How much compression should there be on 1985 Evinrude 70 hp?

How much compression should there be on 1985 Evinrude 70 hp?

Re: Compression #s for 70 hp Minimum to run would be around 100+ anything under that is iffy and the cylinders need to be within 10% of each other no matter what.

What is good compression for 2 stroke outboard?

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!

Is 90 psi a good compression?

They shouldn’t vary more than 10% from highest to lowest. That all said, 90 psi is too low, even for a low compression engine.

Is 110 psi compression bad?

There is more than one school of thought on what the compression, of the average engine should be. As a general rule a compression of 135 PSI or better is excellent. Similarly, a compression of 85 PSI or lower is extremely bad. As long as the lowest reading is 100 PSI or better; then the engine is acceptable.

Is 90 psi a good compression for a 2 stroke outboard?

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.

Is 120 psi good compression on outboard?

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! You will see a good compression reading of 150-160 PSI.

What is normal engine compression?

Healthy engines should have compression over 100 psi per cylinder, with no more than 10 percent variation between the highest and lowest readings. With a compression tester, a few hand tools, and 20 minutes, you can try this yourself.

Will a 2 stroke Start with low compression?

Check Your Piston Rings Since the piston rings’ main job is to create compression in a two-stroke engine, they are usually the cause of a lack of compression. If your engine will start, but won’t hold compression or sputters and dies when you accelerate, there’s probably an issue with your piston rings.

Can you fix an outboard with low compression?

Sometimes you can do things to bring up the compression and fix the issue. You can disassemble the engine and change out bearings, rings, rods, and other components that could have failed. Replacing the head gasket and honing out the cylinders is common.

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 compression be on an outboard?

This source says modern two-stroke outboards should be in the 90 to 105 psi range. 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.

What’s the compression reading on a Johnson Motor?

Some motors were known to be lower compression motor off the bat. Excellent example of what am referring to is the 9.5hp Evinrude/Johnson motor that where built from 1964 to 1973. It is not uncommon to find compression readings ranging from 55 psi to 80psi on these motors. Most of them are in the 60’s and 70psi range and they run fine.

How much psi do you need for compression?

Compression is about 125 psi on each. As far as I have ever known (some may disagree, but I have always followed) once you get below 100 psi your getting border line on whether or not the motor is gonna run much longer. Are you doing it with a pull rope or starter?