Tunning specification for a stihl 028 chainsaw?
I'm not sure there are any "endorsed" tuning specs from Stihl as weather, temperature, fuel quality etc all contribute to engine performance.
Pictures of all types are all over the web.
As for the carb tuning procedure, maybe I can help?
Start with fresh fuel, all filters clean, and bar and chain installed. Also, fill the chain oil tank with bar/chain oil and VERIFY that the chain oiler works properly.
Initial fuel mixture settings (the H and L screws) should be 1.5 - 2 complete revolutions counter clockwise from lightly seated. Sight the carb's throttle plate and adjust idle screw counter clockwise until the plate stops moving.(Throttle closed completely.) Then go back clockwise 3 complete revolutions. This will produce an acceptable startup condition on a HEALTHY saw.
Clamp the bar in a STURDY bench vise and roll the chain with the shank of a screwdriver to verify it is clear. BE SAFE!
Choke the saw and pull the starter rope until the engine "burps".
NOTE: If no burp after 6 pulls, stop! Something is wrong.
After the burp, set choke to half and pull starter until it runs. The settings I gave should produce a slightly rich condition and a slightly high idle. (Chain will be in motion!)
Blip the throttle trigger and idle it down just enough to keep it running during the tune procedure.
Step 1) Using the "L" screw (closest to the engine), turn it clockwise until the engine smooths out or possibly increases RPM. Back it out slightly until the engine has a slight "LOPE" sound to it. (Like a drag car on nitro).
Step 2) Accelerate the engine to full throttle and go to the "H" screw (closest to the air filter) and slowly turn it clockwise and note the RPM increase. There will come a point when the saw will "Top-Out" and loose power. Not even enough power to turn an maintain empty chain's RPM! Go back counter clockwise to the edge of that point, and counter clockwise another fourth (1/4) revolution.
Step 3) Idle the saw back down. Again go to the "L" screw and repeat Step 1.
Step 4) Repeat Step 2.
Step 5) Idle the saw down until the chain stops moving completely. NOTE: Don't settle for a "crawling chain" condition. If the steps above are performed well and all else is healthy, you should be able to idle the engine down to a ridiculously low RPM and it will not shut off.
Hope this helps,
Oct 13, 2009 |
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