I checked the compression and...

[3car]

I looked at this little boat today, and it seemed like a good deal. it is powered by a 40 horse evinrude(about an 85' model), and seems to run decent.
I did a compression check, and the bottom cylinder read about 150 psi, and the top cylinder was about 125 psi.

I guess a decarb may help even out the numbers, but what do you think, too much varience? The price is right on this boat, and I'd hare to pass it up but I dont want to replace the motor anytime soon either.

 

[Gary H NC]

Re: I checked the compression and...

Did you check it with both plugs out,throttle opened and engine warm?
First time i did a check on mine the engine was cold.I got low readings and one side was lower than the other.
Did it with the engine warm and big difference,evened them out a lot and much higher numbers.

 

[HighTrim]

Re: I checked the compression and...

Im sure a decarb would even it out even more. Compliments of TD. I think i would invest in a can of seafoam, in a portable tank, mix 3/4 gallons of premix gas, an 3/4 can of seafoam, (assuming you don't have the vro connected). Put the remaining seafoam in a spray bottle, run the motor up to temperture, remove the plugs, one at a time, spray some seafoam into each cylinder and replace plug. let sit 15 minutes, remove the air silencer from the carb while waiting, restart motor, and spray seafoam into each carb, until it start to stall. repeat till seafoam is gone. run out the rest of the gas. it is going to smoke like it is on fire, and drip goo on the ground. replace the plugs with new ones, and then do the compression check again. this procedure burns the carbon out of the motor and been known to free up rings, and increase compression. let me know the results.

 

[jtexas]

Re: I checked the compression and...

don't base a used boat purchase decision on the assumption that a decarb will fix a compression problem.

btw, seafoam comes in an aerosol can, it's called "deep creep"

 

[3car]

Re: I checked the compression and...

Did you check it with both plugs out,throttle opened and engine warm?
First time i did a check on mine the engine was cold.I got low readings and one side was lower than the other.
Did it with the engine warm and big difference,evened them out a lot and much higher numbers.

I checked the compression with the engine cold and throttle closed.

 

[evinrude70hp]

Re: I checked the compression and...

next time try it after the engine was running for about 10 mins. give it full throttle and pull both plugs out. thrn do the compresion test and see how your results are.