BRP Johnson 4HP Service Manual page 84

POWERHEAD
CYLINDER / PISTON / CRANKSHAFT / CONROD / CAMSHAFT
7. Remove the piston with the conrod through the top of the
cylinder bore.
8. Remove the crankshaft from the cylinder block.
9. Remove the circlips 7, the piston pin 8, the conrod 9
and the piston ring set 0 from the piston A.
6-10