Honda CRF450X 2020 Owner's Manual & Competition Handbook page 103

Cylinder Installation
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.
(1)
0.2 – 0.4 in
(5 – 10 mm)
0.2 – 0.4 in
(5 – 10 mm)
(1) cylinder mating surface
4. Install the dowel pins (2) and a new cylinder
gasket (3).
NOTICE
Do not let the dowel pins fall into the crankcase.
(2)
(2) dowel pins (3) cylinder gasket (new)
Piston/Piston Rings/Piston Pin
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.
NOTICE
Do not damage the piston rings and cylinder bore.
Do not let the cam chain fall into the crankcase.
(6)
(3)
(4) cylinder bore
(5) piston rings
(4)
(5)
(6) cam chain
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Servicing Your Honda