What should the compression be on a 2 stroke outboard engine?
Two-Stroke engines should have a compression reading of around 110-130 PSI. Sometimes having compression as low as 80 and 90, the engine will still run great!
What is considered low compression on a boat motor?
Generally, readings below 90 PSI for modern two-stroke outboards indicate a problem; most will produce cranking compression readings in the 90 to 105 PSI range, depending on the engine year, make, and model.
What should the compression be on an Evinrude crank?
However if you watch the end my video below you will see that my 1979 Evinrude 6 Hp cranks easily cold ( 2 pulls) with 60 psi compression This source says the older two stroke outboards below 25 Hp should be between 75 and 85 psi. This source seems to confirm with my understanding that 60 psi in older outboards can sometimes be OK.
What should the cylinder compression be on a Mercury outboard?
From my research, cylinder compression values that people say are “acceptable” for low horsepower outboards seem to vary. They not only vary from the reporting individual but from manufacturer to manufacturer. For instance, a fully functional Mercury 25 Hp cylinder compression value may be significantly different than that of a Johnson 25 Hp.
Can a outboard engine run with low compression?
Yes, an outboard will run for a little while with low compression. If the compression is too low though, it will not run at all. Here are all of the things that you need to know about low compression on an outboard engine, what they mean, and how they affect the running of the engine!
What should the cylinder pressure be on an outboard?
Since most of us do not live at sea level, the actual ideal theoretical cylinder pressure should be slightly less than that since the atmospheric press is less at higher elevations. Good working outboards generally have a compression of 75 to 85 psi.
However if you watch the end my video below you will see that my 1979 Evinrude 6 Hp cranks easily cold ( 2 pulls) with 60 psi compression This source says the older two stroke outboards below 25 Hp should be between 75 and 85 psi. This source seems to confirm with my understanding that 60 psi in older outboards can sometimes be OK.
From my research, cylinder compression values that people say are “acceptable” for low horsepower outboards seem to vary. They not only vary from the reporting individual but from manufacturer to manufacturer. For instance, a fully functional Mercury 25 Hp cylinder compression value may be significantly different than that of a Johnson 25 Hp.
Yes, an outboard will run for a little while with low compression. If the compression is too low though, it will not run at all. Here are all of the things that you need to know about low compression on an outboard engine, what they mean, and how they affect the running of the engine!
What should the compression be on a two stroke engine?
For a general number scale for compression. Two-stroke engines should be somewhere between 100-120 PSI per cylinder. Then four-strokes are going to be somewhere between 150-210 PSI! This is where the throttle position comes in.