150 psi cold 135psi hot

[liberty]

Why would my compression be higher cold than hot on my Jonsered 2152?

 

[mountain_man]

You've got a leak in pressure perhaps caused by warped cylinder or something more simple... Piston ring blow-by. Time to check all your bolts first and check them when cold first then warm her up and test hot. I hope you find something.

 

[blsnelling]

That's the way ALL of my saws are. Even with a new OEM P&C.

 

[kurtty]

all my saws read a little lower when hot too.
even the 372xpw which only has 5L of mix through it.

 

[Zodiac45]

Yep same here, all my saws read higher cold than hot too. I don't think I'd worry about it. Hard to make it make sense but maybe dissimilar metals expansion? , blah blah blah......:monkey:

 

[liberty]

Is 135psi a good number. I bought a used saw and want to make sure

 

[mountain_man]

It's more the number difference? Do all your saws read that low when hot? That's about the only concern to it. The 150 cold is a pretty darn good number. So if everyone's drops 15 points then you're clear but I know mine has only about 5 points difference.

 

[wood4heat]

Could be the dense cold air is less compressible and gives you the higher reading. Once your saw is hot it heats the incoming charge and you lose some pressure.

 

[liberty]

I ran a test on my 372xpw that has about 6 tanks through it. 148 cold and 135 hot.

 

[Freakingstang]

It's more the number difference? Do all your saws read that low when hot? That's about the only concern to it. The 150 cold is a pretty darn good number. So if everyone's drops 15 points then you're clear but I know mine has only about 5 points difference.

150 is ok for a used saw. 165-170 cold are much better readings.

 

[Zodiac45]

Could be the dense cold air is less compressible and gives you the higher reading. Once your saw is hot it heats the incoming charge and you lose some pressure.

Interesting thought Wood,

Makes as much sense as anything else.

 

[blsnelling]

Sounds perfectly normal to me. I'd run it.

 

[liberty]

quote:150 is ok for a used saw. 165-170 cold are much better readings


Why then is my new 372 148 cold. It should be broken in with six tanks

 

[trimmmed]

quote:150 is ok for a used saw. 165-170 cold are much better readings


Why then is my new 372 148 cold. It should be broken in with six tanks

Probably not broken in yet with 6 tanks.

I think your compression #'s are good based on the way they compare to the 372's #'s. Don't worry whether or not your compression numbers are matching steve's exactly, unless you are both testing at the same time with the same gauge.

 

[HUSKYMAN]

Will you stop worrying about numbers on a stupid gauge? Go out and cut some wood

 

[kurtty]

quote:150 is ok for a used saw. 165-170 cold are much better readings


Why then is my new 372 148 cold. It should be broken in with six tanks

i got the exact same saw with only 5L of mix through it. its got the same copression as you.

 

[liberty]

Numbers aren't so stupid when you need to leave feedback on a saw. It is nice to know if you got a good saw.

 

[Nitro-Fish]

Numbers aren't so stupid when you need to leave feedback on a saw. It is nice to know if you got a good saw.

Clean it (if necessary), fill it with fresh gas mix & bar oil, start it, adjust the carb for your location (again, if necessary), check to see that the oiler works, the clutch is in good shape, run it through the rpm range, shut it off, see if it starts easily the second time (or third, fourth....... so on if you like), make sure the bar & chain are in good shape, sink it in a few logs, if it does what you expected, it's a good saw!

 

[HUSKYMAN]

Numbers aren't so stupid when you need to leave feedback on a saw. It is nice to know if you got a good saw.

OK you are good then. My point is your p/c are good, go enjoy the thing.