before reading further, if your fuel is over 8 weeks old, get fresh fuel and run a tankfull through the saw before fiddling too much, fuel goes stale real quick these days and is the cause of most running problems.
1. check the chain is sharp and not too tight (you should be able to slide the chain along the bar with a moderate grip between finger and thumb).
2. Is chain being oiled sufficiently? Always use proper chainsaw chain oil, others are not good enough!
3. are you using the correct fuel mix? 50 to 1 is factory recommended which is fine if you use a good quality synthetic two stroke oil. If using mineral or cheap oil go up to 36 to 1 and re-adjust carb to suit.
( I use good oil at 40 to 1, it makes the plug foul occasionally but my equipment lasts for years!)
4. Adjust the carburettor. The engine will require a richer mixture when cutting than when revved with no load. Try richening the high speed mixture an eighth of a turn or so. if the screws are restricted by plastic knobs fitted on them, prise them off to do this.
5. I know you said you had cleaned the carb and exhaust... was the metering diaphragm (with the metal disk) nice and flexible? they go hard and then don't work correctly resulting in either a weak mixture or flooding. did you replace the fuel filter, they clog over time and cannot be cleaned if of the fabric mat type. hook the fuel line out of the tank with a piece of bent wire. Also, the exhausts often have a fine woven mesh across the exhaust outlet to suppress sparks. these can be removed and burned clean with blow torch before refitting.
Those are my thoughts on it, good luck
Jules
October 2009
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