View Full Version : low compression ?

10-22-2009, 03:00 AM
What does that mean when the trimmer has LOW COMPRESSION 80 PSI?

What caused this?
When do you have to check for it and how often?
What do you have to do to fix it?
What is normal ? PSI for a trimmer (STIHL fs85R ?:weightlifter:

10-22-2009, 08:11 AM
110 psi on my one low compression can be rings cylinder but at 80 psi it should still sputter and try to start drip a small amount of 2 stroke oil in the plug hole then retest the commpression if it gos up then you need new rings

hope this helps


10-22-2009, 12:38 PM
We dont mess with 2 cycles with less than 100psi. Normal for your machine would probably be in the 130-150 range or higher.

Proper fix would be a rebuild...new piston/cylinder.

Pull your muffler off and look inside. You will probably see alot of lines in the piston and cylinder going up/down.

10-22-2009, 05:50 PM
Try rings first......$10 versus a big load of money for a head.