S&S Cycle Sidewinder 3 5⁄8 Big Bore Cylinders for Harley-Davidson Sportster Models—1986–2003 - Manual (Page 17)

17
Unwarranted gasoline leaking by fuel inlet needle may flood engine causing damage to components.
• If throttle does not return to fully closed position when released, it may inadvertently stick open possibly causing loss of control of
motorcycle and personal injury to you or others.
• Unwarranted gasoline leaks at fuel line connections and/or past inlet needle may flood engine and overflow on surrounding area
creating fire hazard.
14. Engine Break-In Procedure
A. Upon initial start-up, quickly check to make sure oil pressure is normal and no leaks exist. With minimal load on engine, ride motorcycle
at low speeds until cylinder head temperature reaches about 250°. Do not crack throttle or subject engine to any heavy load during this
period as head gaskets are susceptible to failure until heat build-up is completed. Heat build-up is necessary to cause heads and cylinders
to expand and seal. Improper initial engine start-up and break-in procedure may cause head gasket failure.
Do not allow engine temperature to become excessive as permanent engine damage may result.
B. First 50 miles are most critical for new rings and piston break-in. Most engine damage will initially occur during this period. Keep heat
down by not exceeding 2500 RPM. Vary speed. Do not lug engine.
C. Next 500 miles should be spent running engine no faster than 3500 RPM or about 50-55 mph. Do not lug engine and continue to vary
speed.
Lugging or running engine prematurely at high RPMs may result in damage to pistons and/or other engine components. S&S® voids its
guarantee if engine is not broken in properly.
D. For balance of first 1000 miles, speed can be run up to 60 to 70. Continue to run engine at all different speeds including lower 40–45 mph
ranges.
E. 1000 to 2000 miles—basically same procedures as before. You can be a little more liberal with RPM range. Avoid overheating engine and
putting any hard strain on engine (drag racing, trailer towing, sidecar operation).
G. 2000 miles and up—have fun!
15. PErFOrmaNcE NOTES
Ignition
• Ignition system type—Most S&S engines initially tested on our dyno are equipped with an aftermarket high performance electronic unit. These
systems allow us to bypass the performance parameters (such as the RPM limiter) designed for stock parts and built in to the stock ignition system.
• Spark plugs—Use spark plugs that are compatible with the ignition system. If you are in doubt, most manufacturers can recommend which plugs
they prefer you use with their system. Dual plug installations in S&S Super Stock® heads are not necessary.
• Flywheels—S&S flywheels for Evolution® Sportster® models have timing marks for front and rear cylinders. Both flywheels have timing marks to
accommodate both four speed and five speed engines. The “F” mark is front cylinder 30° advanced (before TDC). The “R” mark is rear cylinder 30°
advanced. When “F” or “R” timing marks are located in the center of the timing hole, the crankshaft is positioned 30° before TDC for that cylinder.
Placing the mark to the rear of the hole, or just entering the hole, advances timing almost 5°. Conversely, if the mark is just leaving the hole, timing
is retarded almost 5°.
• Timing—Tests conducted using S&S Super Stock® heads and modified stock Harley-Davidson® heads showed that best performance was
achieved with the ignition timing set between 30–32° before TDC. We attribute this to the higher compression ratios generally used, improved
flow characteristics and improved overall efficiency. If using stock heads, the higher the compression ratio less advance is generally needed.
Lower compression engines may require more advance. Some experimentation may be required to determine the best timing setting for best
performance. Once the engine is timed and operating, monitor it for excessive heat. Too much heat can mean that timing is set incorrectly and
should be adjusted to prevent engine damage.
Improper ignition timing may cause excessive engine heat which may damage pistons and/or other engine components.
CAUTION
CAUTION
CAUTION
CAUTION
WARNING