Another compression question (ms261)

[jggrmson]

So I have a Stihl MS261 that I bought from a member here about 2 years ago. Compression was never brought up and I never really checked. I had a cheap HF tester at the time that I never really trusted it.

I bought a Craftsman compression tester a few months ago and this weekend I was messing around and decided to check it. It was reading 150 cold. I see guys all over this site putting up 180s. The saw does not have any cylinder work on it and has around 25 hours on it.

My first question is...is this normal for a relativity new saw.

Second is does a stock saw's compression vary based on size (cc)

thanks for everything guys.

 

[Guido Salvage]

My first question is whether your tester has a Schrader valve?

 

[jggrmson]

My first question is whether your tester has a Schrader valve?

it an unaltered Craftsman compression tester so yes. should I pull it?

 

[Guido Salvage]

it an unaltered Craftsman compression tester so yes. should I pull it?

Only to release the pressure after finishing your test. How many times did you pull the starter rope? You need to keep going until the needle does not move up, I have had saws where that might be a dozen or more pulls.

 

[jggrmson]

I pulled 10 times or so. I hate not trusting a tool. I hooked it to my compressor which has a tool PSI gauge on it and there is a 5psi difference at ever setting I put it at. The Craftsman gauge reads 5 pounds low.

 

[lone wolf]

Sounds like your saws compression is OK.

 

[Guido Salvage]

As long as the saw starts, runs and performs as it should, I would not be too concerned with the compression reading.

 

[jggrmson]

Sounds like your saws compression is OK.

I figured this would be the reply. I'm just looking for the price of mind that this is normal for a fairly new saw

 

[lone wolf]

I figured this would be the reply. I'm just looking for the price of mind that this is normal for a fairly new saw

Little low it should be 160 - 170 IMOHO

 

[blsnelling]

Little low it should be 160 - 170 IMOHO

I concur. What is your elevation?

 

[lone wolf]

I concur. What is your elevation?

Sea level

 

[jggrmson]

I concur. What is your elevation?

oh about 20ft....

 

[blsnelling]

Sea level

The OP

 

[lambs]

Mine pulls 160 on my gauge from Bailey's. It has a hose maybe 6" long though, so who knows.

I think yours is fine, especially if it's actually 155.

 

[jggrmson]

The OP

Hey Brad. This is a saw that came across your bench once upon a time.

It just doesn't make since that this saw would be so low. The original owner claimed 45:1 Ultra: easy 10 hours. I have only put 5ish more hours on it (been deployed)

 

[blsnelling]

Hey Brad. This is a saw that came across your bench once upon a time.

It just doesn't make since that this saw would be so low. The original owner claimed 45:1 Ultra: easy 10 hours. I have only put 5ish more hours on it (been deployed)

What did I do to it? If the base has been cut to tighten the squish, it should be closer to 190.

 

[jggrmson]

What did I do to it? If the base has been cut to tighten the squish, it should be closer to 190.

nothing that fancy. Original seller claimed you did a MM and timing advance. I never pulled the flywheel to check, but the "fined MM" looks professionally done.

 

[LowVolt]

My craftsman gauge (mityvac) has been very reliable compared to others I have tried.

If it was my saw I would be pulling the muffler to have a looksy.

 

[SCHallenger]

Mine was 165 after 25 tanks through it. Brad tightened the squish & raised it to 190.

 

[jggrmson]

Mine was 165 after 25 tanks through it. Brad tightened the squish & raised it to 190.

Thanks. That's what I was expecting to see.