Compression for Stihl Engine - What a good reading?

[Jonny Vee]

Does anyone know the compression (PSI) for the stihl engine when they are new condition? Going to view a professional chainsaw which they say does not work and only fuel needed. Sound strange as everyone can put fuel and try. Got compression reading tool and if allowed can try but not sure what would be a good reading. I know everything above 90/100 engine will start but would like to know if is just about to run or engine is still in good health.

Thanks

 

[Burnerman]

It’s a bit of a difficult one, especially with two strokes but you need a minimum of 110 psi.
If the engine has no decompressor it should be impossible ( almost) to drop start it as the compression should cause the machine to jump about......they really need to be trapped by your heel.
One good way to check is to pop the exhaust off and look down the port to see the piston and rings which shouldn’t be scored.
John

 

[Jonny Vee]

Thanks John

Not sure when buying second hand they allow you to do all of these check but will try. If there is compression at least is not the engine packed.

Will let you know

 

[Burnerman]

The fact that the machine ‘doesn’t run but just needs fuel’ rings an alarm bell......
On a different matter, have a look at the machine underside.....if it’s been bouncing on concrete the castings can wear through - seriously!
John

 

[Mr Chibs]

Take a half/litre of pre-mixed fuel with you