32 Series 4180 Powerhead
– Pull the boot off the spark plug.
– Unscrew the spark plug.
: Screw compression tester 
5910 850 2000 (1) into the spark 
plug hole.
– Move slide control to "STOP-0".
– Set choke shutter to open.
– Pull starter rope vigorously and 
quickly several times.
– Note compression pressure.
If the compression pressure is 
below 6 bar, check valve clearance 
and readjust if necessary, b 7.2.
If this produces no improvement, 
check the cylinder, valve seat, 
piston and piston rings for scores or 
other damage.
The design specification is 6...7 bar.
Reassemble in the reverse 
sequence.
Check and adjust valve clearances 
only when engine is cold.
– Remove the rewind starter, 
b 5.2
– Remove the shroud, b 5.7
: Take out the screw (1). 
– Remove the sealing ring.
– Unscrew the spark plug.
: Remove the valve cover (1).
: Remove the gasket (2).
: Rotate the crankshaft until the 
arrow (1) is in line with the screw 
(2) on the right-hand side of the 
ignition module.
Observe rocker arms while rotating 
the flywheel up to the mark. If the 
valves are operated by the rocker 
arms in this position (valve overlap), 
rotate the crankshaft another turn 
until the valves are idle and the 
arrow (1) lines up with the screw (2).
Turn the crankshaft back and forth 
to make sure the valves are not 
operated in this position.
If there is no noticeable valve 
overlap, proceed as follows: 
7.1 Compression Pressure 7.2 Checking / Adjusting 
Valve Clearance