Remove Fan Wheel: BR 500, BR 550, BR 600.
;
To remove the fan wheel on a
4-MIX®
backpack blower, block the piston with the
piston stop and use a ½ inch breaker bar with a 17 mm. socket to unscrew the fan
wheel. Piston stop STIHL Part # 4282 890 2700.
;
The mounting nut is molded into the fan wheel as one piece and has right hand
threads.
;
It will be extremely tight, and may take one person to hold the engine and fan
housing while another applies pressure to the breaker bar.
;
Do not use an impact wrench on any STIHL product.
Engine De-Carbonizing Procedure.
;
If a 4-MIX® engine is showing more than 10% leakage past the exhaust valve, the
most likely cause is carbon build-up on the valve face.
;
STIHL Engine Decarbonizing liquid
can be used to soften and flush out carbon
deposits. Engine treatment involves putting the piston at top dead center on valve
overlap, where both valves are slightly open at the same time. This is 360° of
crankshaft rotation from top dead center on the compression stroke. With the
valve cover removed this is easy to verify.
;
Then fill the cylinder with the decarbonizing liquid.
STIHL 4-MIX
®
Cam Timing: Backpack Blowers – 4282 Series
