Brushcutters

First take a look at your muffler's spark arrestor screen; it may be partially clogged with carbon causing too much back pressure.

When it comes to cleaning and adjustment of the carburetor which appears to be a Zama C1Q-EL11.

• Don't use carburetor cleaner as it will damage internal parts.
• Don't use direct compressed air as will also damage internal parts.
• These carburetors should only be cleaned using ultrasonics with the mixture screws removed. You do not need to remove the welch plug(s) normally when using ultrasonics.
• When install the mixture screws back in the longer one goes in the L (low) speed.
  • Set both mixtures at 1-1/2 turns out from lightly seated position for initial settings.
  • First tune L mixture for best idle speed.
  • Then tune H mixture for best high speed and enrich a little until you get a slight 4 cycling sound.
  • You may readjust the L low speed a little as these are interactive.
• Replace the limiter cap(s) at mid point once your satisfied with your adjustments.

If you replace the gaskets, diaphragms, and metering lever. Make sure put the gaskets and diaphragms in the correct order. The metering diaphragm side is gasket and then the diaphragm. Fuel pump side diaphragm and then the gasket. The metering lever is set using the Z Tool or a straight edge. The height is be level with carburetor metal body.

A couple other things to check.

• The four main screws that hold the cylinder to crankcase are tight. Torqued at 11 Nm. (97 in-lbs)
• That the fuel filter isn't clogged. I don't see many but it does happen.