S&S Cycle Bore Big Twin Stroker Kit 1936–1999 3 7/16 - 3 1/2 - Manual (Page 8)

8
Visual Procedure
A. Install pistons on rods without rings or wristpin clips. Bolt cylinders with gaskets in place.
B. Move piston tight towards camside of engine.
C. Turn engine over in normal direction of travel 2 or 3 revolutions and observe piston during process.
D. Move piston towards driveside of engine and repeat Step C. If inaccuracies are present due to machining variations in cases, cylinders or
pistons, top land of piston deck will appear closer to cylinder wall at one point around circumference. This means that piston is cocked in
cylinder bore and can be corrected by bending rod in opposite direction. Figure 3 shows an exaggerated side view of this condition.
E. Repeat Steps B to D for other cylinder.
NOTE
•
All engines should be checked upon disassembly for incorrect piston alignment. This applies to those which are receiving new pistons as well as those
being completely rebuilt. Observe pistons for wear spots on sides above top compression ring. If one side near wristpin is worn clean while side opposite
is carboned up, then piston was not running straight and true in cylinder bore. Piston will also generally show diagonal wear pattern on thrust faces of
skirts and possibly signs of connecting rod to wristpin boss contact inside piston.
• We feel that not enough emphasis is given to checking piston alignment in cylinder bore. Proper piston alignment means connecting rods will thrust to
sides less minimizing added stress on pistons, rings, rod bearings, and other related parts.
Installation of cylinders and cylinder heads as assemblies may result in damage to rings and piston assemblies. Improper intake manifold
fit may cause intake air leaks/improper fuel mixture and resultant damage to engine components.
Piston Installation
1. Pistons Series #92-2400, #92-2420, #92-2500, #92-2510, #92-2600, #92-2610, #92-2700, #92-2720 and #92-2730 have offset wristpins and
must be installed with dimple cast in piston dome toward right or cam side of engine.
2. All other pistons series have no special features and can be installed any way the builder desires unless there is a piston to piston clearance
bevel on one skirt thrust face. If there is, this bevel must go towards center of engine.
3. Some pistons series have all of the piston to piston clearance in the rear piston. Install rear piston with notch toward front piston. Make sure
dimple in piston dome is in correct position if piston is offset wristpin type.
4. Check all installations for a minimum of .060" clearance between pistons at bottom of stroke.
6. Check all installations for a minimum of .060" clearance between pistons and flywheels at bottom of stroke. New 45⁄8" stroke stock bore
installations should come with proper piston to flywheel clearance. Replacement pistons may or may not come with adequate clearance.
Compare replacement pistons with ones being replaced and make corrections accordingly.
Wristpin Retainer Installation
1. If wristpin clips are to be used, make sure groove is free of burrs and foreign material.
2. Round wire style clips for 1984-’99 big twin pistons, which are identical to and interchangeable with stock H-D® V2® clips, require a specially
chamfered end wristpin. Install clips using H-D recommended procedure. Special indexing of clip is not necessary. Be sure clip is fully seated
in groove.
3. Tru-Arc style clips should be installed using proper tool. Clips should not be used with wristpins with chamfer on end that is greater than
1⁄64". Install clip with open side facing downward and sharp edge of clip to outside of wristpin hole away from wristpin. Be sure clip is fully
seated in groove.
4. Spiral-Loc style clips are installed by slowly working clip into wristpin hole using thumb nail in a screwing motion. Once entire clip is in hole,
use another wristpin to push clip into groove. Be sure clip is fully seated in groove.
NOTE: Spiral-loc type wristpin retainers must not be used with wristpins with beveled ends.
Figure 3
CAUTION