The correct kind of compression guage

[briantutt]

At the risk of sounding like an idiot....

Are compression testers just a gauge with check valve on the inlet to trap pressure? and an outlet valve to vent it off when done?

and if these are just bourdon tube gauges you can't expect better than 3% plus or minus and usually 5% plus or minus for accuracy and that is full scale range so if it's a 300 psig gauge it could be off as much as 15 psig for any reading and still pass the spec at the manufacturer. I spec this type of gauge in all the time and at the prices they sell these testers for there is no way they are better than 3% and are more than likely th 5% variety. In any case they should repeat the reading so if you figure out it's 5 psig off from a calibrated reading it should stay 5 psig off unless it's abused.

 

[deezle_dog]

At the risk of sounding like an idiot....

Are compression testers just a gauge with check valve on the inlet to trap pressure? and an outlet valve to vent it off when done?

That is correct.

 

[stihlbro]

Reading here and thought I would add my two cents here. I have a snap-on compression tester and two others that where alot cheaper. All three read really close to each other. But my thoughts on comression here is it only makes you scratch your head and stay up at night. Checking compression on a stock saw for reference the guages are helpful. Most of the time you can tell if compresion is good by the pull of the starter rope. To me a good cutting saw the compression is a given. Now........trying to get 200 psi compression on a 026 like everyone else says is so easy......Well let me tell you I personally have failed with every possible scenario possible. With that said I have checked the same saw numerous times cold, hot, sitting for awhile and get different readings everytime. So all in all my opinion of compression readings can be misleading. Altitude? Ambient temperature? Hot? Cold? Your guage? My guage? I will agree with 046 on calibrating a guage for accuracy. And you must have a schrader valve....sometimes a valve stem valve will work. Keep pulling until the guage maxes out. Hopefully I am not the only one experiencing this.

 

[Jtheo]

I'm going to ask Greg to chime in here. I've never seen the tester Baileys sells but am told that it does no have the required valve at the tip. Maybe Greg can clarify this for us. They're always looking to improve their product so it's only fair for him to know what the end users are experiencing.

I bought the compression tester from Bailey's and it does Not have the Schrader valve at the tip.

 

[Haywire Haywood]

When did you buy it? If recently, it doesn't look like a typical schrader valve, just looks like a brass blockage up in there.

Ian

 

[blsnelling]

You are correct that it does not have a "Schrader" valve. However, it does hava a one way valve right at the tip of the hose. It will work fine.

 

[Jtheo]

When did you buy it? If recently, it doesn't look like a typical schrader valve, just looks like a brass blockage up in there.

Ian

I bought it last summer. I looked in the end of the connecting hose and it looks just like you said.

So this should do the job. Right?

Thing is, I just ordered one from AutoZone a little while ago, so I guess I can compare the two. If I can find out out to do the test properly. :greenchainsaw:

 

[blsnelling]

I don't know when they made the switch. What kind of compression readings do you get from it? If it's reading 140-160 PSI, it has a valve at the tip. Otherwise, your readings would be much lower.

 

[derekc]

Back to how dry the inside should be for accurate test.

Back to how dry the inside should be for accurate test.
100% dry and well-lubricated with 2-stroke oil on the rings make a big difference.
I just put together a 026 with new ring, piston and reused the cylinder. 100% dry is 140 PSI. When I squeezed some oil into the plug hole, pull it a few rounds for the oil to go in, then PSI is 180.
So, how dry should it be? Run the saw for 5 minutes first, cool it down, then test again?

 

[husqvarmit]

got mine from echo for 12 dollors and works right everytime

 

[Haywire Haywood]

Back to how dry the inside should be for accurate test.
100% dry and well-lubricated with 2-stroke oil on the rings make a big difference.
I just put together a 026 with new ring, piston and reused the cylinder. 100% dry is 140 PSI. When I squeezed some oil into the plug hole, pull it a few rounds for the oil to go in, then PSI is 180.
So, how dry should it be? Run the saw for 5 minutes first, cool it down, then test again?

Dry... if you want to see the compression go up, squirt a little bar oil in there. Don't ask me how I know this. This also works quite well for mosquito fogging.

Ian

 

[derekc]

I know.
And during the assembling, the rings are supposed to be lubricated before they go into the cylinder. How much lubrication it has will have effect on the compression test result.
Best to test is then after running the saw for say 5 mins and cooling it down?

 

[Haywire Haywood]

I'd say start it and run just until it stops smoking excessively. Shouldn't take but 30 seconds or a minute at most.

Ian

 

[flashpuppy]

I imagine the only tester more accurate than my Mac one might be the Snap-On, that is if they aren't made by the same company!

It's all made in Taiwan. Don't worry. My new Mac sockets I ordered (I was missing two of them from a set) cost me $32 and had a "Made in Taiwan" sticker right on the bag....

 

[7oaks]

My Stihl S-10 has new rings and a good cylinder but still only makes 125 PSI.

Brad...

Just caught this quote and it makes me feel much better as my S-10, 08 and 08s as well as my Contra all register 130 psi on my Lisle guage. My more modern saws all read 150 on the same guage. I was thinking I would have to rebuild the older saws even though the pistons, rings and cylinders all look pretty damn good.

Thanks tons for this observation. I am much relieved. My little bit of rep coming your way.

...Carl

 

[rngrchad]

It's all made in Taiwan. Don't worry. My new Mac sockets I ordered (I was missing two of them from a set) cost me $32 and had a "Made in Taiwan" sticker right on the bag....

Yeh you must have bought the Mac "Edge" sockets. Those I'm thinking are their low-end tools designed to compete with Snap' On's Blue Point stuff. I've wrenched alot with those "edge" sockets by Mac. They seem fine. Nothing special...but seem to work as well as my Flank drive Snap on Sockets...but they are a bit bulkier than my Snap On Flank Drive sockets...anywho on with the thread.

 

[MS260 Fan]

Pulls to get max compression?

Everyone's talking about compression values. Just wondering in your experience how many pulls it usually take to get the compression max out on the schrader style gages. I've seen gains up to the 10th pull on some of my saws.

Also, may be operator error but checked my 034 one day cold and it was 130 and 2 weeks later it was 145. I'll check it again in 2 weeks. I've got my fingers crossed for 155.

 

[blsnelling]

Brad...

Just caught this quote and it makes me feel much better as my S-10, 08 and 08s as well as my Contra all register 130 psi on my Lisle guage. My more modern saws all read 150 on the same guage. I was thinking I would have to rebuild the older saws even though the pistons, rings and cylinders all look pretty damn good.

Thanks tons for this observation. I am much relieved. My little bit of rep coming your way.

...Carl

Glad I could save you the trouble

 

[HittinSteel]

Howdy,
I'm not sure who told you that or why but, ours is on the gauge. The gauge we sell is the same one Husqvarna sells to the dealers. We just access it directly from the manufacturer in Taiwan. We used them for many years without worry. I can't vouch for accuracy because that was the only one we used.

Brad,
If you want to do some comparison testing, I'll send you one.
Regards
Gregg

Gregg, I think some of the confusion (at least on my part) was from the first question under the FAQ section. http://www.baileysonline.com/itemdetail.asp?item=G+320HD&catID=
May want to edit the answer as to describe how this tester works. Would hate to see people shopping based on the word shrader pass the gauge by.

 

[Grande Dog]

Howdy,
Thanks for the heads up. I had it changed.
Regards
Gregg