Honda CRF250R 2018 Owner's Manual page 90

4. Apply engine oil to the cylinder bore (4),
piston outer surface and piston rings (5). Route
the cam chain (6) through the cylinder. Install
the cylinder over the piston rings by hand
while compressing the piston rings.
NOTICE
Do not damage the piston rings and cylinder bore.
Do not let the cam chain fall into the crankcase.
(6)
(5)
(4) cylinder bore
(5) piston outer surface and piston rings
(6) cam chain
5. Temporarily tighten the cylinder bolt (7) with
a new sealing washer (8).
(8)
(7) cylinder bolt (8) sealing washer (new)
Cylinder Head Installation
1. Clean any gasket material off cylinder head.
2. Install the dowel pins (1) and a new cylinder
head gasket (2).
NOTICE
Do not let the dowel pins fall into the crankcase.
(4)
(1)
(1) dowel pins
(2) cylinder head gasket (new)
3. Route the cam chain (3) through the cylinder
head and install the cylinder head (4).
(7)
NOTICE
Do not damage mating surfaces when installing
the cylinder head.
Do not let the cam chain fall into the crankcase.
Piston/Piston Rings/Piston Pin
4. Apply engine oil to all cylinder head B bolt
threads and seating surface.
Install the washers (5) and cylinder head B
bolts (6) and tighten them to the specified
torque in a crisscross pattern in two or three
steps:
35 lbf·ft (48 N·m, 4.9 kgf·m)
NOTICE
Do not let the washers fall into the crankcase.
(5) (6)
(2)
(3)
(3) cam chain
(4) cylinder head
(5) washers
(6) cylinder head B bolts
(4)
(cont'd)
85
Servicing Your Honda