BSA D7 175CC BANTAM Workshop Repair Manual

175 c.c. Silver Bantam. 175 c.c. Bantam de luxe. Model D7. INSTRUCTION MANUAL

175 c.c. SILVER BANTAM. Model D7. 175 c.c. BANTAM de luxe. Model D7. B.S.A. MOTOR CYCLES LTD., ARMOURY ROAD, BIRMINGHAM, 11 Telephone: Birmingham, VICtoria 2381 Telegrams and Cables: “SELMOTO,” Birmingham. B.S.A. Motor Cycles Ltd. Reserve the right to alter the designs or any constructional details of their manufacture at any time without giving notice. Printed in England Copyright B.S.A. Co. Ltd. MC 1439-5 I N S T R U C T I O N M A N U A L

This Instruction manual is intended to acquaint the B.S.A. owner with details of the controls, general maintenance and technical data which may be required for normal operation of the machine. It does not contain the information necessary to carry out complete stripping for major overhauls, but if any owner feels competent to carry out this type of work, a service manual and an illustrated spares catalogue for this machine can be obtained from his B.S.A. spares stockist or local dealer. Owners in the British Isles can obtain these publications direct from B.S.A. Motor Cycles Ltd., Service Department, Armoury Road, Birmingham 11. Always quote full engine and frame numbers when ordering these publications. 2

Fig. 1. The Controls (Bantam de luxe) (Silver Bantam similar except in detail) 3

CONTENTS AIR CLEANER . . . . . . . . . . . . . . BRAKES . . . . . . . . . . . . . . . . CARBURETTER . . . . . . . . . . . . . . FRONT CHAIN . . . . . . . . . . . . . . REAR CHAIN . . . . . . . . . . . . . . CLEANING . . . . . . . . . . . . . . CLUTCH . . . . . . . . . . . . . . . . CONTROLS . . . . . . . . . . . . . . CYLINDER HEAD AND BARREL REMOVAL . . . . DRIVING . . . . . . . . . . . . . . . . DECARBONISING . . . . . . . . . . . . ELECTRICAL EQUIPMENT . . . . . . . . . . FORKS . . . . . . . . . . . . . . . . GEARBOX . . . . . . . . . . . . . . . . HUBS . . . . . . . . . . . . . . . . IGNITION TIMING . . . . . . . . . . . . LUBRICATION CHART . . . . . . . . . . LUBRICATION (ENGINE) . . . . . . . . . . ROUTINE MAINTENANCE . . . . . . . . . . REAR SUSPENSION . . . . . . . . . . . . RUNNING-IN . . . . . . . . . . . . . . SPARKING PLUG . . . . . . . . . . . . STEERING HEAD . . . . . . . . . . . . TECHNICAL DATA . . . . . . . . . . . . TRANSMISSION . . . . . . . . . . . . . . WHEEL REMOVAL (FRONT) . . . . . . . . WHEEL REMOVAL (REAR) . . . . . . . . . . WIRING DIAGRAM . . . . . . . . . . . . 19 25 17 22 22 11 23 7 14 8 14 27 26 24 24 13 20, 21 12 11 27 10 16 27 5, 6 22 24 24 31 4 pages

TECHNICAL DATA Engine Number—on top of crankcase below cylinder. Frame Number—at top of steering head tube. Engine: Capacity . . . . . . . . . . . . . . . . . . Cylinder bore . . . . . . . . . . . . . . . . Stroke . . . . . . . . . . . . . . . . . . Compression ratio . . . . . . . . . . . . . . . . Piston ring gap . . . . . . . . . . minimum maximum Sparking plug . . . . . . . . . . . . . . . . Plug points gap . . . . . . . . . . minimum maximum Contact breaker points gap . . . . . . . . . . . . 174 c.c. 61·5 mm. 58 mm. 7·4—1 ·009 in. ·013 in. L7 ·020 in. ·025 in. ·015 in. Transmission: Gear ratios . . . . . . . . . . . . . . top second first 6·58 9·26 17·4 Clutch—friction plates . . . . . . . . . . . . . . 3 Chain size and pitch front ⅜ × ·250 in. . . . . . . . . . . . . . . rear ½ × ·335 in. roller . . . . . . . . . . . . 50 pitches 120 pitches Teeth on: engine sprocket . . . . . . . . . . . . 17 gearbox sprocket . . . . . . . . . . . . clutch sprocket . . . . . . . . . . . . . . rear chainwheel . . . . . . . . . . . . 16 38 47 Capacities: Fuel tank . . . . . . . . . . . . . . . . . . Petroil mixture . . . . . . . . . . . . . . . . Gearbox . . . . . . . . . . . . . . . . . . Front forks . . . . . . . . . . . . . . . . . . 2 gallons See pages 12 and 20 ¾ pint ⅛ pint each leg Wheels: Tyre size . . . . . . . . . . . . . . Tyre pressure . . . . . . . . . . . . Brake size . . . . . . . . . . . . . . front rear front rear dia. wide 3·00—18 3·00—18 17 p.s.i. 22 p.s.i. 5½ in. 1 in. 5

TECHNICAL DATA Carburation: Amal Bore . . . . . . . . . . . . . . . . Main jet . . . . . . . . . . . . . . Pilot jet . . . . . . . . . . . . . . Throttle valve . . . . . . . . . . . . Needle position . . . . . . . . . . . . Needle jet . . . . . . . . . . . . . . ⅞ in. 140 25 375/3½ 2 ·1055 General Details: Overall length . . . . . . . . . . . . Wheelbase . . . . . . . . . . . . . . Ground clearance . . . . . . . . . . . . Seat height . . . . . . . . . . . . . . Overall height . . . . . . . . . . . . Handlebar width . . . . . . . . . . . . 79⅜ in. 51⅛ in. 5½ in. 31 in. 36 in. 27¾ in. The recommended tyre pressures are based on a rider’s weight of 140 lbs. If the rider is heavier, increase the pressures as follows: — Front tyre: Add one lb. Per sq. in. for every 28 lb. Increase above 140 lb. Rear tyre: Add one lb. Per sq. in. for every 14 lb. Increase above 140 lb. If additional load is carried in the form of a pillion passenger or luggage, the actual load bearing upon each tyre should be determined and the pressures increased in accordance with the Dunlop Load and Pressure Schedule. 6

TAKING OVER THE MACHINE Before running the machine make sure that the fuel tank contains the correct mixture of oil and petrol, that the gearbox is properly topped up with oil and that the battery is filled and charged. (See appropriate chapters for filling instructions). Normally these preparations will be carried out by the dealer who is selling the machine and the new owner has only to arrange the controls to his liking and the machine is ready for the road. The Controls The new rider should make sure that he is quite familiar with all the controls before attempting to ride the machine. Most of the controls are adjustable and should be positioned so that they can be reached without moving the hands from the grips or the feet from the footrests. Handlebars should be adjusted so that a comfortable and natural riding position is achieved. Make sure that the bolts retaining the handlebar clamps are tight after completing any adjustment. Badly positioned controls cause poor control of the machine and will bring discomfort on long journeys. Handlebar Controls Twist Grip.—Mounted on the right handlebar it controls the throttle opening and consequently the engine speed. To open the throttle (i.e. to increase the engine speed) turn the grip so that the top moves towards the rider. Excess slackness in the cable can be removed by means of an adjuster incorporated in the cable at the carburetter end. The rotary stiffness of the twist grip can be varied by means of the adjuster screw and locknut. It is set for average requirements when leaving the factory, but can be readjusted to suit individual preference. Front Brake.—Lever mounted on the right handlebar in front of the throttle control. Grip the lever gently to operate the brake. Clutch.—The lever is mounted on the left handlebar. Grip the lever to free the clutch, i.e. to disengage the drive between the engine and the rear wheel. Horn.—The horn button is mounted on the left handlebar and is incorporated in the headlight dipper switch. Headlight Dipper Switch.—Controls the switching from main to dipped headlight beams and is mounted on the left handlebar. Other Hand Controls Air Control (Carburetter).—This is operated by the spring loaded plunger above the carburetter. Depress to give a rich mixture for starting purposes, raising immediately afterwards.—(Important see carburetter air control, page 19). Petrol Taps.—Under the rear end of the tank. To turn on the petrol, pull out the serrated button and lock in position by turning anti-clockwise. To turn off the petrol, reverse this procedure. Both taps communicate with the main supply in the tank but if one tap is used, a reserve supply is left which can be fed to the carburetter only when the second tap is turned on. One tap only is fitted to the Silver Bantam. Headlight Switch.—This is operated by a switch on the headlamp, and has three positions—OFF, LOW (L), and HEAD (H) respectively. The low position is for use when the machine is stationary. 7

Ignition Switch.—This is mounted on the top of the headlamp and has three positions. With the pointer straight ahead, the ignition is switched off, and the switch should always be retained in this position when the engine is stationary, otherwise after several hours (say, over-night) the battery may become discharged. For normal starting, rotate the switch until the position marked “I” is straight ahead. For emergency starting with a discharged battery, rotate the switch until position “E” is straight ahead. (Important—See Electrical Equipment). Carburetter Tickler.—This is a small plunger in the top of the carburetter float chamber on the left hand side. Pressing it down pushes down the float and frees the needle valve thus permitting the carburetter to receive excess petrol. Steering Lock.—Provision is made for locking the steering. Turn the forks to the left, when the hole in a special frame lug will coincide with the corresponding hole in the bottom yoke lug. Locking the two lugs together by means of a padlock, prevents the machine from being driven or wheeled away. Foot Controls Rear Brake.—On the left-hand side of the machine controls the rear brake only. Gear-change Pedal.—On the right-hand side of the engine there are two pedals one of which projects forward, this being the gearchange pedal. It affects the change from one gear to another. The lever is of the positive stop type and returns to the central position after each change. Upward movement of the lever selects the next higher gear, downward a lower gear. Neutral is between first and second gear. Starter Pedal.—This is the other pedal on the right-hand side of the engine. Depression of the pedal rotates the engine. Instruments Speedometer.—This is mounted centrally in the headlight body and records speed and total mileage. DRIVING To Start the Engine Turn the ignition switch to the position marked “I” (see “Controls”). It will be impossible to start the engine until this has been done. Stand astride the machine and make sure that the gears are in the neutral position, which lies between the first and second gears. If there is any doubt about this, depress the gearchange pedal fully two or three times to engage successively lower gears, at the same time easing the machine backwards and forwards to allow the gears to rotate a little, and so facilitate gear engagement. When it is certain that first gear is obtained, raise the pedal by half its normal stroke, so selecting the neutral position. Should the machine be in gear it will move forward as the starter pedal is depressed. If the engine is quite cold, depress the carburetter tickler momentarily. Note that it is neither necessary nor desirable to oscillate the tickler rapidly, as this may damage the float. Close the carburetter air control, thus giving a rich mixture for starting (see page 19). 8

Open the twist grip a small amount only, as excessive opening may prevent easy starting, and push the starter pedal down slowly until resistant is felt; then, without releasing the pressure on the pedal, give a firm downward swing which should set the engine in motion. If the engine fails to start at the first attempt, repeat this procedure, being careful to avoid rapid kicking at the pedal which will serve no purpose and may damage the operating mechanism. Note that while it is necessary to use the carburetter air control when starting from cold, this may not be necessary when the engine is warm, and should certainly not be so if a re-start is made after a short wait only. During normal running the air control must always be kept fully open and it should be opened immediately the engine fires, or should the weather be cold, at the earliest possible moment. Engaging First Gear With the engine running slowly, disengage the clutch by gripping the left handlebar lever and after a brief interval press down the gearchange pedal as far as it will go, so selecting first gear. If the pedal will not move through its full travel, so that the gear does not engage, ease the machine backwards or forwards slightly, maintaining a light pressure on the pedal, until the gear is felt to engage. Moving Off Open the throttle slightly and gently release the clutch lever part way, until the clutch can be felt to take up the drive, and the machine tends to move forward. Open the throttle a little more to prevent the possibility of stalling the engine, and slowly release the clutch lever as the machine moves away. Until the lever is completely released the clutch is not fully engaged, so that the engine should not be speeded up excessively or the clutch remain partly engaged, for longer than is necessary to get the machine away in first gear. Changing Gear (Up) When the machine is moving steadily with the clutch fully engaged, the next operation is to engage second gear. Close the throttle, disengage the clutch, and raise the gearchange pedal as far as it will go, the three movements being performed simultaneously. Immediately the gear is felt to engage, re-open the throttle and re- engage the clutch. A similar procedure is necessary for each upward gearchange. Changing Gear (Down) Open the throttle slightly, disengage the clutch, and press the gear change pedal down as far as it will go. Re-engage the clutch as soon as the gear is felt to engage. Violent pressure on the gear lever is unnecessary, a steady movement of the pedal being most effective. All downward gearchanges should be made in a similar manner. To Select Neutral Neutral is situated between first and second gears. To select neutral from first gear, withdraw the clutch and lift the gearchange pedal gently until it is felt to click into the neutral position. If the lever is lifted up too far it will travel through to second gear. 9

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BSA D7 175CC BANTAM Workshop Repair Manual

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