Stihl 028 compression spec - need confirm

Spoke to a Stihl tech today, a guy who seemed to know what he was talking about. He referenced a Stihl Tech book ( for Techs only ) for my 028, 44mm that said specifically that the compression should be 120-125.

This is different from what I've read and want to verify it. I know a comp of150 is a # thrown around a lot, but is that for my saw or a bigger Stihl ?

Don't know about this saw but I have measured many saws and 125 psi is bare minimum IMHO 150 psi is pretty decent in most saws and have had 175psi on my 345 and 630 as they have not had much use. My 181 runs at 160 and that is 80cc so your 120-125psi seems very low to me.

I have had 125psi on an L65 and found the piston to be fried!

Spud

what was your saw's compression? are you near sea level?

In my experience,anything over 130 is good, 150 is better. Have heard of numbers like 200 but never seen it .

125 would be the low limit before repair 150 just right.

nate cutter said:

what was your saw's compression? are you near sea level?

Click to expand...

Yes, fresh shrimp always helps.......

If I'm lucky, 15' above sea level !

My saw is at 100 comp ! Bad - I know !

I hear you all - and I appreciate your input...

But, this hi volume Stihl dealer's tech looked up the saw compression in a Stihl tech manual - said it should be around 120-125lbs.

Anyone have an 028 ? and can verify this ?

Or, are there any Stihl tech's that have access to a ' tech manual ' ?

I just don't want to be chasing 150lbs if that ain't gonna happen...

just got your reply went out to the shop put the snap on compression tester in and 170lbs

abl1111 said:

Spoke to a Stihl tech today, a guy who seemed to know what he was talking about. He referenced a Stihl Tech book ( for Techs only ) for my 028, 44mm that said specifically that the compression should be 120-125.

This is different from what I've read and want to verify it. I know a comp of150 is a # thrown around a lot, but is that for my saw or a bigger Stihl ?

Click to expand...

What was the name of the store?

Ignore the comp. gauge, and pull the muffler and look at the piston next.

any bets on scoring?

Any shrimp in New Jersey??

Or just crabs?

"But, this hi volume Stihl dealer's tech looked up the saw compression in a Stihl tech manual - said it should be around 120-125lbs."


A very good friend obtained a well used 028WB. It was pretty "weak" as far as power production, but cut OK. We did a compression test on it one day after cutting firewood and it tested right at 120psi.

I removed the muffler and piston looked fine. We went ahead and ringed it anyhow a few months later, thinking it might raise the compression a bit and improve power. Well, it did neither. The compression after running it in was EXACTLY 120psi. The cylinder bore and piston were in perfect shape, the new rings set well, and the saw is stilling running fine today.....Cliff

Fish said:

Any shrimp in New Jersey??

Or just crabs?

Click to expand...

all of it.

Cliff R said:

"But, this hi volume Stihl dealer's tech looked up the saw compression in a Stihl tech manual - said it should be around 120-125lbs."


A very good friend obtained a well used 028WB. It was pretty "weak" as far as power production, but cut OK. We did a compression test on it one day after cutting firewood and it tested right at 120psi.

I removed the muffler and piston looked fine. We went ahead and ringed it anyhow a few months later, thinking it might raise the compression a bit and improve power. Well, it did neither. The compression after running it in was EXACTLY 120psi. The cylinder bore and piston were in perfect shape, the new rings set well, and the saw is stilling running fine today.....Cliff

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I could send pics if you like and dealers dont know everything and are not perfect thats low compression no matter what what is the piston to wall clearance it should be a few thousandths? maybe a new piston would fix it.

lone wolf said:

I could send pics if you like and dealers dont know everything and are not perfect thats low compression no matter what what is the piston to wall clearance it should be a few thousandths? maybe a new piston would fix it.

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he shoudnt have to look it up

Lone Wolf - thx for doing the compression test on your saw - was that done on an 028 ?

Cliff - sounds like your buddy's saw is a lot like mine.

Wiggle - the name of the store is: LI Power Equip, Farmingdale, NY 631 293 0777 - spoke to Joe 'the' tech...

- I have taken the piston off and the cylinder ( too many times already !). I posted some P&C pix on another thread today. There is no scoring on the piston. The cylinder looks clean, but I don't know enough about what's acceptable or not.








It has been an interesting diagnosis...

028 you need to check piston to wall clearance to determine the cond of the piston also what is the ring end gap?

I never said 120psi cranking pressure was "ideal". The 028 WB we re-ringed came in here with 120psi, and left here with 120psi. There was no piston or cylinder wall damage, ring grooves were tight, ring end gaps were fine, piston to cylinder fit was good, and the cylinder wall had no damage and was lightly finished with some 600 grit auto body sandpaper during the rebuild. That was at least 2 years ago, and it's been cutting firewood ever since, and doing a fine job of it. I did notice that it wasn't an overly powerful saw, but I haven't ran enough of them to know how strong they were right to start with? You also have to ask yourself, "does it really matter for a work saw?" If it starts easy, and runs fine on every outing, does it matter if it has 120psi cranking pressure or 140psi?.....Cliff

Cliff,

Thank you for that entry - you are right! If it works... why not just use it ? As a matter of fact, I've never used it to cut anything.

I figured I'd get the saw 'right' first and then have a good saw ( and get rid of (2) 1970's Craftsman saws that I have - that work GREAT ! )

Unfortunately for me, my personality dictates that anything mechanical I have is as close to mechanically perfect as I can make it. It's a curse !

I am challenged to understand, find parts for and repair this thing. I have the ability to fix it, although I have never looked at a 2 stroke motor in my life... Some people finish puzzles, paint, read or watch TV in their spare time - my brain needs a mechanical puzzle !

This Stihl has more than fit the bill.

This site has been so helpful and patient - I truly thank everyone for their assistance.