260 Compression at 120psi?

[Bigbob]

Hi folks!

I tested the compression in the recent ebay (turning out to be a project saw) and it is 120psi. I hope i did the test correct. With carb and muffler REMOVED I threaded the tester in the plug hole and then turned the crank over and over until the pressure topped out at 120psi.

So, I take it from other threads that this needs new rings. The cylin. wall is smooth with no deep scores or ridges. Can I just put in a new set of rings? Or should I have the cylin. polished?

The more I get into this the more I think I'm going to put it back up on ebay. If anybody is interested in the saw let me know.

MS260 20" bar starts and runs fine.

Again, thanks everybody for all your help and expert advise.

Robert
Bigbob

 

[oldsaw]

Hi folks!

I tested the compression in the recent ebay (turning out to be a project saw) and it is 120psi. I hope i did the test correct. With carb and muffler REMOVED I threaded the tester in the plug hole and then turned the crank over and over until the pressure topped out at 120psi.

So, I take it from other threads that this needs new rings. The cylin. wall is smooth with no deep scores or ridges. Can I just put in a new set of rings? Or should I have the cylin. polished?

The more I get into this the more I think I'm going to put it back up on ebay. If anybody is interested in the saw let me know.

MS260 20" bar starts and runs fine.

Again, thanks everybody for all your help and expert advise.

Robert
Bigbob

If the cylinder still looks nice, and the piston is in good shape, you can probably get by with just new rings. At 120 lbs, you will be below marginal for compression, but was the cylinder wet or dry when you did it? That may get you a few more pounds. At an actual 120 lbs I don't think it would run very well.

Mark

 

[Lakeside53]

Check your tester. There have been volumes written on AS about the "right" tester, but unless it has a schrader valve right at the screw-in tip, it will read very low on a good engne - 120 is what my my old tester showed on 026's... and was actually 155.

 

[Bigbob]

Check your tester. There have been volumes written on AS about the "right" tester, but unless it has a schrader valve right at the screw-in tip, it will read very low on a good engne - 120 is what my my old tester showed on 026's... and was actually 155.

I hear ya! But this tester had one in the end of the hose plus a release valve up near the dial.

Can you get any decent results with swapping the top and lower rings?

Thanks for the quick reply.

 

[Lakeside53]

Nope... swapping rings at that stage will do little...

You can get a new GENUINE STIHL/MAHLE piston and rings for an MS260 for about $25 on ebay right now.. Make sure you measure your cylinder - you could have a 44 or a 44.7mm verison.

 

[Simonizer]

I NEVER do a compression test on a 2-stroke engine. It can tell you if it is completely screwed, but it can't tell you if it is good. Once the gas has evaporated from the cylinder wall and only oil is left behind, you can get a good compression reading from a saw with NO piston rings. I have done this as a demo. A visual inspection tells you everything you need to know. For the 15 minutes it takes to disassemble the top end, there is no need to play around with a compression gauge. Cheers, Simon.

 

[Lakeside53]

hmmm... I can't get a good compression reading from "any saw...". I find the compression a good measure, but yes, you can get fooled. In this case, he's way low...


So Simon... you can take an MS200T down for inspection in 15 minutes?

 

[Simonizer]

hmmm... I can't get a good compression reading from "any saw...". I find the compression a good measure, but yes, you can get fooled. In this case, he's way low...


So Simon... you can take an MS200T down for inspection in 15 minutes?

We are talking about an MS260.

 

[Lakeside53]

We are, but you changed it to "2-stroke engineS", and used the NEVER word..

 

[fishhuntcutwood]

Andy my friend, you are a verbal ninja. This is why I never joust with you. :hmm3grin2orange:

 

[Bowtie]

The more I get into this the more I think I'm going to put it back up on ebay. If anybody is interested in the saw let me know.

MS260 20" bar starts and runs fine.



Robert
Bigbob

So, what you asking for this old junk 026?

 

[Lakeside53]

I was thinking the same thing:hmm3grin2orange:

 

[Simonizer]

We are, but you changed it to "2-stroke engineS", and used the NEVER word..

My Bad. Sorry. Trust me though, I have a "bit of a clue" about saws. Cheers, Simon.

 

[Bigbob]

So, what you asking for this old junk 026?

Well, I paid $189 for it. I was thinking about putting the rings in it putting her back together and selling it on ebay for around $225-250 Does that sound reasonable?

 

[bcorradi]

You'll probably be able to get that for it. Right now is a low time for saw prices on ebay. If you wait till late summer/early fall the prices will start to go back up again. Right now is a good time to buy project saws though.

 

[bcorradi]

Simon - could you repost that pic of you in your shop? Everyone will be able to see they are indeed messing with THE "2 cycle surgeon"?

 

[Simonizer]

Simon - could you repost that pic of you in your shop? Everyone will be able to see they are indeed messing with THE "2 cycle surgeon"?

I have deleted those pics. Too many "Doogie Howser" analogies ha ha. If they knew I was a red-neck cranky bastard they would have a tarnished image of me. I have battled looking too young to know of what I speak for 20 years, oh well. Cheers buddy.

 

[bcorradi]

LOL nice to see you posting on AS again.

 

[West Texas]

Andy, if the 120lbs of compression he's getting, is a true reading, my gut tells me that a piston/ring set is not going to make it a new saw. Cheap as top end kits are for the 026/260 series, I'd be tempted to just put a new top end on it and have the assurance of knowing its going to be a good saw. Course I'm being hypothetical, cause as Simon seze, I can't make a visual inspection from here. opcorn:

 

[Bigbob]

Andy, if the 120lbs of compression he's getting, is a true reading, my gut tells me that a piston/ring set is not going to make it a new saw. Cheap as top end kits are for the 026/260 series, I'd be tempted to just put a new top end on it and have the assurance of knowing its going to be a good saw. Course I'm being hypothetical, cause as Simon seze, I can't make a visual inspection from here. opcorn:

Well, I'll sell it to you for $225 (plus shipping) and you can put a new kit on it. I'll even give you a new carb with the High adjuster.

Bigbob