Honda ST50 Shop Manual page 21

c. After the new vavlc guide has been in-
stalled, it must
be
reamed to the proper
fin ish size with a guide reamer (Tool No.
07984-0980000).
Excercisc care
when
usi-ng the reamer and occasionally apply
a small amoun of oil to the reamer
when it becomes diffi.cull to use. Pull
the reamer out and remove the metal
chip before con1inuing to ream.
The standard vavle guide inside diamerer
is 5.475-5.485 mm (0.2 156-0.2159 in.).
(Fig. 24).
6. lnspcctingthevavlespring
Measure the vavle spring free length with
a vernier caliper.
(Fig.
25)
Flg.24
Fig. 25
I•m
Standard Valve
lnnervalvespringfreelength
Outer valve spring free length
Inner valve spring compression
Outer valve spring compression
7. Inspectingthc:. camshaft
Measure the cam lift with a micrometer (Fig.
26). mm (inch)
lift
(including
'"'""'
circle:)
Val.,-e Timing
Intake opens
Intake closes
Exhaust opens
IW!aust clmes
26.076
( 1.0266)
Replace if
under
25.8 (1.012)
5° BTDC
211• ATDC
25° BBDC
5° BTDC
Micrometer
Flg.26
19
mm {i nch)
Scrviccab!cLimi1
Replace 1fundcr 23.9
(0.941)
Replace if under 26.9
(1.059)
Replace 1fundcr 2. 0kg/ 22.7
(4.4Jlb/ 0.894in)
Replace 1f under4.6kg / 24.9
00.J4 lb/0.980 in)