harley oil pump theary of operation

[muddyfeet]

Working on a 29 model c . I disassembled the oil pump. I see 3 spring loaded plungers. When you increase the throttle the cable releases the lever that keeps the plungers compressed Correct ???
How does this increase the oil supply. I see on the other side of the drum two slots with the exposed springs showing. This pumps the oil as it rotates. Does the released spring increase the volume ?? How much more volume ? Maybe best to leave it on full volume as the speed of the motor will decrease and increase the volume. Your thoughts thanks.

[Steve Slocombe]

Dear Muddyfeet, the little pistons pump the oil and the springs return them. The pistons are in a cylindrical body rotated by the drive cam. It bears against a hinged and hardened swash plate, whose angle is changed by the cable-operated adjuster.. At large throttle openings the plate is more angled, the pistons have more stroke and pump more oil. At idle the plate is more vertical and the pistons pump less. There is a screw at the back of the pump to adjust the idle position. The factory setting of the adjuster plate is marked on the oil pump body and the adjuster, and this is a good place to start. No oil control rings were originally fitted in the engine, so oil consumption was a bit more than the modern pistons often fitted in a rebuild. This means oil will usually build up slowly in the crankcases after rebuild, so the oil pump can be trimmed a tad on the 'less' side of the factory marks. Remember this is not a circulating oil system so the oil flow is very small, say 3 cc per mile. If you worry the oil pump is not working, start the engine with the oil line removed and drip oil into the inlet to watch the level go down.

[muddyfeet]

Thanks that was also my thoght. There are three plungers but only two enter into the slots. On the flap/lever side there is a hole that was caked with crude. It looks like there are fine threads in the hole. Is this a vent hole or is oil goilng to pump out. Then on the other side theres a tiny hole that extends into the chamber where the cap screws on.
Thanks for the info