Inspection And Servicing; Cylinder Head - BRP Johnson 4HP Service Manual

INSPECTION AND SERVICING

NOTE:
If excessive wear, cracks, defect or other damage is found on
any component, replace.

Cylinder Head

1. Remove all carbon from the combustion chamber.
NOTE:
•
Do not use any sharp edged tool in order to scrape carbon
off the cylinder head or the head components.
•
Be careful not to scuff or nick the metal surfaces when
decarboning.
2. Inspect the cylinder head for crack in the intake and the
exhaust ports, the combustion chamber and the head
surface.
Valve seat
Inspect the valve seats for crack or other damage.
Cylinder head distortion
Using a straightedge and the thickness gauge, measure the
gasket surface of the cylinder head at a total of six locations
as shown in the figure.
 Thickness gauge
Cylinder head distortion:
Service limit: 0.05 mm (0.002 in)
If the measurement exceeds the service limit, resurface or
replace the cylinder head.
NOTE:
The cylinder head can be resurfaced, using a surface plate
and a #400 grit wet sandpaper.
Move the cylinder head in a figure eight pattern when sand-
ing.
POWERHEAD
INSPECTION AND SERVICING
6-11