9. Crankcase and Piston Skirt Clearancing (All)
NOTE: Many of the clearancing operations described in this
section can be done simultaneously as the same set-ups are used.
Please read this entire section before beginning work.
Insuf
ficient clearance between connecting rods and
crankcases, pistons and flywheels, and between the two
pistons will cause contact and damage to components.
A. Connecting Rod Clearance - Front and rear of flywheel
cavity inside crankcases and cylinder spigots must be
clearanced for connecting rods.
See Pictures 10 and 11.
Procedure to check these points is performed as follows:
1. Mock up flywheel assembly in right crankcase half
with bearings, etc. in place.
2. Assemble pistons without rings on their proper
connecting rods, and place connecting rods on
crankpin. Installation of wristpin clips is not necessary.
NOTE: All S&S
®
Sidewinder
®
kits have piston to piston clearance
notch cut in the front skirt of rear piston. Rear piston must be
installed with notch toward the center of engine.
3. Install both cylinders and secure each with one
head bolt.
4. Rotate flywheel until r
ods contact ar
eas to be
clearanced. Note angle that must be filed.
5
. Disassemble cylinder and connecting rods and file
crankcase and cylinder spigot for clearance.
See
Picture 12.
NOTE: A minimum of .060" clearance is required between
connecting rods and crankcase and cylinder spigots.
6. Reassemble and check clearance.
7
. Mark and grind other crankcase half to identical
clearance.
B. Piston Clearance - Piston clearances must be checked to
a
void piston to piston contact and piston to flywheel
contact. See Pictures 13 and 14.
NOTE: Pistons are normally clearanced in S&S kits, but good
engine building practice demands that all clearances be checked
during assembly. In the event that additional clearancing must
be done, weight of material removed from pistons generally is
too small to significantly affect flywheel balance.
1. Piston to Piston Clearance
a. Perform Steps 1 through 3 in Connecting Rod
Clearance (Step A).
b. Rotate flywheel to position where pistons are
closest to each other. This is at the bottom of
the stroke.
See Picture 13.
c. Check clearance between pistons.
NOTE: A minimum of .060" clearance is required between piston
skirts at the bottom of the stroke.
d. If clearance is not sufficient, disassemble cylinders
and pistons, and carefully file notch in front skirt
of rear piston until clearance is obtained.
NOTE: The rear skirt of the piston is the primary thrust face, and
carries the greatest load during engine operation. For this
reason, piston to piston clearancing is done on the front skirt of
the r
ear piston in order to leave the rear skirts of both pistons as
long as possible.
e. Reassemble and recheck clearance.
8
Picture 10
Picture 11
Picture 9
CAUTION
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals