288 compression ?

[mikemouse]

I checked the comp in my 288xp a little while ago and coldit mesured 125psi. In some other reading I saw 90psi as sign of sickness but did not notice a spec on a correct compression. Any thoughts or ideas as where to look.

 

[mikemouse]

the village idiot is out today and I'm the fill in it seems. Im going to get a new comp. tester tomorrow but am a little confused on how to get an accurate measure, such as check cold, check warm, or both. I assume comp will be higher if i warm the saw then let it set for a minute before taking a reading. My guess is it will be more accurate also.

"admitting ignorance is the first step towards learning" I hope!

 

[tomdcoker]

288 compression

Compression will be lower if the saw is hot. The cylinder expands. 125 pounds compression is low, but most saws will run O. K. Ninety pounds is cut off point for most saws. I had a Stihl TS 350 super with ninety pounds compression that would not run. I put a small amount of oil in the cylinder and it ran great until it burned all the oil out. Tom

 

[joesawer]

125 psi is a low reading, if it is accurate. Because a chainsaw has such small displacement the volume of the hose and compression tester dilutes the compression being read. If your tester has a hose with a one way valve, the valve should be as close to the cylinder as possible, then several compression pulses will fill the volume above the valve and give a fairly accurate reading.

 

[blis]

Compression will be lower if the saw is hot. The cylinder expands. 125 pounds compression is low, but most saws will run O. K. Ninety pounds is cut off point for most saws. I had a Stihl TS 350 super with ninety pounds compression that would not run. I put a small amount of oil in the cylinder and it ran great until it burned all the oil out. Tom

actually, compression should be higher when warm becouse the rings expand and seal better...

 

[taplinhill]

actually, compression should be higher when warm becouse the rings expand and seal better...

+1

 

[romeo]

As the standard goes, 110 lbs cold is the minimum. They can run with less but will be junk soon enough. 125 lbs can last for quite a while if it has to.

 

[Turbocaster]

U.S. General Compression Tester

I just bought a compression tester at Harbor Freight yesterday. It's only $6 on sale. so the price is very good. I tested it on my 044 Stihl and came up with 122 pounds with the engine cold. My buddy has an expensive tester and his showed 125 pounds on my 044. To be within 3 pounds is close enough for me.

The U.S. General tester works with 14 and 18 mm spark plug holes.

Jon

 

[mikemouse]

Thanks for all the input. Idid not get the chance to recheck with a new gauge yet but tomorrow I will. I agree with blis on sealing better when at or close to operating temps. I am going to check my 266 also. My dad fell trees part time with it from about 96 or 97 until jan. 07, but his boss and him were careful and did better than average maintnance. I'm really just looking for an excuse to overhaul a saw. Making Old Reliable new again is always good feeling.


Making sure the gauge is full is a great tip, I will pay closer attention to that .

 

[andrethegiant70]

You and yours have good taste in saws, Mike. Both of them are highly prized by Husky fans.

 

[ChuckinOhio]

I just bought a compression tester at Harbor Freight yesterday. It's only $6 on sale. so the price is very good. I tested it on my 044 Stihl and came up with 122 pounds with the engine cold. My buddy has an expensive tester and his showed 125 pounds on my 044. To be within 3 pounds is close enough for me.


The U.S. General tester works with 14 and 18 mm spark plug holes.

Jon

Got one of those little gems myself, and it works just dandy.

Can't beat the price with a stick !!

Chuck