How to Tune Up a Mantis Tiller
The Mantis tiller/cultivator was designed for easy owner maintenance and repair. If you learn a few simple maintenance tasks, you can keep your Mantis in top shape for many seasons. Each Mantis tiller comes with a DVD and an owner’s manual, both of which have valuable information for the safe operation and maintenance of the tiller.
Check the air filter. Loosen the wing nut on the air cleaner cover and remove the cover. (The choke button fits through a hole in this cover.) The felt-like pad inside the cover is the air cleaner. It should be white. Remove it, and brush off dirt and debris. If the filter is caked with dirt or the dirt will not brush off, replace the filter with a new one. Replace the cover and tighten the wing nut.
Check the spark plug. Remove the spark plug and see if the tip is covered with black deposits. If it is, clean it, or replace it. If the end of the center electrode (the electrode under the “hook”) is worn and rounded, or if the ground electrode (the “hook”) is worn, replace the spark plug. The correct plug is a NGK-BPM8Y set to a 0.6mm to 0.7mm gap.
Check the idle. If the tines turn when the tiller is idling, or if the engine runs fast, you need to adjust the carburetor. The adjustment screw is the metal screw just below the red and white plastic screws under the air-cleaner cover. Turn the carburetor screw counter-clockwise in tiny amounts to adjust the idle. When the tines no longer turn on idle, and the engine runs more slowly and smoothly, the adjustment is correct.
Adjust the High-Speed and Low-Speed on the Carburetor
Check the High and Low screw adjustments on the carburetor. The High-speed adjustment is the red screw, and the Low-speed adjustment is the white one. They are located next to the choke button. The engine will run rough when these are out of adjustment.
Remove the tines from the tiller. Start the engine and let it run for two or three minutes. Close and open the choke several times while it runs to make sure there is no air in the fuel system. Turn the engine off when it has warmed up.
Turn the red high-speed screw all the way counter-clockwise to the stop point. Turn the white low-speed screw so it is halfway between the two stop points.
Start the engine again, and run it on high to get rid of extra fuel. Let the engine idle.
Speed the engine to full throttle a few times, listening for a smooth change from idle to fast. If the engine hesitates when you throttle it, adjust the white screw by turning it no more than 1/8 turn counter-clockwise. Check again by throttling the engine. Keep adjusting in tiny increments until you hear a smooth transition from idle to high speed.