Thursday, August 12, 2010

Another Chainsaw Carburetor Lesson





BLSnelling posted an excellent video and explanation on Arboristsite which demonstrates what you should listen for when setting the high speed mixture on your chainsaw. Here is Mr. Snelling's article:

"There's more to tuning a chainsaw than just adjusting the high end, but this is a start. It also gives an excellent example of what 4-stroking sounds like.

In the first cut, the saw continues to 4-stroke, even towards the bottom of the cut. That's a little too rich. It should run clean all the way through the cut once under load.

After that first cut, I tune the H screw. I turn the H screw in clockwise until the engine peaks out and is totally 2-stroking. No 4-stroke at all. I then quickly richen the mixture back up by turning the H needle counter-clockwise. Immediately you hear the engine begin 4-stroking again.

The next cut you can hear the engine immediately clean out once underload, and stay that way for the entire cut. After that cut I rev the saw and you can hear that it is still 4-stroking at WOT. It's important to check for that after a cut, since that's when your saw will be its hottest and leanest."


Those are very clear and concise instructions. Thank You, BL!

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