35hp Mercury compression problems?

[estay]

I have a 1988 35 HP Mercury, it seems like there should be a decompression system somewhere on the motor, and i was wondering i someone could help me find it. I dont think its working.
I can hardly pullstart the motor over, nor can the battery hardly turn it over.
if i take the plugs out and pull it over it turns fine. can anyone please help me?

 

[will941s]

Re: 35hp Mercury compression problems?

Sounds like you have good compression. The only motors I know of that have a decompression system is the new 4-strokes. I don't know of a 2-stroke that would being that there are no valves to release the compression. The motor really is'nt designed to be pull started on a regular basis, even the 25's are hard to pull start. The starter should turn it well, and if it is'nt then you either need to check / replace the battery, or have the starter tested....it could be going bad and "dragging", therefore it will have a hard time starting the motor.

 

[oldgradywhite]

Re: 35hp Mercury compression problems?

Well come to the mercury 35 a real HIGH Compression motor. I have the same motor and I can't pull it over!

 

[estay]

Re: 35hp Mercury compression problems?

Thing is, i can pull it over and i have many times, but now all of a sudden i cant, it stops between every part of compression. nor can the starter turn it over, because its burnt up now. maybe il try a new starter, but i dont want to burn another one up doing this.

 

[will941s]

Re: 35hp Mercury compression problems?

When you pull the cord and it pulls freely then catches and has alot resistance between rotations of the flywheel is the cylinders compressing the air, then you pull it some more than it releases is the compression going out the exhaust. Nothing wrong with it. If you could pull it freely...then you would need a rebuild. Could be that it had bad compression at one point (maybe stuck rings) then they freed up and you got the compression back. Who knows but it sounds like your good to go. The starter thing, if you run the starter more than 3 seconds it gets hot...then burns up. Use the starter in short bursts with a break in between to let it cool. It's a high compression motor and the starter goes through alot to turn it. Have it tested before you buy a new one. Could the starter going bad, or something else in the starter electrical path. Make sure you have a fully charged battery also. Your motor is fine though. If you really want to check it, get a compression gauge, start the motor and let it get to operating temp. Turn it off and pull the ignition kill cord. Pull all the plugs and test the compression from the top cylinder to the bottom with the throttle in the full open position. Turn it til you get the max reading.