What could be causing my chainsaw to die after about 5-10 minutes of heavy use, starts ok but bogs untill it cools down, runs well untill it gets warm again. outside temp now is about 5-10 degrees F

I've had similar on a Husky which went on to break a piston ring. Turned out to be a combination of 2 things. The exhaust nuts were lose allowing extra heat to get to the cylinder and the fuel mixture was too weak in terms of oil. First check you're using the correct fuel to oil 2 stroke mixture it does not hurt to add a little extra oil, I suggest trying 40:1 rather than 50:1. Then check the tightness of the exhaust bolts. If they take any tightening then you will probably find you need a new exhaust gasket. Replace if necessary but make sure you tighten the exhaust and re-check the tightness regularly!

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