Honda CRF450R 2020, Owner'S Manual & Competition Handbook

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Servicing Your Honda
93
Piston/Piston Rings/Piston Pin
1. Clean the cylinder mating surfaces (1) of the
crankcase, being careful not to let any material
fall into the crankcase.
2. Remove the shop towels.
3. Apply liquid sealant (TB1141G manufactured
by ThreeBond or equivalent) to the cylinder
mating surface of the crankcase side as shown.
4. Install the dowel pins (2) and a new cylinder
gasket (3).
Do not let the dowel pins fall into the crankcase.
5. 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.
Do not damage the piston rings and cylinder bore.
Do not let the cam chain fall into the crankcase.
Cylinder Installation
(1) cylinder mating surface
0.2 – 0.4 in
(5 – 10 mm)
0.2 – 0.4 in
(5 – 10 mm)
(1)
(2) dowel pins (3) cylinder gasket (new)
(2)
(3)
(4) cylinder bore (6) cam chain
(5) piston rings
(6)
(5)
(4)