Stihl 261 Compression

[H 2 H]

When I tested mine I was at about 25' elavation about 1/2 mile from Puget Sound

I'm going have it tested I hope this week from and engine shop to see the difference between my gauge and their's since they are in the business of making sprint car engines and there proablly about 50' elavation

 

[blsnelling]

one last time for those of us who cannot see/read past the end of our nose.......

:chatter::msp_flapper:

 

[MEATSAW]

Well the piston/cylinder checked out, and it runs as good as new. I had him redo the compression and it was at 155psi on the 2nd test. This one is a tough decision.

 

[Andyshine77]

Call me silly, but every saw in the same model I've tested had different compression, and sometimes the variance is quite large, same with P&C quality, combustion chamber size, squish gap you name it. There is no set number within reason. My .02

 

[STIHLTHEDEERE]

Well the piston/cylinder checked out, and it runs as good as new. I had him redo the compression and it was at 155psi on the 2nd test. This one is a tough decision.

there is not thing wrong with that saw, just as suspected. but NONE of us had know real way of knowing for sure. i would not be afraid of it at all, they really are great saws, and you will love it.

 

[MCW]

My MS261 was 160psi when I sold it and my standard Huskies tend to hang around 150-155psi. This is within spec according to most information sources. I've checked good running Stihl 660's around 150psi as well. If it was reading 180psi THEN 150psi a week later I'd be concerned.

 

[Mastermind]

no, again i am stating there may or may not be an issue with that particular saw.150 psi is in spec per the service manual. do you have one of those? i would guess not, anything else you wish to know? for the record, my well used 261 is right @ 158psi, should i remove the base gasket and 1/2 off the base so it makes 200psi, or run it another season then freshen it up? please enlighten us all oh king of the saw builders.

What I do to a modded saw has no bearing on this issue. That's why we're discussing what normal compression is on a stock 261. In all cases, except yours, of course, compression is 170-180. For you to suggest anything other than to proceed with caution, is highly uninformed, careless, and unprofessional. You seem to believe that since it's a Stihl, there can't be anything wrong with it. Bad information it's worse than no information.

If 150psi is within spec, I bet it is the lower part of the range and not appropriate for a new saw, broken in or not. My very lightly used (I have run 3.5 tanks--previous owner probably didn't put more than a couple of tanks through it) 261 blows 160+. I checked it bf work this morning just for this thread.

Well the piston/cylinder checked out, and it runs as good as new. I had him redo the compression and it was at 155psi on the 2nd test. This one is a tough decision.

Call me silly, but every saw in the same model I've tested had different compression, and sometimes the variance is quite large, same with P&C quality, combustion chamber size, squish gap you name it. There is no set number within reason. My .02

My MS261 was 160psi when I sold it and my standard Huskies tend to hang around 150-155psi. This is within spec according to most information sources. I've checked good running Stihl 660's around 150psi as well. If it was reading 180psi THEN 150psi a week later I'd be concerned.

Well can I chime in without kicking kicked in the sack?

I've yet to see a stock 261 with over 170psi even after being well used.

 

[SawTroll]

there is not thing wrong with that saw, just as suspected. but NONE of us had know real way of knowing for sure. i would not be afraid of it at all, they really are great saws, and you will love it.

Maybe not, but none of us has any way to know for sure. :msp_unsure:

 

[STIHLTHEDEERE]

Well can I chime in without kicking kicked in the sack?

I've yet to see a stock 261 with over 170psi even after being well used.

i would say there would be some variance in psi, method of testing, and testing equipment used on any saw, in any situation. there can be alot of variables,i have many older saws that have always been 145-155 since i have owned them, and they still run great.

 

[STIHLTHEDEERE]

Maybe not, but none of us has any way to know for sure. :msp_unsure:

is that not what i just said?

 

[nmurph]

STD, what is the acceptable range for a 261?

 

[STIHLTHEDEERE]

Stihl says repair/replace "a" clyinders @ 130psi & "b" cylinders @ 135psi not sure what a & b cylinders are, but i did see an email a while back on a different cyl. For the 261. We are starting to see some mahle jugs on thew new stihl saws again.

 

[blsnelling]

Is that specific to a 261?

 

[STIHLTHEDEERE]

again, just passing info from the service/shop manual for the 261

 

[nmurph]

So, I don't see a range. What I see a tech spec saying when to replace a piston. If a 261 should be at least 135psi or be replaced, that saw has lost significant power if it started at 150+.

My (somewhat limited) take on compression-

When prepping saws to sell, I replace a piston if I see more than a 10psi drop from what I expect. I know this is probably not feasible and most customers are going to balk at a $200 dealership shop bill for a few pounds of compression, but I feel better and know I am selling a saw that doesn't have rings/piston on the decline.