S&S Cycle Pistons - Manual (Page 5)

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5- If your piston application uses oil ring support rails, install ring support rail in front piston so that the end gap is toward the rear of the cylinder
(90° from wristpin). Install ring support rail on rear piston so that the end gap is toward front of the cylinder (90° from wristpin). The dimple in
the ring must face down and be installed in the gap above the wrist pin on both pistons. See picture below.
6- Ring Gap Placement
A- Oil ring
1- Expander gap must be in center of thrust face (rear of piston), or 90° from wristpin.
2- Bottom rail gap should be approximately 1.5" or 45° to right of expander gap.
3- Top rail gap should be approximately 1.5" or 45° to left of expander gap.
NOTE: Confirm that ends of expander do not overlap during installation. Properly installed expander will appear larger than piston but will compress
when cylinder installed.
B- Top compression ring gap should be 135° or approximately 41⁄2" to left of oil expander gap.
C- Second compression ring gap should be 135° or approximately 41⁄2" to right of oil expander gap.
*NOTE: Fit wristpins at .0007" to .001".
ENGINE BREAK-IN PROCEDURE
NOTES:
•
S&S® engines are designed for high performance and as such are not as tolerant of inadequate break-in. Correct break-in will assure longer engine life
and will prevent unnecessary engine damage. Engine damage caused by improper break-in is not covered under the S&S warranty.
•
If new pistons have not been installed, only steps A, B, and C are required.
•
If new pistons have been installed, all break in steps are required.
A- Initial start up. Run engine approximately one minute at 1250-1750 rpm. DO NOT crack throttle or subject to any loads during this period
as head gaskets are susceptible to failure at this time. During this time check to see that oil pressure is normal, that oil is returning to the oil
tank, and that no leaks exist.
B- Shut off engine and thoroughly check for any leaks or other problems. Let engine cool to the touch
C- After engine has cooled, start up again and allow the motor to build some heat. Engine should be run no longer than three to four minutes.
When the cylinders become warm/hot to the touch (approximately 150°) shut the motor down and let it cool to room temp. Follow the
same cautions as for the initial start-up, and continue to watch for problems.
D- Repeat this procedure 3 or 4 times. Each successive time it should take slightly longer to warm up and you can increase the temp slightly
each time (+10°). You can be more liberal each time with the rpm, gently vary rpm continuously from idle up to 2500 rpm in the final cycle.
Don’t be too concerned with final carb settings at this time because idle speed and mixture cannot be correctly set until the motor reaches
full operating temperature. The motor should not reach that temperature during these cycles. Do not allow engine temperature to become
excessive. After the motor has cooled to room temperature for the final time you are ready to start the 500 mile engine break-in process.
E- The first 50 miles are most critical for new rings and piston break-in. Engine damage is most likely to occur during this period. Keep heat
down by not exceeding 2500 rpm. Avoid lugging the motor, riding in hot weather or in traffic. Vary the engine speed. Do not lug the engine.
We recommend changing the oil at 50 miles.
F- The next 500 miles should be spent running engine no faster than 3500 rpm or 60 mph. Avoid continuous steady speeds, and do not lug
the engine. Vary engine rpm. We recommend changing the oil again at 500 miles.
Lugging or running engine prematurely at sustained high rpm may result in damage to pistons and other engine components. S&S®
voids its guarantee if engine is not broken in properly.
CAUTION