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SECTION
'10: CYLINDER & CRANKCASE
COVER
It is rccommended that the cylinde. bores be reconditioned
to restore the cross hatch when new piston rlngs are to be
innalled in a cylinderthat iswithin specification.
Be careful not
to hone ove6ize or itwillbe necessarv
to reolace the crankcase.
Honing is donewithava ablespeed L2", podab e drilland
a honing fixture. See Page l0-5 for dimensions to make a
honing fixture. Use tlvo crankcase cover mounting scrcws to
fasten the cr€nkcaseto the honing fixturc, Figure 10-5.
Clarnp honing fixture and crankcase securely in a vise at a
convenient work height.
Plac-" hone in middle of cyllnder bore. Tlghten adjusting
knob with finger untilstones fit snugly against cylinder wall.
DO NOT FORCE. Cut a wood block and place inside rylinder
to prevent hone f.om exrending further than 3/4" to 1 ' (19
mm to 25 mm) below cylinder bore. Place hone dive shaft in
chuck of portable drill and tighten. Be sure that cylinder and
hone are centered and aligned with the drilspindle.
NOTE: To produ.e the prcper (oss hatch finish use a dd
speed of apyoximately 2OO RPM and /P-60 Hatch nrckes
per minvte. Lubfi.ate hone libera y to prevent build up
on finishing stones,
NOTE: Automatic transmission fluid is an accebtable
honing oil. Another ac.eptabte honing oit can be tnade
by mixing 4 patts No. 30 weight oil with I patt kercsene.
with hol running wat€r Repeatwashing
and rinsing unlilallt€ces
oi hon n9 grh a€ gone.
Honing git is highly abGsive and willcause rapid wearto all
ofthe lnternal components of the engine unless ii is completely
Figwe | 0-4. Cylinder Crcss
CLEANING:
IT IS MOST IMPORTANT THAT THE ENTIRE CYLINDER AND
CRANKCASE BE THOROUGHLY CLEANED AFIER HONING.
Finwash thecylinderand
crankcasecareiully
in a solventsuch
as
kercsene or commeKlal
solvent. Then thorough ywash cy inder afd
cGnkcase
using a stiff brush with soap and hotwater Rinsethooughy
Figurc, 0- 5. Honing Cylinde6
NofE: when cylinder and .rankcase have been thor-
oughly cleaned, use a clean white ag or napkin and
wipe the cylinder borc. ff honing grit is prcsent it wi
appear as a gEy rcsidue on rag. lf any honing gfit is evi-
dent re-wash and dnse entirc qlinder and (ankcase and
.heck again. When therc is no tace of honing gfit on hg.
the qtindet is $ope y cleaned. Then oil cylindet borc
to pfevent fusting,
BEARINGS
CHECK
MAG BEAR]NG:
Check magneto bearing for damage. Damaged bearings
must be replaced. Lf not daraaged, check for wear using a tele-
scoping gauge and calper (see Figure 10-6). Measure atseveral
locations. lf the measured diameter is larger than 38.25 mm
(1.506"), the bearing must be rcplaced.
The diameter of the crankshift may also make it necessary
to rep acethe bearing.see Secrion 11 forthe cfankshaft mea-
SuTement detars.
REMOVE
IV1AG BEAR NG:
2.Placecrankcaseflat
upon a pressand remove bearing using
a bushlng driver (Figure 10-7).
raN
,dffiW,r.'\r'4
10-2
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