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Stihl 028 super rebuild went bad

acarpenterdad

acarpenterdad

I like Husqvarna chainsaws...
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Sounds like just another case of damage from running a saw that was set too lean on the high speed mix. You really have to learn to tune the saw so that it has the 4-stroke burble at full throttle out of the wood and just barely cleans out as you start the cut. Unreliable things to go by are the number of turns out on the mixture screws, how much power you think it is making, setting the high rpm to some number with a tach, how well it starts and idles.
Set the H screw so rich that it burbles and runs slow and rough in the cut, stop the saw and turn the screw in a bit and make another cut, keep doing this until you reach the point where the engine just cleans out and runs nice and crisp in the cut. Stop there, should only take 4 o5 cuts to reach the sweet spot.
Thanks!
 
Okie294life

Okie294life

Small engine jackwagen.
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My saw that I just rebuilt last sept. Had the piston fail. A lot of you guys walked me through how to fix it at that time. Ive cut a couple of cords with it and it ran great. In hindsight, it did get harder to start about a month ago. The last time i used it, i set it down to gas it up and it wouldnt restart. After trying different things i put a compression tester on it. 30 psi. . I pulled the cylinder and the exhaust side off it has scuff marks and the piston is ground up on that side only. I certainly thought id get more use out of it than that. What do you think caused the failure?
Air leak sound the seals or your cylinder head bolts are stripped allowing air, or your intake boot/impulse line sucking air.
 
Ax-man

Ax-man

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I would say Old 2 stoke is making a good call. I don't think those old 028's turned much more than 10 to 12 thou at WOT. You really can't tune those older Stihl's like the newer ones . To me those older saws had a slight lag when you went from idle to WOT when you do get them set right instead of a quick sharp throttle response like the newer generation of Stihl's.
 
NIP Group
jp233

jp233

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Yep the Stihl 028 service manual calls out "Max permissable engine speed = 12,000 rpm" Ax Man I think you are right, newer saw models are just more snappy off-idle, build revs very quickly.
 
Mad Professor

Mad Professor

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Sounds like just another case of damage from running a saw that was set too lean on the high speed mix. You really have to learn to tune the saw so that it has the 4-stroke burble at full throttle out of the wood and just barely cleans out as you start the cut. Unreliable things to go by are the number of turns out on the mixture screws, how much power you think it is making, setting the high rpm to some number with a tach, how well it starts and idles.
Set the H screw so rich that it burbles and runs slow and rough in the cut, stop the saw and turn the screw in a bit and make another cut, keep doing this until you reach the point where the engine just cleans out and runs nice and crisp in the cut. Stop there, should only take 4 o5 cuts to reach the sweet spot.
what he said ^^^^^ with a sharp chain and clean AF
 
RED-85-Z51

RED-85-Z51

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Reading a plug like that is hard...normally youll want to kill it at full throttle at the end of a cut.

Sent from my LM-G820 using Tapatalk
 
Bob Hedgecutter

Bob Hedgecutter

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I have the clutch off. Now i havta get the tool to take off the flywheel.
On an 028? No specific tool needed- back the nut off a bit and whack the end of the crank- center punch in the divot of the crank if your aim is no good, otherwise use a copper faced hammer or a rubber mallet. I can split cases with a rubber mallet up to about 046 size.
 
acarpenterdad

acarpenterdad

I like Husqvarna chainsaws...
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Jan 4, 2019
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indiana
Results. Vacuum, started at 10", took about 2 minutes to get to 5". Pressure, pumped to 10psi and it held for a couple of minutes. I used soapy water to check for leaks and nothing showed.
 
Bob Hedgecutter

Bob Hedgecutter

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Results. Vacuum, started at 10", took about 2 minutes to get to 5". Pressure, pumped to 10psi and it held for a couple of minutes. I used soapy water to check for leaks and nothing showed.
Thats good- no leaks (you checked the manifold eh?) and correct fuel mix ratio- means you can blame your tuning.
 
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