Outboard Compression?

[Guest]

Anyone know what the compression should be in a 2hp evinrude outboard? Im getting about 4 Bar. Its very old and of unknown history, in the last thousand pulls all it has done is cough occationally and once started for 30 seconds then died. I seem to have fuel and spark ok.

 

[andyball]

4 bar? in psi, anything over 100psi will normally start,albeit with difficulty on some engines,sometimes even lower compression figures will run fine.

 

[Guest]

Its about 60 psi, so this could be my problem!

 

[david_bagshaw]

you could try the old trick of some thick oil down the cyl wall to boost the seal, if the engine has not run for ages.

good luck

David

 

[andyball]

60 psi is rather low,even for a cold engine.....the oil trick often works....gets 'em going,then the pressure often stays up after it's been run a while.

 

[andy_wilson]

Forget Outboard Compression?

There won't be many 2 hp motors that have actually been worn out. Stale fuel mix is the most likely problem, followed by gummed up carb, then sticking rings.

Buy a tin of Redex (or even better, if more expensive, OMC 'Tune-up' additive) and apply liberally in the spark plug hole to soak into the piston rings, and into the carburetor to soak into the jets (most OMC motors have a slow running jet adjustment to get clean smooth running at trolling speed, if yours has a knob on the cover with a symbol like a volume control, pull it off, and squirt your choosen liquid in there).

Clean and set spark plug before replacing.

Dump the old fuel and replace with fresh mix, 50:1 if it's an old engine, and use OMC or Quicksilver two-stroke oil. This is the key to success - you could try the fresh fuel approach and forget the rest, it'll probably work.

Open throttle wide and full choke, and pull 20 times to blow the remaining old fuel through.

Set fast idle and close choke, keep pulling to dissipate flooding. At some point it will fire, start juggling choke and throttle to keep it running and warm up.

Set fast idle and adjust trolling control for smooth running.

Re-apply 'tune-up additive' to warm engine to clean up the innards some more.