Velocette 350 - 500 Manual

SERVICE

Velocettte 350 & 500

discs (93) should not show evidence of overheating and should be perfectly flat. When assembling, use soap to assist installation of rubber cushions (90). GEAR BOX. The transmission gears and shafts can be disassembled after the engine is removed and the generator assembly, primary drive

gear and clutch assembly are removed. The intermediate (gear) cover, shift cam, input shaft, countershaft and associated parts can then be withdrawn from crankcase (Fig. TM3-31). Late transmissions use different parts (66, 67, 73 & 79—Fig. TM3-30), Later parts can be installed in early models, but only if all of these parts are

the late type. The early shift cam (66) can be identified by "T** stamped on cam. The late cam is marked "69" stamped as shown in Fig. TM3-32. The late shift fork (67—Fig. TM3-30) has 7/16-inch diameter boss. The late second gear (73) and third gear (79) are stamped "57". Jumping out of gear can be caused by weak spring (110).

YELOCETfE 350 AND 500CC MODELS 350 Clubman & Scrambler

500 MSS

349 72 86 1

499 86 86 1

0.018-0.023 0.012-0.015

0.018-0.023 0.012-0.015

38

38

0.005 0.006 6 Positive 3.25 x 19 3.25x19 16 18 See Text 4 380

350 Viper 349 72 86 1 0.018-0.023 0.012-0.015

MODEL Displacement—cc Bore—mm Stroke—mm Number of cylinders Plug gap—inch Point gap—inch Ignition timing Degrees BTDC—Full advance Valve Clearance—cold Inlet—inch Exhaust—inch Electrical System Voltage Battery terminal grounded Tire size—front Rear Tire pressure—front Rear Rear chain free play—inch Number of speeds Weight^lbs. (Approx.)

500 Clubman & Scrambler

500 Thruxtron

1

499 86 86 1

499 86 86 1

0.018-0.023 0.012-0,015

0.018-0.023 0.012-0.015

0.018-0.023 0.012-0.015

36

38

38

38

0.006 0.008

0.005 0.005

0.005 0.005

6

6

0.006 0.008

Positive 3.00x21 4.00x21

Positive 3.25x19 3.25x19

Positive 3.25x19 3.25x19

Positive 3.00x21 4.00x21

See Text 4 385

See Text 4 385

See Text 4 404

See Text 4 385

0.006 0.008 6 Positive 3.00x19 3.50x19 22-24 24-29 See Text 4 365

6

16 18

MAINTENANCE SPARK PLUG. Spark plug electrode gap should be 0.018-0.023 inch. The following plugs are recommended. KLG type FE80 or FEIOO, Lodge HLN or 3HLN, Champion N3 or N4. CARBURETOR. Amal carburetors are used on all models. The main jet size listed in the following specifications is considered minimum and should be one or two sizes larger for prolonged full throttle operation. Viper Refer to Fig. VLl-1 Carburetor model 376/56 Mainjet(13) 230 Needlejet(ll) 106 Pilotjet(6) 25 Clip (4) in second groove from top of needle (5). Fig. VL1-1-Expioded view of Amai Monobioc carburetor typicai of that used on some modeis. 1. 2. 3. 4. 5. 6. 7.

Pilot air screw Jet block screw Throttle slide Clip Valve needle Pilotjet Idle stop screw

10. 11. 13. 15. 16. 17. 19.

Jet holder Needle jet Main jet Jetblock Float Inlet valve Primer

Viper Refer to Fig. VLl-1 Carburetor model Mainjet(13) Needlejet(ll) Pilotjet(6)

376/61 270 106 30

500 Venom 499 86 86

16 18

6

Clip (4) in third groove from top of needle (5). Venom Refer to Fig. VLl-1 Carburetor model 389/14 Main jet (13) 260 Needlejet(ll) 106 Pilotjet{6) 30 Clip (4) in second groove from top of needle (5). Venom Refer to Fig. VLl-1 Carburetor model 389/15 Main jet (13) 330 Needlejet(ll) 106 Pilotjet(6) 30 Clip (4) in fourth |p"oove from top of needle (5). MSS Refer to Fig. VLl-1 Carburetor model 376/49 Mainjet(13) 240 Needle jet (11) 105 Pilotjet (6) 25 Clip (4) in third groove from top of needle (5). 129

MOTORCYCLE

Velocette 350 & 500

17 Fig. VL1-2-Exptoded view of Amal carburetor of type used on Clubman and Scrambler models. Refer to Fig. VL1-1 for legend.

Clubman (500cc) Refer to Fig. VLl-2 Carburetor model 10TT9 Choke bore 1 3/16 inch Mainjet (13) 370 Needle jet (11) 109 Throttle slide (3) No.4 Clip (4) should be in third groove from top of needle (5). Pilot adjusting screw (1) initial setting lV^ turns open Scrambler (500cc) Refer to Fig. VLl-2 Carburetor model 10TT9 Choke bore 13/16 inch Mainjet(13) 390 Needlejet(ll) 109 Throttle slide (3) No. 7 Clip (4) should be in third groove from top of needle (5). Pilot adjusting screw (1) initial setting lV^ turns open Clubman (350cc) Refer to Fig. VLl-2 Carburetor model TT9 Choke bore 11/16 inch Mainjet (13) 360 Needlejet(ll) 109 Throttle slide (3) No. 7 Cl^p (4) should be in fourth groove from top of needle (5). Pilot adjusting screw (1) initial setting lVfe turns open Scrambler (350cc) Refer to Fig. VLl-2 Carburetor model TT9 Choke bore 11/16 Mainjet (13) 340 Needle jet (11) 109 Throttle slide (3) No. 4 Clip (4) in third groove from top of needle (5). Pilot adjusting screw (1) initial setting i ^ turns open 130

Thruxton Refer to Fig. VLl-3 Carburetor model 5GP2 Mainjet (13) 280 Needlejet(ll) 109 Throttle slide (3) No. 4 Pilot jet (6) 25 Starting jet (8) 125 Clip (4) should be in fourth groove from top of needle (5). Idle mixture is adjusted by turning pilot air adjusting screw (1—Fig. VLl1, VLl-2 or VLl-3), idle speed is adjusted at stop screw (7). On models with GP carburetors (Fig. VLl-3), the fuel level should be at mark (line—Fig. VLl-4) on side of float bowl 0.640 inch below gasket surface of float bowl. When mounting the float chamber, turn the mounting sjtud nuts (N) until the line on float chamber (fuel level) is exactly in line with bottom of circle on the air jet plug as shown in Fig. VLl-4. IGNITION AND ELECTRICAL, Ignition point gap should be 0.0120.015 inch. Full advanced ignition timing should occur 38 degrees BTDC

Fig. VL1-4-The fuel level line marked on float chamber should be exactly in line with bottom of circle on the air jet plug as shown. Adjustment Is accomplished at nuts (N). If float chamber Is too high or too low, the fuel-air ratio will be affected.

-24

Fig. VL1-3-Explod0d view of Amal QP carburetor and float boiW usBd on Thruxton models. N. 1. 3. 4. 5. 6.

Nuts Pilot air screw Throttle slide Clip Valve needle Pilotjet

8. 10. 11. 12. 13. 14.

Startine air valve Jet holder Needle jet Airjet Mainjet Airjet plug

15. 16. 17. 19. 20.

Jet block Float Inlet valve Primer Float bowl gasket surface

21. 22. 23. 24. 25.

Float pivot Flexible mount Mounting stud Fuel inlet baiuo bolt Washer

SERVICE on compression stroke for all models except MSS. On MSS models, the ignition breaker points should just open then the crankshaft is 36 degrees BTDC on compression stroke. Make certain that ignition timing is checked at full advanced position. On models with automatic (centrifugal) advance, weights can be wedged out when checking timing. Ignition timing can be checked after removing the timing gear cover. A degree wheel can be attached to the crankshaft. To change the timing, turn the crankshaft to correct timing position and loosen the retaining nut in the middle of the ignition drive gear. NOTE: Loosening the nut will pull gear from the tapered end of magneto shaft. Turn the ignition breaker points assembly until the points just open, then retighten gear retaining nut and recheck timing. VALVE SYSTEM. Inlet and exhaust valves are actuated by a camshaft located on the right side of the crankcase, via rocker type cam follers, push rods and rocker arms. Valve clearance should he adjusted with engine cold. To check valve clearance, remove the cover from right side of rocker box. Turn the crankshaft until the inlet push rod (IN—Fig. VLl-6) moves up then back down. When the inlet valve just closes, the exhaust valve clearance can be checked as shown. To check inlet valve clearance, turn the crankshaft 240 degrees until the exhaust valve just begins to open (push rod EX—Fig. VL1-6* starts to move up) then measure clearance between top end and push rod. Valve clearance should be 0.005 inch for hoth valves on Viper, Venom and MSS models. Clearance for Clubman, Scrambler and Thruxton should be 0.006 inch for inlet, 0.008 inch for exhaust. LUBRICATION. The engine is lubricated hy approximately 2 quarts of SAE 40 oil above 60°F. or SAE 30 oil below 60°F. Engine oil should he changed at least every 2000 miles. When the oil is drained from the reservoir, the suction filter at bottom (right crankcase half) of engine should he removed and cleaned. Oil should be

Fig. VL1-6-Refer to text when adjusting vaive dearance (C) between end (4) and push rod (S). Inlet push rod (IN) Is toward cyiinder and exhaust (EX) is toward outside. 1. 2. 3. 4. 5. 6. 7.

A4ju8ting screw Locknut Rocker arm End Push rod Cam follower Camshaft

Velocette 350 & 500

5 4 2

1

Fig. VL1-9-The transmission ott shoutd be maintained at ievei of piug (L). Refer~to text for adjusting the primary chain. D. Drain plug

F. Filler plug

L. Level plug

oil. If the oil tube (6) is allowed to drain, make certain that tube is filled before starting engine. The primary chain case and gear box are lubricated hy SAE 40 engine oil. Capacity of the Fig. VL1-8-Expioded view of the oil tank and res- chain case is approximately Vs pint. ervoir assembly. Make certain that oil suction Capacity of the gear box is 1.2 pints tube (6) is full of olt before starting engine after and oil should be maintained at level of servicing. plug (L—Fig. VLl-9). Oil is filled 1. Drain p plug 8. Stud g through hole for plug (F). nd check c 9. Center tube 2. Screen and 10. Lower plate valve seat CLUTCH CONTROLS. The clutch 11. Lower gasket 3. Check valve ball 12. Oil tank is provided with two adjustment points. 4. Check valve spring 13. Filter 5. Adaptor The clutch cahle should have 1/8-3/16 14. Top gasket 6. Suction tube 15. Top plate 7. Return tube inch free play and can be adjusted at the cable adjuster (1—Fig. VLl-11) in maintained at iy2 inches from the top the middle of the cable. If the clutch of the oil tank filler neck. The oil tank slips or does not disengage, proceed as filter (13—Fig. VLl-8) should be re- follows: Turn the clutch cable adjuster newed every 10,000 miles. If oil drains (1) all the way in and disconnect cable from the reservoir (tank) into the from the hand levijr. Open the throttle crankcase, the check valve (3) is and starting air ccmtrols completely, leaking and should be reseated or re- shift transmission to neutral and press newed. kick starter pedal against engine comOil circulation can be checked after pression. removing the oil tank filler cap. If oil is If the clutch slips, remove the front not circulating back to the tank, make section of the rear chain guard. Insert certain that suction tube (6) is full of special tool (part number KA62/2) through one of the holes in the output sprocket and into a notch in clutch spring holder (C—Fig. VLl-11). Turn the rear wheel in normal (forward) direction which will move the sprocket and clutch spring holder in direction (T—Fig. VLl-12) until all slippage is removed. Connect the clutch cable and turn adjuster (1—Fig. VLl-11) until cable has V8-3/16 inch free play. If the clutch will not disengage, insert special tool as shown in Fig. VLl12 and turn rear wheel, sprocket and clutch spring holder in direction (L). DRIVE CHAINS. The primary chain should have l^ inch free play at inspection hole in primary chain cover at the tightest point. To adjust loosen

2 13

131

MOTORCYCLE

Velocette 350 & 500

2

C. Clutch spring holder 1. Cable a((juster 2. Cam lever 3. Rod 4. Thrust cup 5. Thrust bearing and races 6. Thrust pins 7. Back plate 8. Front plate

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Drain plug Filler plug Oil seal Bushing Snap ring Damper bushing Bushing Snap ring Damper valve Damper piston Washer Lockwasher Nut Damper retaining screw

8

Fig. VL1-11 "Drawing of the dutch operating linkage. Refer to text for adjustment

mounting screws (1 & 2—Fig. VLl-9) and the third screw under the transmission. Turn the adjusting nuts (4 & 5) to move the transmission as required to set the correct chain free play, then tighten the three mounting screws. If the primary chain tension is adjusted, the rear chain should also be adjusted. The rear chain free play should be ^ inch when the rear shock absorbers are compressed until the mounting screws are IVA inches between centers. The rear chain free play can be adjusted with the rear wheel off of the ground. With motorcycle on the center stand and rear wheel free, rear chain should have lVi inch free play. SUSPENSION. Each front suspension unit on Viper, Venom and MSS models should contain 7Ice of SAE 20 engine oil. On Scrambler, Clubman and Thruxton models, each front suspension unit should contain 120cc of SAE 20 oil. The front suspension should be drained at plug (1—Fig. yLl-14) and filled at plug (2) with new oil every 10,000 miles. The rear suspension units are adjustable for varying load and riding condition. With top mount in the forward

Fig. VL1-12-Clutch adjustment Is accomplished using special tool as shown. Sprocket is shown partially cut away. The clutch spring holder is shown at (C).

132

position (S—Fig. VLl-15), suspension is soft. The top mount can be located at any position in the slot and the rear most position (F) is firm. NOTE: Make certain that both suspension units are in exactly the same position.

REPAIRS CYLINDER HEAD AND VALVES. Remove the carburetor, fuel tank, spark plug, rocker arm oil tube and cover from right side of rocker box. Turn the crankshaft with kick starter until the inlet push rod (IN—Fig. VLl6) opens (moves up), then closes (moves down). Remove the rocker box retaining screws and stud nuts. Lift the rocker box slightly and turn around the push rods until it can be lifted straight off of push rods. NOTE: The rocker box may be warped if all retaining screws and stud nuts are not loosened evenly. Remove the exhaust pipe. Remove the rocker drain tube from the cylinder head and push rod tube, then slide the top of push rod tube down into lower part. Lift the push rods out and remove the cylinder head retaining stud nuts. The cylinder head studs are slotted on the end and studs should be removed. The cylinder can now be removed. Face and seat angle for both valves is 45 degrees. Clearance between inlet valve stem and guide should be 0.00125-0.0025 inch. Clearance between exhaust valve stem and guide should be 0.00225-0,0035 inch. If guides are renewed, the cylinder head should be heated in water to 212°F. (100°C) before pressing old guides out or new guides in. New guides should be pressed in from top until valve guide protrudes 11/32 inch above the machined surface as shown at (A—Fig. VLl-16). When assembling, the valve springs (32 & 33—Fig. VLl-17) overlap.

Fig. VL1-14-When assembling the front suspension unit the chamfered side of bushing (6) should be toward top.

Fig. VL1-15-Rear suspension Is adjustable. At front of slot (S) suspension Is soft and at rear (F) Is firm.

SERVICE

Velocette 350 & 500 27

VL1-16~Vatve guides shoutd protrude 11132 Inch above machined surface as shown at (A).

Tighten screws and stud nuts retaining the cylinder head and rocker box evenly to prevent distortion. Make certain that push rods are correctly positioned as shown in Fig. VLl-6. Refer to VALVE SYSTEM paragraphs in the Maintenance section for adjusting valve clearance. PISTON, RINGS AND CYLINDER. The cylinder can be removed without removing engine after removing the cylinder head and positioning piston at bottom of stroke. Ring clearance in groove should be 0.0010.003 inch for compression rings; 0.0027-0.0047 inch for the oil control ring. Refer to the following specifications: four screws. It is necessary to remove Ring end gap— the oil pump assembly and worm gear Compression rings— 350cc 0.010 inch (19—Fig. VLl-17) before removing the Oil control—350cc 0.012 inch crankshaft timing gear (11). The nut Venom—all rings 0.010 inch retaining the oil pump worm gear and MSS—all rings 0.015 inch timing gear to the crankshaft is left All other 500cc models . . . 0.020 inch hand thread. Camshaft bushing (17) should have Standard cylinder bore diameter— 0.001 inch clearance on spindle (15). 350cc models 2.8347 inches 500cc models 3.385 inches Cylinder bore taper or out of round limit 0.008 inch Pistons and rings are available in standard size and oversizes of 0.020 and 0.040 inch. The piston pin should have 0.0007-0,0016 inch clearance in the rod bushing. The oil hole in the top of piston pin bushing should be aligned with hole in top of connecting rod. If bushing is worn or loose in connecting Fig. VL1-18-Expioded view of rod, renew bushing. Connecting rod the crankcase, cyttnder alignment must be checked after in- head and rocker box. Refer stalling the bushing. atso to Ftg. VLl-17. When assembling, the split in piston 1. Timing cover oil jet Timing cover skirt must be toward front. Compres- 3.2. Rocker arm pressure line sion ratio is changed by installing 4. Rocker box drain tube 5. Suction oil filter compression plates (11—Fig. VLl-18) 6. Timing plate 7. Camshaft oil jet of different thicknesses. 8. Push rod tube (lower)

CAMSHAFTS AND TIMING

GEARS. The timing cover (2—Fig. VLl-18) is attached to the right side of engine with 10 screws. When removing, be careful not to warp or burr the cover or sealing surfaces. The timing gear steady plate (6) is attached with

9. 10. 11. 12. 13.

3 2

VL1-17-Exploded view of the crankshaft, camshaft and associated parts. Beiieviite washer (W) Is Instatted between crankcase and cam fottowers. 1. Spring collar 2. Washer 3. Generator pulley t. Shock absorber spring 3. Shock absorber cfrive clutch i3. Primary drive sprocket 7. Shims 3. Roller bearing 9. Roller bearing 10. Shims 11. Crankshaft timing gear 12. Idler gear 13. Bushing U. Idler shaft 15. Camshaft spindle 16. Camshaft 17. Bushing 13. Magneto drive gear and advance assembly 19. Oil pump worm gear 20. Oil pump drive gear 21. Oil pump pressure gears 22. Oil pump return geare 23. Cam followers 24. Push rods 25. End caps 26. Exhaust rocker arm 27. Inlet rocker arm 28. Valve guide 29. Keepers 30. Cap 31. Retainer 32. Valve spring (large loop) 33. Valve spring (small loop) 34. Spring lower adaptor

Push rod tube (upper) Push rod guide plate Cylinder spacer Decompression lever Rocker box

1

2 133

MOTORCYCLE SERVICE

Velocette 350 & 500

Remove the air cleaner, oil tank, generator and front section of the rear chain guard. Disconnect clutch and decompression control cables. Remove the cylinder head steady strap, carburetor and exhaust pipe. Remove the final drive sprocket from the transmission output shaft, support the engine and remove bolts from the engine front and rear mounting plates. Tilt the engine and gear box forward and lift out of frame. Remove the clutch assembly, primary drive shock absorber and the primary drive chain. The gear box can now be unbolted from the rear of crankcase. Remove the engine oil pump, timing gears, cylinder head, cylinder and piston. The connecting rod and crankpin are removed by pressing the crankshaft CONNECTING ROD AND apart. When assembling, crankshaft CRANKSHAFT. To remove the con- eccentricity must not exceed 0.001 inch necting rod and crankshaft, the engine when measured at main bearing surand gear box must be removed from the faces with crankshaft between lathe frame and crankcase halves must be centers. Connecting rod side play should be 0.008 inch. separated.

Idler gear bushing (13) should have 0.0015 inch clearance on spindle (14). End play of idler gear (12) and camshaft (16) should not exceed 0.0015 inch. When assembling, align timing marks as shown at (A & B—Fig. VLl19). Backlash of timing gears can be adjusted by loosening the three screws attaching spindle (14—Fig. VLl-17) to the crankcase, then moving spindle and idler gear (12) toward rear. Refer to preceding paragraphs in Maintenance section for adjusting the ignition timing. When installing cover (2—Fig. VLl-18, leave oil tube (3) loose until engine is started. Tighten the connection to cover after oil begins flowing from the loose connection.

Fig. VL1-19-ViBW of the camshaft timing gears with marks (A & B) aligned.

Fig. VL1-20-Exploded view of the clutch and gear box. Most service can be accompiished without removing the engine and gear box from the fram:

134