winter at that point and knew that i had to solve the head warpage. and i did that and have had it running it running several times this year with no water coming in that cylinder so thats solved but now i've lost my power and can't figure out why.

 

[D.G.]

Re: 1974 25hp Johson Outboard

well i have 115psi compression in both cylinders. i was happy to see that. the points were set at about 10 thou. adjusted them to 20 thou and i'm going fishing to check it out. i'll keep you posted.

 

[D.G.]

Re: 1974 25hp Johson Outboard

so i went out fishing but my engine ran worse i guess the gap is to much i will have to re-adjust that. did notice tonight that after driving for a while WOT that i eventualy would lose speed(power). i would pump ball and it would get it's speed back but the ball never gets hard no mater how much i pump it. could my problem be my fuel pump?? my float was fine when i checked it.