Makita petrol chain saw fault

[andrewcollier]

My Makita petrol chain saw starts O.K., but dies when I press the throttle. On starting it sounds as if it running very fast, running away with itself.

Any ideas please?

Thanks

 

[Burnerman]

You're going to have to be brave and strip the carburettor out, I'm afraid....it sounds like the saw is running on a lean fuel / air ratio due to some debris in there.
Basically these carbs have two flat ends.....under one end is a pump diaphragm (that pumps fuel from the tank into the carb) and the other end covers a metering diaphragm (that supplies fuel to the jets).
By all means remove these end plates (one has one central screw, one has four screws) and check the diaphragms for splits......then its out with the carb cleaner aerosol to wash things out. Remove the needle valve (another screw holding the needle, spring and pivot bar) and wash that area through.
Personally I don't do these without a compressed air supply, and kitchen paper is a huge no-no.
Just to further brighten your day, the carb may have 2 adjusting screws with no screwdriver slot, but rather a tiny notch in the end - and a special tool is used to adjust them.
Fish out the filter in the fuel tank if you can - they don't often block but its worth a look anyway.
John