P

Parts Catalog

Sold separately from the Service Manual by the MoCo specifically for your year bike. It contains blow-up diagrams of parts/ part numbers and is good for ordering/ cross referencing parts, or identifying missing parts.

Piston Slap

A condition where the piston, cylinder or both are worn out of round and are loose fitting.
This allows the piston to 'slap' against the cylinder walls from front to rear as it travels up and down the cylinder. 1)

Pour Point

Indicates the fluidity of oil on low temperature. It’s the lowest temperature off which an oil can flow.2)

Pre-Ignition

A condition in which the fuel/air mixture ignites before the spark plug fires. This is often caused by carbon buildup in the cylinders/ top of pistons which can allow the engine to seem to “run on”,3)hot fuel or the lubricant buildup in the combustion chamber. It reduces engine power and can damage the engine.4)

Pre-load (bolt-fastener)

Bolt pre-load is basically the spring pressure that holds materials together that is applied by the bolt. Once a bolt is tight, it doesn’t turn any longer. You have a mating surface (underside of the bolt) touching the mating surface it is on. Any further tightening will stretch the bolt in a circular motion that adds clamp force to the mating surfaces. The amount of clamp force needed depends on the materials and application. All bolts have a spring pressure limit called a point of “yield”.

Pre-load (suspension)

The amount of spring compression applied to the shocks when they are in the unload state.

Primary Drive

The ratio between the engine and the transmission, reflects number of engine revolutions to turn the transmission sprocket one full turn. Main components are the sprockets on the engine/ transmission clutch basket and the drive chain between them

PS (Pferdestärke)

A German interpretation of BHP (Brake Horsepower) or Engine Power Output

PSI

Abbreviation for Pounds (of force) per Square Inch. An imperial measurement of tire or cylinder pressure.

Pulse Secondary Air Injection

Process of routing fresh air into the exhaust system to burn off excess gases

Pumpability

A low-temperature property of oil, which determines to what extent the oil is capable of flowing to the pump on low temperatures.5)




1)
86 HD XL FSM pg 3-10
3)
Haynes Sportster manual 1970-2010 pg REF*51
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