Valve Guide Replacement; Cam Chain Tensioner/Guide - Honda 2003 NPS50 Ruckus Service Manual

Ream the valve guide to remove any carbon build
up before measuring the guide.
Insert the reamer from the combustion chamber
side of the head and always rotate the reamer clock-
wise.
TOOL:
Valve guide reamer, 4.508 mm 07HMH-ML00101 or
M easure each valve guide
_
SERVICE LIMIT: IN/EX:4.54 mm {0.179 in)
Subtract each valve stem 0.0. from the correspond­
ing guide I. D. to obtain the stem-to-guide clearance.
SERVICE LIMIT:
IN: 0.075 mm {0.0030 in)
EX: 0.085 mm {0.0033 in)
Inspect and reface If the stem-to-guide clearance exceeds the service
the valve seats limit, determine if a new guide with standard
whenever the valve dimensions would bring the clearance within toler­
guides are replaced a nee.
(page 9-13). If so, replace any guides as necessary and ream to
fit.
If the stem-to-guide clearance exceeds the service
limit with new guide, also replace the valve.

CAM CHAIN TENSIONER/GUIDE

Check the tensianer and guide far excessive wear or
damage.
If necessary, replace them using the fallowing pro­
cedure.
Remove the oil pump driven gear {page 5-4).
Remove the dowel pin and cam chain tensianer.
Remove the cam chain guide from the cylinder and
crankcase grooves.
Remove the cam chain.
Coat the cam chain and timing sprocket with ail.
Installation is in the reverse order of removal.

VALVE GUIDE REPLACEMENT

Chill the replacement valve guides in a freezer far
about 1 hour.
Heat the cylinder head to 1 30 'C - 140 'C {275 'F -
Be sure to wear
290 'F) with a hot plate or oven. Do not heat the cyl­
heavy gloves to
inder head beyond 1 50 'C {300 'F). Use temperature
avoid burns when
indicator sticks, available from welding supply
handling the heated
stares, to be sure the cylinder head is heated to the
cylinder head.
proper temperature.
Support the cylinder head and drive the valve
Using a torch to
guides out of the cylinder head from the combus­
heat the cylinder
tion chamber side.
head may cause
warpage.
TOOL:
Valve guide driver, 4.5 mm
07HMH-ML0010B o r
07HMH-ML0010A
{U.S.A. only)
1.0.
and record it.
07HMD-ML00101
CYLINDER HEAD/VALVES
REAMER
GUIDE DRIVER
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