| Paragraph | |
|---|---|
| Introduction | 28 |
| Engine | 29 |
| Engine lubricating system | 30 |
| Fuel system | 31 |
| Ignition system | 32 |
| Generating system | 33 |
| Electrical system | 34 |
| Transmission and clutch | 35 |
| Wheels and chains | 36 |
| Brakes | 37 |
| Steering | 38 |
a. Trouble shooting for the entire vehicle is given in this section. The engine trouble shooting paragraph traces trouble to a system affecting engine performance: for example, fuel or ignition. To trace trouble to one or more defective components of a system, it is necessary to refer to the pertinent paragraph of this section when the defective system or systems have been located in the engine trouble shooting paragraph.
b. The material given in this section applies to the operation of the vehicle under normal conditions. If extreme conditions of temperature occur, it is assumed the operator of the vehicle has prepared his vehicle for use for the conditions encountered.
a. Instruction. This subparagraph traces troubles to a system affecting engine performance. Step b below gives simple engine tests to determine the mechanical condition of the engine. References in step b refer to step c for engine mechanical troubles, or to pertinent paragraphs in this section for system troubles, or when a test indicates a special unit is faulty, to the pertinent paragraph in this manual.
(1) Engine Does Not Turn Over When Foot Starter Is Operated.
(a) Clutch slipping. Check adjustment (par. 48).
(b) Sheared engine sprocket key. Replace (par. 65).
(c) Starter clutch stuck by congealed oil. Free starter clutch. Use proper grade of oil.
(d) Starter clutch worn. Refer to maintenance personnel.
(e) Engine locked (seized). Refer to organization mechanic.
(2) Engine Turns Over When Cranked but Does Not Start.
(a) Fuel supply valve closed. Open valve.
(b) Empty fuel tank. Fill tank.
(c) Fuel system faulty. Refer to paragraph 31.
(d) Ignition system faulty. Refer to paragraph 32.
(e) Battery weak or dead. Refer to paragraph 34.
(f) Insufficient compression. Refer to step b, below.
(3) Weak Compression. Refer to step b below for test.
(a) Improper valve tappet adjustment. Adjust (par. 43).
(b) Valves sticking. Use dry‐cleaning solvent to free valve stems in guides.
(c) Faulty lubrication. Refer to paragraph 20.
(d) Loose cylinder head bolts and/or faulty gasket. Tighten head bolts or replace gasket (par. 41).
(4) Overheating.
(a) Faulty fuel system. Refer to paragraph 31.
(b) Dirt on cylinders. Clean fins on cylinder, especially the fins on cylinder head.
(c) Defective lubrication system. Refer to paragraph 30.
(d) Defective ignition system. Refer to paragraph 32.
(e) Idling engine without having vehicle in motion. Do not idle engine longer than 1 minute.
(f) Valve tappet adjustment incorrect. Refer to step b (1) below for test, to paragraph 43 for adjustment.
(g) Drive chains too tight. Adjust (pars. 59 and 60).
(h) Excessive carbon deposits. Refer to organization mechanic.
(5) Lack of Power.
(a) Defective fuel system. Refer to paragraph 31.
(b) Defective ignition system. Refer to paragraph 32.
(c) Overheating. Refer to step (4) above.
(d) Defective lubricating system. Refer to paragraph 30.
(e) Poor compression. Refer to step (3) above.
(f) Drive chains too tight. Adjust (pars. 59 and 60).
(g) Brakes dragging. Adjust (pars. 96 and 97).
(6) Popping and Spitting Through Carburetor.
(a) Water in fuel. Water may be present in fuel tank and carburetor. Drain and refill fuel tank and carburetor bowl.
(b) Incorrect valve tappet adjustment or sticky valves. Test (step b (1) below). Adjust tappets (par. 43). (c) Defective ignition system. Refer to paragraph 32.
(d) Defective fuel system. Refer to paragraph 31.
(e) Weak and/or broken valve springs. Refer to higher authority.
(7) Spark Knock.
(a) Defective ignition system. Refer to paragraph 32.
(b) Excessive carbon deposits. Refer to step b (2) below.
(c) Defective fuel system. Refer to paragraph 31.
(d) Defective lubrication system. Refer to paragraph 30.
(8) Pounding and Excessive Metallic Noise.
(a) Front drive chain too loose. Refer to paragraph 36.
(b) Engine sprocket loose on shaft.
(c) Excessively loose valve tappets. Adjust (par. 43).
(d) Engine mounting bolts loose. Tighten.
(e) Transmission mounting stud nuts loose. Tighten (par. 60).
(f) Spark timing incorrect. Adjust.
(g) Internal parts of engine worn or broken. Notify organization mechanic.
b. Tests to Determine Mechanical Condition of Engine.
(1) Rings and Valves. This is a simple compression test. If possible, make this test with the engine warm. Ignition switch must be off. Crank engine slowly, placing entire weight of body on starter crank. Engine compression should sustain the weight of an average size rider several seconds before crank passes through complete range of its travel. If engine offers little resistance to starter crank in testing either or both cylinders, it is an indication that compression is not adequate in one or both cylinders. No clearance or insufficient clearance at valve tappets; valves sticking in guides; valves seating poorly; cylinder heads leaking; spark plugs loose in heads; piston rings badly worn and/or broken; cylinder and pistons badly worn, or lack of lubrication could cause the above condition. Make external checks first: See that oil is in tank, that spark plugs are tight, and examine around cylinder heads for signs of leaking oil deposits. In extremely cold weather, resistance to the starter crank is increased by “stiff” oil in engine and transmission. Therefore, do not mistake this condition to indicate actual engine compression.
(2) Abnormal Engine Noise. Owing to constructional design of the motorcycle, correct adjustment of the several units and components is necessary for smooth and normally quiet engine operation. Many motorcycles have been “deadlined” and engines exchanged because simple tune‐up service and correct adjustment of components have been neglected. Rough, jerky, and noisy engine action at low speed riding is usually caused by excessively loose front and rear drive chains, or by a transmission being loose in its frame mounting. Fast idling of engine with the front drive chain too loose, may give the false impression that the engine bearings and pistons need replacement service. Engine sprocket loose on its shaft will cause a pounding noise similar to that of badly worn engine bearings. If front drive chain is too tight, or engine sprocket and chain are badly worn, a grinding noise results, seeming to come from the engine. Excessively loose valve tappets will cause abnormal metallic noise in the valve timing gear train and engine crankcase. Spark advanced too far will cause rough engine performance at low speeds as well as spark knock, pounding, and overheating. Engine pounding and rough operation with consequent noise, result from loose mounting bolts. Generator mounted to give insufficient gear‐tooth clearance will cause “howl” in gear case.
a. Action of the oil feed pump is indicated by the red signal light located in right side of instrument panel. (Red signal light is normally grounded by the oil pressure switch. When oil pump pressure is built up several pounds, diaphragm opens the signal light circuit.) Action of the scavenger (oil return) pump is indicated (engine running) by oil dripping from 1⁄8–inch hole in oil return tube (large tube) inside oil tank, just back of oil gage rod (dip stick) tube. Since the oil feed pump and scavenger pump are separate units, operated individually, it is possible (due to faulty unit) for either to function alone, thus affecting engine oil pressure and return of oil to the tank. Action of the vent pipe (small pipe) located within the oil tank is of a “breather” nature; its function not being indicated in any manner. Before attempting to diagnose trouble in engine lubricating system, rider must be familiar with and understand indications by instrument panel signal lights (par. 7 f).
b. Red Signal Light Fails to Burn When Ignition and Light Switch is Turned On.
(1) Check other lights to determine if battery is “up” and that switch and wiring connections between battery and switch are in good order. See that wire connection is secure and screw is tight on oil pressure switch terminal. Failure of light to burn after these checks indicates that either the lamp is burned out or oil pressure switch is faulty.
(2) Test to eliminate the oil pressure switch by removing wire from switch terminal; ground wire on switch body and note if red light burns with ignition and light switch in “ON” position. If light burns, it indicates that oil pressure switch is faulty, and must be replaced. If light does not burn in making this test, it indicates that lamp is burned out. Remove panel cover (par. 119) and replace lamp.
c. 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 burns, 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).
d. 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.
a. Many symptoms which might be attributed to the air‐fuel system are, in reality, due to faulty ignition. Before attempting any but the obviously required adjustments, check the ignition system thoroughly. Gasoline tank supply valve is a dual purpose valve, and its operation is explained in paragraph 5 b.
b. Shut off gasoline supply valve. Disconnect fuel line at strainer, open valve, and observe free flow of fuel from pipe. If line is plugged, remove, clean out, and replace.
c. Remove, disassemble, clean, and install fuel strainer (par. 72).
d. Hard Starting, Spitting, and Misfiring Caused by Water in Fuel. Remove drain screw from carburetor bowl, drain bowl, and replace screw. Take care not to cross drain screw threads when replacing. If there is still evidence of water, dirt, or other foreign matter after bowl is drained, replace carburetor (pars. 70 and 71). Remove air cleaner oil cup and inspect for evidence of water in oil. Drain, clean, refill to correct level mark, and replace cup. Should above procedure fail to eliminate trouble, drain fuel tank by removing drain plug located under tank in forward position. Replace drain plug and refill tank with fuel.
e. Hard Starting, or Missing at Idling and Low Speeds. Carburetor low speed circuit in need of adjustment (par. 68). Carburetor high speed circuit is controlled by a fixed jet.
f. Impossible to Obtain Satisfactory Carburetor Adjustment: Lean Spot Between Idling and Up to 30 Miles per Hour Speeds. Carburetors in service for some time become dirty and crust forms in the throttle barrel, making satisfactory low speed adjustment difficult, if not impossible. Replace carburetor (pars. 70 and 71).
g. Fuel Leaking from Carburetor. Evidence of dirt in float valve, incorrect float level, or faulty float. Replace carburetor (pars. 70 and 71).
h. Difficult Starting, Fuel Mixture Too Rich. Air cleaner oil cup overfilled, or cleaner elements exceptionally dirty, choking off adequate air supply to carburetor. Check the oil cup level. If oil cup level is correct, remove, clean, and install cleaner elements (par. 76).
a. When checking ignition system for trouble, make the most obvious and simple checks first. For example: Turn on ignition and light switch, observe lights to ascertain battery current supply; then check to see that current is reaching spark coil, circuit breaker, etc. Faulty spark plugs are responsible for the great majority of engine ignition troubles. There is no service for spark plugs other than sandblast cleaning and correct adjustment of electrodes. Questionable spark plugs must be replaced (par. 83).
b. Remedy all poor connections in ignition wiring system ( fig. 48).
c. Remove circuit breaker cover, operate engine with starter pedal, and observe opening and closing of circuit breaker points. Correct point gap when breaker lever fiber is on highest point of cam is 0.022 inch. For adjustment refer to paragraph 84.
d. Testing for High Tension Spark. Spark at plug gaps depends upon condition and operation of circuit breaker points, condition of condenser, and condition of spark coil and high‐tension cables. Testing the ignition system is best done by means of elimination, testing each unit by replacement until trouble is located; then replacing serviceable units which were removed.
(1) Remove spark plug cable terminal from either plug, leaving other cable and plug connected (to effect ground return of high‐tension current); turn engine until circuit breaker points are closed; turn ignition and light switch on; hold high tension cable terminal ¼ inch from cylinder; open and close circuit breaker points with finger and observe spark jump at gap. If spark jumps gap, it indicates ignition primary and secondary circuits are complete.
(2) No spark at high‐tension gap calls for testing of primary and secondary circuits. Turn engine until breaker points are held open; hold cable end ¼ inch from cylinder; turn ignition switch on and with the bit of a screwdriver, make a good ground connection between breaker movable (lever) point, and the ground. If a good spark is obtained at high‐tension cable terminal gap when ground connection made by screwdriver is broken, clean or replace faulty breaker points (par. 84).
(3) If circuit breaker points are in good condition, but no spark (or a very weak spark) occurs at high‐tension gap, replace condenser (par. 85) and repeat test under step (1) above. If replacement of condenser does not remedy trouble, replace spark coil (par. 89).
(4) If tests made under steps d (1), (2), and (3) above show ignition system to be in good order (no units having been replaced), and ignition trouble still exists, it means that breaker points, condenser, and spark coil must be replaced with new units and engine road test made with each replacement until trouble has been located and remedied.
e. Ignition System Tests Satisfactory but Engine Starts Hard, Overheats or Misses. Clearly an indication that spark plugs are faulty. Remove spark plugs, clean with sandblast, regap points between 0.028 inch to 0.030 inch and reinstall. Replace defective plugs with new ones of correct (No. 2) heat range (par. 83).
f. Engine Misses After Warm‐up, or When Quite Hot. Replacement of spark plugs should remedy this trouble. If it does not, then either the condenser or spark coil is at fault. Replace condenser first (par. 85). If new condenser fails to correct trouble, replace spark coil (par. 89).
a. Panel Green Signal Light Continues to Burn Above 20 Miles per Hour. Correct faulty wiring and connections between battery and generator. Refer to figure 55. Inspect condition of relay and, if necessary, replace (par. 95). Inspect brushes and commutator of generator. Clean commutator if necessary (par. 91). If brushes are sticking in holders or badly worn, replace generator (pars. 93 and 94).
b. Generator Output Fails to Keep Battery Charged Although Green Signal Light Behavior Is Satisfactory. Test battery: if it will not hold charge, or is defective, replace (par. 113). If the machine is used most of the time for night operation, have a higher echelon increase the generating charging rate. Inspect brushes and commutator of generator. Clean commutator if necessary (par. 91). If brushes are badly worn or sticking in holders, replace generator (pars. 93 and 94).
a. Panel Lamps Do Not Light When Switch Is Turned On. Examine each lamp and if burned out, replace (par. 120). Examine battery; if discharged, replace (par. 113). Remedy defective wiring and connections (fig. 71). Test light switch: if defective, replace (par. 116). Test blackout light switch (in lamp body): if defective, replace lamp (par. 114).
b. Lights Burn Dim but Brighten Up Considerably When Engine Is Accelerated. Test battery with hydrometer. If it is not fully charged, replace (par. 113). Remedy defective wiring, connections, and switches in circuit (fig. 73). If the battery runs down again after a short period of operation, have the generator output increased (refer to a higher echelon).
c. Lights Exceed Normal Brilliancy When Accelerating Engine. Examine battery: if defective, replace (par. 113). Remedy faulty wiring and connections (fig. 73). Do not forget the ground connection of the lamp body.
d. Blackout Stop Lamp and/or Service Stop Lamp Fail to Light. If the unit is burned out, replace it (par. 115). If the brake pedal is not operating switch, remedy the faulty operation. Remedy all faulty wiring and connections (fig. 73).
e. Horn Does Not Sound When Ignition and Light Switch Is Turned On and Horn Button Is Pressed. Test battery by turning on lights. If lights are dim, replace battery (par. 113). Remedy defective wiring and connections (fig. 73). If the horn does not respond to adjustment, replace (par. 117).
a. Need for attention to clutch and controls is indicated by clutch slipping under load or dragging (transmission gears will shift hard and clash) when in disengaged position. In either case, the first thing to be checked is adjustment of controls; this being the attention usually needed. Indication that gear shifter controls are in need of adjustment is when transmission gears “jump” out of engagement when accelerating vehicle or when under heavy pull. CAUTION: This warning must not be disregarded.
(1) Clutch Slips When Fully Engaged. Adjust clutch control (par. 48). Adjust clutch spring tension (par. 48). If the clutch still slips, replace either the disks, springs, or both (par. 48).
(2) Clutch Drags When Fully Disengaged. Adjust control (par. 48). Adjust spring tension (par. 48).
(3) Clutch Rattles When in Disengaged Position, Engine Idling. In this case, the clutch probably was not properly assembled. Refer to paragraph 51 a.
(4) Transmission “Jumps” Out of Gear Upon Accelerating Vehicle, or When Under Heavy Pull. Adjust shifter lever control linkage (par. 54).
(5) Transmission Gears Shift Hard or Clash When Clutch is Fully Disengaged. Adjust clutch control linkage and spring tension (par. 48). Make sure the transmission mounting bolts and units are tight (pars. 57 and 58). Drain and fill transmission with correct lubricant (fig. 10). If the above methods fail to cure the symptom, refer to a higher authority.
a. Transmission Countershaft and Rear Wheel Sprockets Show Excessive Wear on One Side of Teeth. Adjust the position of the rear wheel axle to aline the rear wheel sprocket with the transmission sprocket (par. 60). If they cannot be alined, the frame is out of alinement, and the trouble must be referred to a higher authority.
b. Chains Produce Grinding Noise with Engine Idling and Vehicle on Rear Stand. If either chain is adjusted too tight, adjust to proper tension (pars. 59 and 60). Examine both chains for presence of dirt and grit. If dirty, clean and lubricate them (par. 20 c (10)). If either chain is dry, adjust chain oilers (par. 61). Badly worn chains and sprockets will cause this symptom; the worn parts must be replaced (pars. 62 and 63).
c. Front Chain Dry and/or Red (Rusty) in Appearance. The chain in this condition has not been receiving enough lubrication. Adjust chain oiler (par. 61). If the chain is damaged from lack of oil, replace (par. 62).
d. Rough or Jerky Vehicle Operation at Low Speed. Chains are too loose. Adjust (pars. 59 and 60).
e. Excessive Side Play at Rim of Front Wheel. Adjust bearing cones (par. 126). If the cones and or hub races are badly worn, replace wheel (par. 125).
f. Front Wheel Spinning Test Produces Grinding, Grating Noise (not in brake). The wheel bearings are defective. Replace wheel (par. 125).
g. Rear Wheel Has Excessive Side Play at Rim of Wheel. The hub bearings are defective. Replace wheel (par. 127).
h. Rear Wheel Has Side Play in Excess of 0.010 inch on Axle. The thrust washers of hub are worn or damaged. Replace wheel (par. 127).
i. Rear Wheel Spinning Test Produces Grinding, Grating Noise (chain removed). Tighten wheel mounting screws. If this does not correct noise, replace wheel (par. 127).
a. Rear Brake Does Not Hold When Foot Pedal Is Depressed. If the brake linings are wet, operate the vehicle and apply a slight pressure to the brake pedal to dry out linings. After drying the linings adjust brake rod length (par. 96 b). If the brake operating lever stands ahead of the vertical position with brake applied, or the brake does not hold, replace the defective brake shoes (par. 96).
b. Rear Brake Squeaks or Chatters When Used. Tighten side plate sleeve nut, if it is loose. Adjust shoe position (par. 96). If the operating camshaft and/or side cover bearing is worn, replace the assembly (par. 96). If the brake shoe spring is defective, replace (par. 96). If the lining on the brake shoes is loose, worn, or defective, replace shoes (par. 96). If the brake drum is worn or damaged, replace the brake drum and sprocket assembly (par. 96).
c. Rear Brake Drags (vehicle on rear stand). Adjust linkage (par. 96). If it still drags, equalize shoe assemblies, and adjust linkage (par. 96).
d. Front Brake Does Not Hold When Hand Lever Is Operated. Adjust brake control (par. 97). If brakes are wet, operate vehicle a short distance with slight pressure on brake lever to dry out linings. If brake does not hold, replace shoes (par. 97).
e. Front Brake Drags. Adjust control linkage (par. 97). If brake still drags, equalize shoes and readjust control linkage (par. 97).
f. Front Brake Action Rough and/or Chatters. Adjust control linkage assembly (par. 97). If malfunction continues, examine brake shoes, shoe spring, camshaft bearing and side cover bearing. Replace any defective parts or assemblies (par. 97).
a. Motorcycle Pulls to One Side. Inspect and correct alinement of rear wheel (par. 60). If the front forks are bent or twisted, replace (par. 98). If trouble persists, refer to higher authority.
b. Motorcycle Weaves from Side to Side. Adjust steering damper to suit speed and road conditions. If this fails, inflate tires to correct pressure. Make sure rear wheel mounting screws are tight. If the steering head bearings are too tight, weaving will result. Check the steering head bearings (par. 98), and adjust if necessary.
c. Motorcycle Shimmies at High Speed. Inflate tires to correct pressure. Adjust steering damper to suit speed and road conditions. If the tire tread is unevenly worn, and shifting tires does not correct the condition, replace the defective casings. Make sure the axle nuts are tight. If the rocker plate studs and bushings are badly worn, or the fork springs are broken, replace (par. 98).