bad compression

[racin08]

i have a 1985 eninrude 50hp. finally got it running smooth. was on the lake at WOT and slowly started losing power and then shut off. would crank but not start. engine was very hot to the touch. comp test today showed 45 upper and 115 lower. got it to finally run but is very rough and have to have the idle way up to keep running. also backfires every few seconds. i read about the decarb spray and was wondering were to get it? my other question is were do i start in troubleshooting and correcting my problem(s)? thank you all in advance for any advice.

 

[dakk1]

Re: bad compression

racin08<br /><br />I would pull the head and have a look see.

 

[TELMANMN]

Re: bad compression

45 and 115? Dakk1 has correct answer. Probobly won't like what you see. Get a manual and have fun.

 

[racin08]

Re: bad compression

took head off and was happy to see a blown head gasket. cylinder walls look great even in the bad cylinder. ran on the lake for about 20 minutes. now have compression of 108 upper and 135 lower. should i try decarb to try and get them closer together? thanks for everything guys

 

[roscoe]

Re: bad compression

Yes, do the decarb, it is good medicine for all 2 stroke motors. Spray cans of decarb can be bought auto parts stores, depending on where you are, it may not be a stocked item, but they can get it for you in 1 or 2 days.

 

[tntwalker]

Re: bad compression

You can obtain SeaFoam DeepCreep from Napa Auto Parts... The aerosol can makes it nice and easy to shoot into the carbs... Be ready to make the neighbors mad!!! Don't know that it will bridge that gap, but it won't make things worse.

 

[racin08]

Re: bad compression

again, thanks for all of your help. I got a can of de-carb from west marine today and followed its instructions. now compression is 120 top and 135 lower. i've heard that the rule of thumb is greater than 100 and within 10. will i be ok like this? will it get better with a little bit of regular running? what else can i do? thnx again

 

[dakk1]

Re: bad compression

racin08<br /><br />Yes, sounds like your good to go! The rule of thumb on compression is within 10% and your real close. Go fishin'!

 

[racin08]

Re: bad compression

thanks dakk1. just didn't want another unexpected surprise with my son