compression test help

[ftm]

Yeah, I can see that a little if the rings are bad. On a 4stroke you take a test and if it is low you put a little oil in the cylinder and test again . If it raises you know the rings are the problem.

 

[lovetheoutdoors]

Raisedbywolves.....how much lower will the compression be if the engine is cold? Are you talking a big diffrence or small diffrence?

 

[RaisedByWolves]

The comp will be higher when the saws cold.

On my SXL-925 cold Ill get about 225-235 psi depending on how long its been sitting and the ambient temp.


After a brief run to bring it near operating temp (not hot) its about 190.


I use this as an example due to the fact that this saw is in the best condition of all of the older saws that Ive done tests on.


The better condition the saws in the bigger the difference.

 

[Lakeside53]

hmmm... I see less than 10psi difference between cold and hot.... sometimes only 5... Must be the 50:1 stihl mix. Most of the saws I see are 175 new'ish, 145-155 average for most of mid-life.

Raised: You still running 16:1 SAE30?

 

[RaisedByWolves]

Plastic tanks, plastic handles, plastic starters, plastic pistons, plastic rings.


What do you really espect when the only steel in the saw is in the name.


Besides if you would simply learn to do the test right.......:biggrinbounce2:

 

[Lakeside53]

Plastic tanks, plastic handles, plastic starters, plastic pistons, plastic rings.


What do you really espect when the only steel in the saw is in the name.


Besides if you would simply learn to do the test right.......:biggrinbounce2:

Hey, my mufflers rust!

 

[RaisedByWolves]

All that work I just did and you were funnin with me? Oh well, I did the work, I feel like barfin, your seein the pic.


50deg F, saw last run on 2:1 90WT hypoid three weeks ago.

 

[lovetheoutdoors]

thanks for the pics and the info.....from now on a will run them a little before i check the compression.....sounds like a winner

 

[Lakeside53]

All that work I just did and you were funnin with me? Oh well, I did the work, I feel like barfin, your seein the pic.


50deg F, saw last run on 2:1 90WT hypoid three weeks ago.

Only 2:1? you too chicken to run it on straight 90?

 

[RaisedByWolves]

Nope, straight 90wt fouls the flint.