Harley Davidson Model WLA (motorcycle, solo). Service manual (October, 1943) — page 3

TROUBLE SHOOTING
с. Red Signal Light Continues to Burn After Engine Is Operated Above Idling Speeds

(1) Check oil supply in tank. If light fails to go out after engine is warm, or after 1 minute of operation, further checks must be made to locate trouble, as indication points to faulty engine lubrication system, or fault in signal circuit. Eliminate the signal system first.

(2) Test oil pressure signal switch to panel signal light circuit. Remove wire from oil pressure switch terminal by turning on ignition and light switch and observing red signal light. If light bums, short circuit in wiring exists. If light does not burn, it indicates normal condition, leaving oil pressure switch of the signal circuit to be tested.

(3) Install new oil pressure switch and start engine. If red signal light goes out after engine is operated above idling speeds, it indicates trouble in oil pressure signal switch. If red signal light continues to burn, it indicates trouble in oil feed pump. Replace pump (par. 44),

Excessive Smoke Issues from Exhaust and Oil Spray Issues from Gear Case Breather Outlet. This is an indication that the scavenger pump is not draining engine crankcase and returning oil to tank. With engine running at idle speed, examine oil return in tank. Remove tank oil cap, and with a small flashlight (tactical situation permitting), observe whether or not oil is dripping from 1/8-inch hole in oil return tube. Hole is on under side of tube and is located just back of oil gage rod tube. If observation is poor, place finger over hole and feel for pulsation of oil pressure. If oil does not return to tank, scavenger pump is faulty. Should the crankcase breather valve be incorrectly timed, smoke will issue from the exhaust, but not as noticeably as when scavenger pump is not working. Refer to step e below for this condition.

e. Smoke Issues from Exhaust and Excessive Oil Condition Exists Around Cylinder Exhaust Ports (where exhaust pipes enter cylinders), Engine scavenger pump and crankcase breather valve are one unit, operated by worm gear located behind engine shaft pinion gear. Although scavenger pump is not "timed/' the . breather valve sleeve which drives it must be timed to balance the engine lubricating system. If for any reason the scavenger pump unit is removed from engine base, the breather valve must be retimed (within the gear case) when pump assembly is replaced. Incorrectly timed breather valve will force oil past piston rings, causing some smoke, besides forcing oil out through exhaust ports, causing excessive oily condition around exhaust pipes where they enter cylinder ports.

31. FUEL SYSTEM.

a. Many symptoms which might be attributed to the air-fuel system are, in reality, due to faulty ignition. Before attempting any