Compression testing?

[Stihl 041 super]

What is the difference between testing a saw cold and testing it hot?

 

[Kenskip1]

041 Sup,
The reason is thermal dynamics. As metals expand when hot including the block itself, the clearances also expand.As all these factors swell, the clearance also swells. A cold engine may have a compression of saw 125 psi. The same engine Hot, may only have 115 psi.I hope this helps, Ken

 

[Stihl 041 super]

thanks

Thanks . that helps.