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Stihl MS290 : Carb Adjustment

Posted by Workinguy OR (My Page) on
Mon, Aug 27, 12 at 14:08

My saw died and taking it apart the cylinder/piston were scored. I bought a new cylinder housing and piston and put it back together, Ran through a gallon of gas and the piston scored again. The cylinder housing has no scratching but I did clean it out since it appeared there was some melted Aluminum from the piston toward the top. Bught a new piston and is running fine....
New impulse line
New Carb kit installed
New fuel line
New crank seals
New bearings
Used Si gasket for sealing in crank.
Using 40:1 mixture (definitely blue)

So I have not used it to cut yet since the underlying issue does not seem to be resolved. It idles fine and when I rev er up and adjust the high side carb screw I do not notice any change in RPM pitch... screw fully in our out and of course with the throttle fully open. The screw only travels 3/4 rotation. Is there something I am missing here?

Follow-Up Postings:

RE: Stihl MS290 : Carb Adjustment

You need to trim the limiters on the carb adjusting screws and adjust the high richer, also any carb cleaning job would include taking the adjusting screws out and cleaning the passage under them... A few reason why saws get lean are they are set a bit lean from the factory for the EPA, ethonal gas make them run leaner and if left sitting the carb will gunk up when using ethonal. Steve

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