BSA 1971 B25SS Gold Star Workshop Manual Download Page 1

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Summary of Contents for 1971 B25SS Gold Star

Page 1: ...www bsaunitsingles com...

Page 2: ...gA Worl shop B25SS B25T B50SS B5OT BSOMX Gold Star Victor Gold Sta r Printed in EnSland at B S A Press May 19t 1 www bsaunitsingles com...

Page 3: ...e Replacement pants or accessories must be of B S A origin or as approved by B S A Motor Cycles Ltd In this respect your attention is drawn to the Tcrrms and Conditions of B S A Guarantee www bsaunits...

Page 4: ...t t tj a l d F o J o a Iri N lt Page 3 www bsaunitsingles com...

Page 5: ...2 f lt7 v c d F u1 o J o tt G N lr www bsaunitsingles com...

Page 6: ...4 1 d o F U q Ui ffi l1 www bsaunitsingles com...

Page 7: ...a a o d F o J F A q tr www bsaunitsingles com...

Page 8: ...a O d o F U ct ui A p a 7 ti ta C ta Page 7 www bsaunitsingles com...

Page 9: ...o o X d o F l F www bsaunitsingles com...

Page 10: ...ork of relerence even to the skilled mechanic All information and data given in this nlanual is correct at the time of publication but because of our policy of constant development changes in specific...

Page 11: ...all repair arrangements through their choseu dealer ln the great nrajority of cases local repail will be possible and this will avoid the expense inconvenience and possibility of the machine being da...

Page 12: ...RETTERS Anal Lirnited Holdford Road Witto r BIRMINGHAM 6 Renolds Chains Limited Renold House Wythenshawe M ANCHESTE R Joseph Lucas Limited Gt Hampton Street BIRMINGHAM I8 Girling Limited Birmingham Ro...

Page 13: ...glass foirings ore remotetl beJ tre handing the nqchine ot er for repair Accessorie t su h as nirrors or batlges shotid eltto t s be rcntoled beJbre entrLtstittg a tl1a hine Io ttt indepentlent torrie...

Page 14: ...CE DEPARTI 4ENT BEFORE DELIVERY II SIGN AND RETURN PRE DELIVERY CHECK CARD Fajlure to carry out these checks or to sign and retLlrn tl re pre delirerl check card rvill nullily arrange ments for the pa...

Page 15: ...nalily belorv 90 F 32 C shade tenlperatule TROPICA L Climates frequentl above 90 F 32 C shade tell1perature Specific grar ity fbr filling new cells r 260 at 60 F 15 5 C I 210 at 60 F 1i 5 C Specific g...

Page 16: ...E WRENCH SERVICE TOOLS USEFUL TABLES FRAME AND FITTINGS FRONT FORKS WHEELS BRAKES AND TYRES ELECTRICAL EQUIPMENT SETTINGS Se tiot1 GD A B c D E F c H J K L Page Ito13 l to 11 lto4l lto 8 Ito12 Ito 8 l...

Page 17: ...linder balrel Pi ton Pist on lirrgs Oil pun rp Connectirrg rod and crankshaft assembly Clutch Cearbox Ceal latios Sorocket ize tLeerhl t hlirrs FRAME AND FITTINGS Front olk Swinging arm Rear srr pensi...

Page 18: ...length inner Free length outer Fitted length inner Fitted length outer 3130 5010 0025 326 t 12 deep 64cm 135 5 nlm 44 5 mm 32 0 mm 34 8 mm 45 I 450 1 455 312 1 317 3095 3100 3090 3095 Hidurel 5 3120 5...

Page 19: ...Oversizes M aterial PISTON Compression ralio Clearance top oi skirt Clearance bol1 m of skirt Gudgeon pin hole diameler Material PISTON RINGS Width top and centre Width scrapers Depth top and centre...

Page 20: ...and right Big end journal lunning clearance Crankcase main bearing roller Ieft Crankcase main bearing ball right 6890 6894 1 5630 1 5635 5 312 437 5 t 4380 010 020 0 10 25 50 76 mn 9841 9844 0005 0015...

Page 21: ...load Type Rear chain Pitch Roller dianreter Distance between plates Length Breaking load Type CARBURETTER EXCEPT Type Main jet Needle iet Needle position Throttle valve Choke dianeter Throttle slide...

Page 22: ...SPRINCS Free iength inner Free length outer Fitted length inner Fitted length outer Phosphor bronze 3120 30 5005 50 t0 r 859 0015 0025 323 326 12 deep VALVE TIMTNG Tappets set to 015 38 Inn1 fnr chec...

Page 23: ...sion atio Clearance 1op ol skirt Clearance bottom of skirt Gudgeon pin hole diameter Material l0 l 005 007 0035 0045 7499 7 501 Aluminium alloy H G 4l 1 127 134 138 145 061s 0625 1550 1560 00r 003 0 t...

Page 24: ...n plates Or erall thickrter of fiictiun Free length of springs Clutch pushrod length Clutch pushrod diameter Clutch rollers GEARBOX Type Multiplale rvith integral cush drive 5 5 167 1 66 9 0 1875 1875...

Page 25: ...meter Distance between plates Length Breaking load Type 37 5 250 225 72 links 1 900 lbs ol 400 255 106 inks B50MX 5 000 lbs Renolds 110 054 FRAME AND FITTINGS FRONT FORKS Type Steering head bearings S...

Page 26: ...ront Rear Spoke sizes l0 10 WHEtrLS BRAKES AND TYRES 825T B5OT B5OMX WMl 20 wM3 x lE B25SS U S A only wM2 18 WM2 i l8 l0swG 6 42 loswc 6 3l l0swc 7 73 825 B5OSS 825 Fleetstar WM2 r I8 wM2 r 18 The len...

Page 27: ...ear road 825 B50SS K70 3 25 I8 3 50 i 18 B25T B5OT Trials Unirelsal 3 00 20 4 00 l8 22 24 l0 t4 B50MX Sports 3 00r20 4 00 x 18 8 l2 22 24 EI ECTRICAL EQUIPMENT Batte4 Capacitor Coil lgnition capacitor...

Page 28: ...ns Litres OIL RESERVOIR British pints Litres GEARBOX British pints cml 4 2 25 825 B50 T 85 216 s4 t37 7i 0e 29 73 7 32 81 43 s 110 5 I ll 4 B5O MX 82t 2o9 54 137 7 te 33 85 32 81 43 s r10 5 3 3j 13 5...

Page 29: ...y the number of teeth on the rear wheel sprocket B divided by the number of teeth oll the gearbox sprocket C lor example GEAR RATIO CALCULATION clutclt sprocket 52 reor vheel sprocket 52 e gifie sprcc...

Page 30: ...L PRESSURE AND NON RETURN VALVES Plessure releuse rlLre Non r et u rn valre Lou orl pressure Clankcase oil pipes Crankcese breaiher INDEX Page A2 A4 A4 A7 A7 A8 A8 A8 A8 A9 A6 46 CONTACT BREAKER GEARB...

Page 31: ...rease clutch cable Grease swinging arm bearings Grease speedometer drive 3 l5 4 5 5 16 6 7 l8 8 3 2 9 I 10 n 12 11 Page A9 Page A9 Page Al I Page A8 Page A8 Page Al0 Page Al0 Page Al0 Page A9 Page A9...

Page 32: ...50 LUBR ICATION A3 Ftc Al Generql lubricttlion liagrotn br all nodels The nurrbers in circles ret er to the right side of the ttlachine and numbers in squares refer to the Ieft side www bsaunitsingles...

Page 33: ...90 for ks Q Matic chaincase 250 c nr onlv e55C0 grease LBl0 Filtrate nrotor and chaincase oil Super 20W 50 rrausmission gear box Ep90t lcrks AT Fluid F chaincasc 250 crr3 only Supel l0W 30 grease Sup...

Page 34: ...4 il i I I t I h A _ z o 1 Ftc A2 Gererql engine lubrit tttion eliagrun A Non return valve feed side D Pressure release valve B Sump plale and lilter F Crankshaft sludge trap C Non returr valve return...

Page 35: ...enge side ol the pump being greater than that ol the feed gears a mixture of oil and air will be seen to enter the reservoir from the re turn pipe If oil pressure exceeds the intended maximum a releas...

Page 36: ...opens and leleases excess oil direct to the crankcase fronr where it is returned to the reservoir The valve is pre set at the Works to opert at a pressure of 80 100 lbs p s i B25 or 45 50 lbs p s i 8...

Page 37: ...gine causing lr rbricatiotr problens and oil leaks Therefote it is nost ii nportant that a regular examination of the breather pipe be made to ensure that it is clear and lurrctioning correctly CONTAC...

Page 38: ...drained and refilled erer 1 4 000 rrile b 500 k 1 Draining procc dulc is the same as for 850 models described below PRIMARY DRIVE 850 models On 850 models the primary chaincasc oil level is rnaintain...

Page 39: ...ase is packed around the bearings on assembly to last a very considerable mileage at least until a conlplele overhaul is required Machines litted witl r g ease nipples should have the bearings grcased...

Page 40: ...ting the rear chain is to rcnrove the chain every 2 000 niles 3 000 km wash it thoroughly in parallin and allow to clrain Immerse it in a bath containing one of the nllny special preparations availabl...

Page 41: ...ng the cylinder Jread Cylinder brllcl Removing the cylinder barreJ Removing the piston Piiton rings Small errd bttsh Reassembly altel dec rt bnrri irtg CHECKING VALVE CLEARANCES B50 rrrodel 825 nrodel...

Page 42: ...lnp Rehu iid irre tlte ort pun p Refittirrg tlre oil prrnrp Tintirrg gelr Trrppet Bl9 820 820 820 820 821 822 823 o 823 824 824 825 B25 F 26 TACHOMETER DRIVE Disrrantling and r cassembly CEARBO DISMAN...

Page 43: ...ENGINE 825 engi ne e xplotletl www bsaunitsingles com...

Page 44: ...B4 ENGINE 825 850 di FIG BiB 850 en qine expktrlal www bsaunitsingles com...

Page 45: ...om the engine is transnitted through the engine sprocket and duplex prinrary chain to tl Le clutch assembly which has a built in cush drive Here the drive is taken up by the bonded friction plates and...

Page 46: ...and 65 249s inner B50 Nos 71 2223 outer and 40 1007 inner B25 A supply of pataflin and clean rag The fuel tank must be removed in order to gain access to the cylinder head see page D 10 Release the en...

Page 47: ...ciue to r enew iluy dilnraged washers B50 r ocker spindles are fitted with lLrbber sealing rings rvhich ntrLsl bc in good conditiorr The rings rnrLst be renewcd if danta eed Refer to Figs 8 1 whcn le...

Page 48: ...rrrrrle r 45 Sonrctinrcs rvhcn an cngine lus been declr bonised 11r i11y tinres lalves becone pocketed Whcn 1he virlve head and seat are belorv the u r l rcc f ltc co rr rbuslio n c hu rr ber so inr...

Page 49: ...and valve seats Smeal each valve stem with clctn cnginc oil lrrtd re1 lace tlte rrrlre trt llte lterrrl Fit the spling cup virlr e sprin rs rvith close coils at the bottorr and loll collar over each...

Page 50: ...lnust be warmed in order to expand the material FtG 88 Checking piston ring groore ol which it is nadc In this way the gudgeon pin may be renroved without risk of damaging the piston or connecting rod...

Page 51: ...d The ll25 does not hale a replaceable bush the coDll lete connecting real lnust be replaccd FICi B 9 Using Seti e tool No 61 3653 to rentove snull end hush 850 only Bil Using service tool No 6l 365 j...

Page 52: ...heck that the push rods are correctly Iocated place a new cylinder head gasket in position and re6t the head complete with rocker box Now using a torque wrench tighten the six cylindel head tixing nut...

Page 53: ...turning lrom valre spling pressure Frc Bl3 Valve rocker q liustnent 825 Before adjustnert thc flals milled on lhe right end of the rocker spindles E Fig 813 n rust face each other as illuslrated This...

Page 54: ...e exhaust ralve lifter cable ifiittcd Remo e the ch in uiirej front extension see page D 6 and tincouple the rear chaitr Detach the c l r in frort tlre nrachine Dis connect 1he clutch cable r rsing a...

Page 55: ...NGINE Br5 So lhat the clutch cel ttre nut nray bc un screrved the clLrtch centre and chairtrvhecl nrust be iocked togcther n ith scrvice tool No 6l 377 1 atld a bar inserted th ough lhe colnecting r o...

Page 56: ...is buckled and must be replaced Clutch centre and cush drive To inspect the cush drive rubbers which are contained in the clutch centre take out the four countersunk head screws adjacent to the clulch...

Page 57: ...st onto the rear of the plate on reassembly this boss rnust be at the four o clock position as it will otherwise foul the rear chain Look for signs of oil leakage down the back of the cover lf leakage...

Page 58: ...re sefvice tool No 6l 3583 into position in order to plovide rreans of holdirrg the assembly Pick up the assembly irr both hands and locate the sprockets over their respective shafts Fig Bl9 Ensure th...

Page 59: ...ral screw and locknut on the plessure plate The pushrod must also be adjusted in this way so that the clutch operating lever on the tinling cover lies at an angle of approxinately 30 to the cover join...

Page 60: ...oints gap advances the timing closing the gap retards the timing Although this variation is very slight it must be remenbered that accurate timing is essential if optimum performance is to be achieved...

Page 61: ...f the left crankcase and insert the tool body Gently push the tool plunger into engage rnent with the hole that is drilled in the flvwheel FtG 822 Ignition pointet positiot tj At this slage the auto a...

Page 62: ...linc adjLrstment nray be nade by mcans of the eccentric F Tighlen the screws C The engine nlav now be sta tecl and the tir ning clrccked by stroboscope TIte intnot tatree f racrrr rlc t ttittotr titt...

Page 63: ...kickstarl quaclrant in place Renrovc the contircl bleirker aLLlo advanca unit Take out the renaining lixing scrcws noting their Iocalions and break the crank case to cover joint by lapping the cover g...

Page 64: ...thoroughly irr pelrol arrd allow to dry before exanrining Look for foreign rlatter janrrned in the gear teeth and deep score narks in the pump body These wiilbeevident if regular oil changes have bee...

Page 65: ...ylon inserts and it is most important that any replacements are of this type Any alternative nut must be sealed with a drop ol Loctite to prevent it comirrg loose in service Timing gears Careful exani...

Page 66: ...e crankcase aperture of standard engines is covered by a srnall plate llxed with two screws Ftc 830 Tacltonter drite e rplolerl Dismantling and reassembly Due to the position ofthc tachoneter drive Jp...

Page 67: ...ctor pull out the piYot with a pair of pliels The canplate may now be taken out together witb the selector forks arrd their spirrd le perrrit ting removal ol the layshaft complete with geals and the m...

Page 68: ...d fit the main gearbox bearing Refit the oil seal and gearbox sprocket remembering to berrd up the lock washer The correct torque for the nut is I00 lbs ft If necessary llt a nerv inner cover bearing...

Page 69: ...and retain it with a dab of grease Fit the layshalt thrust washer ensuring that the side having a chamfered internal bore faces the gear lf the washer is reversed the H Luyshtr i botton geur shint J L...

Page 70: ...into position as illustrated in Fig 836 Hold the quadrant in the left hand and the coil of the spring marked side upper lnost between the thumb and forefinger of the right hand Turn the coil over at...

Page 71: ...after lemoral of the kickstart quadrant WJren doing this be very careful not to damage the bearillg surlace ol the shaft See Fig B35 for the position of each washer the lhicknesses and part nunrbers...

Page 72: ...n lbr kickstarting the engine This is the position shown in Fig B39 Neutral geT pasitian Thc spring plate is holding the cant plate b the secol d notch At the other cnd olthe clnt plate 1he seiector q...

Page 73: ...s to move the camplate to the first gear position The layshalt sliding gear is engaged wilh the layshaft first gear by movement of the Iayslraft seleclor lork The plungers are poised to nlove the clrr...

Page 74: ...ows to nlove the camplate to the first Sear position The layshalt sliding geal is engaged with the layshaft first gear by movement of the layshaft selector lolk The plungers are poised to move the can...

Page 75: ...gear is engaged with the layshaft second gear having been moved by tjre layshaft selector fork Fig 841 shows the quadrant plungers in the canplate windows ready to n1ove the gears from second to eith...

Page 76: ...es both selector forks The lay shaft sliding gear moves to a neutral position and the mainshaft fork engages the mainshaft sliding gear with the mainshaft third gear n the camp ate windows the quadran...

Page 77: ...the trrainshall sliding gear into engagement with the mainshalt sleeve pinion The top quadrant plunger is now conccaled behirrd the camplate and only t Jre Iower plun ser is able to engage in a wirrd...

Page 78: ...ejoint Thiswill only damage the joint laces resulting in oil leak FrG 845 Using tool No 61 3778 to rcnotre the rollet heqring inner rute Suppoft the craflkciise asscmbly timing side uppermost see Fig...

Page 79: ...f a small tag To assist in correct reassembly the rod and its cap are marked at the front or rear face with a centre punch These n arks must be adjscent on reassembly Examine all parts carefully If th...

Page 80: ...iotl without lilrther rovelnent Drillirrg must bc corrfined 1o the thicker por tion ofeach flyrvheel opposite thc balance weight and rrust be carlied ou1 equally on the periphely of both wheels fhe lr...

Page 81: ...uc1ed ress the crirnk rin litnriv in position lhen fil thc drivc sidc 11rrvhee1 Replacc Lhc clitnkpin nuls ancl Iightcn lo 200 lbs 11 fhc llyu hcel assenrbir rrjll nou hatc lo bc I I LI CCI Fll rvhec...

Page 82: ...kcase This operation wili be simplified if the case is snpported on a wooden box of the dimensions shown in Fig 850 Apply a thin coating of Loctite Plastic Casket 10 one joint face of the crankcase ha...

Page 83: ...ir cleauer Effect of altitude on carburation Page C3 c3 C4 C4 C4 C4 c4 C5 C5 C5 c5 C5 c5 C6 C6 TRACINC FAULTS lndications of richness lndications of weakness To cure richness To cure weakness VARIABLE...

Page 84: ...THROTTLE NEEDLE o RINC TICKLER MIXING CHAMBER NEEDLE JET JET HOLDER FLOAT SPINDLE FLOAT NEEDLE FILTER BANJO BOLT 9re Prlor ArR scREw THROTTLE VALVE ADJUSTING SCRFW MAIN JET FLOAT FLOAT CHAMBER BODY W...

Page 85: ...e neeclle jct available for snap acceleration DTSMANTLTNG AND REBL ILDINC THE CARBURE TER Unscrew thc clip sccLrling lire air flltcr hose 1 tllc ctttrrlrettcr rcleasc ihe tqo fixill g nuts rrtrrl rrit...

Page 86: ...el gaskel Replace anv othel larts that ira e oll r HINTS AND TIPS throttle cable There should be a nininrun of backlash rvhen the twist grip is tulned back and the tltrottle cable mlrst be routed so t...

Page 87: ...size rviil ccrreci this vcirkncss thoLrgh thc linal setiing nrrrsl be delclmiDccl by lrial arcl erlor lt ma1 be ncccssni y to flrise the ncecll j fll cct of altitudc on carburalion Increasecl altituc...

Page 88: ...valve with a lar ger cut away see paragraph 3 page C8 Position D Lower needle one or two grooves see paragraph 4 page C8 Sequence o f tunittg C Third Srage open D Fourth Stage to open Throttle cut ara...

Page 89: ...cirl il ir I riclter rrrirtrrr Tickler or primer This is a sn rall sprir rg loaded plLrnger in the carburetter body When pressed dorvn on the floal the needle valve is opened and so llood ing is achi...

Page 90: ...on is poor laise the necdle a groovc lr1 n linre until thc best rc sults irle obtaincd Il the nixlure is too rich e ven uith thc clip il r thc tol groo c the neeclle iLncl nccdle ict probabl need rcpl...

Page 91: ...models Trail and MX Models Street Sclambler Models SEAT BATTERY CARRIER AND TOOL TRAY D6 D7 D1 D8 D8 D8 D9 D9 DIO Dl0 Dl0 Di0 Dl0 Dll D1l D11 Dt2 D1Z CH INC L ARD REA R SHOCK ABSORBERS PROP STAND CENT...

Page 92: ...D2 FRAME AND FITTINGS 825 850 93 y t t g6s t a l l o l j r _ O _ l r tt ll t t lt lo ro o l 1t o Ftc Dl Frone dinrensions www bsaunitsingles com...

Page 93: ...to set points 4 palallel in which case points B carl be used If the machine has been subjected to froltal irrpact the nrain tube may remain parallel at points l bLrt will be bent behind the steerir r...

Page 94: ...s will be apparent Mark all soulces of leakagc and le rveld The aillirre from a tyre sellice punrp lili be suitable if the gauge is firs1 set to the abo c ligure As iln alternatile a foot pr rnrp rray...

Page 95: ...removed with the fingers and the bushes rvithdrawn using a pair of pliers Take care tlot to danage the bearing surlace of the bushes if they are to be refitted The bearings thens lves n tav llo r be d...

Page 96: ...ustrated so that the pivot is vertical Next find the centre of the pirot and check tlrat all dinrersions are in accordance with those given in Fig D6 Note There nay also be a variatio r in the rear da...

Page 97: ...olts are removed On re assembly new mounting grommets should be litted if the old parts show signs of chafing REAR MUDGUARD Alt models Before removing the rear mudguard the seat battery and batterycar...

Page 98: ...d is rubber mounted to the frame at three poil rts Disconnect the battery terminals unclip the fixing strap and lift the battery out of the carlier Note that a vent pipe is fitted to cally corrosive f...

Page 99: ...ch FtG D8 Cqm ing positions A Light settiilg B Mediw1l seltii g C Heaw setting easier if a little soapy watel is applied as a lubricant The danpers have three load positions as illustrated below arrd...

Page 100: ...fuel tank and the tank is mounted on two rubber pads over the frame tube Two rubber plugs steady the tank at the front It is not necessary to remove the centre bolt nut entirely in older to take off t...

Page 101: ...pring iusert the nipple of the replacemeDt cable through the valve needle hole and locate it in its housing Fit the throttle needle assernble the throttle valve to the carburetter body naking sure tha...

Page 102: ...ion This is done by nreans of the adjuster in the clutclL pressLrre plate see pa ee B 19 Exhaust valve lifter cable B50 onllJ Undo the handlebar control lever pivot bolt and nut Pull the lever away fr...

Page 103: ...G HEAD BEARINGS Dismantling the steerin s head REASSEMBLING THE STEERING HEAD DISMANTLING THE FORK LEGS Changing the fork springs Dismantlir r s the damping assembly Tlre oil sea ls REBUILDING THE FOR...

Page 104: ...engine so that the lront wheel is lifted cleal of the ground Ftc E2 Steerirtg heocl uijustnrent Then standing in frout of the machine leel for play on the head bearings by alternarely pusJ ring and p...

Page 105: ...ing a hide nrallet strike the sides of the top yoke alternately fronr belorv to release it l rom the tapered stanchions Draw the steering column Iower yoke and fork legs downwalds and out of the frame...

Page 106: ...ay them on the petrol tank which should be protected by a piece of cloth Unscrew the top nuts using spanner No 60 0779 and take out the main springs It is llot necessary to ren love the fork stan chio...

Page 107: ...ks and steering head may be con pletely dismantled The oil seals Two oil seals are used in each leg One takes the form ol an O rilg around the darnper valve and the other ofthe garter type is pressed...

Page 108: ...e steering head page E2 at this stage Having fully tightened the top nuts to 50 55 lbs lt lo dlaw the nratirrg tapers of the top yoke and stanchions together renove the nuts until a later stage New oi...

Page 109: ...cllions into the botton r yoke and tighten the pinch bolts When in spected fron the side the stanchions should be palallel and this conditiorr nray be checked on a surface table If the tubes are not p...

Page 110: ...harp blorv using a lead lrarnrrrel ol a hanrnrel ured ir c njunctiorr Yith a soft metal drifi Check the alignment again uith the gauge ard if necessary give correctiou blows in the above nanner until...

Page 111: ...bearings RefiLtirrg the bearine REAR WHEEL All models Wireel removal Brake shoes Removing the bearings Refitting the bearings Rear wheel sprocket Wheel replacement REAR CHAIN ADJL STMENT RENEWING BRAK...

Page 112: ...renewed On re assembly grease the cam spindle and shoe pads lightly bLrt be careful not to over lubricate as grease lnay contact the linings and impair braking efliciency Adjustnent is by means of the...

Page 113: ...k Iegs locating the brake anchor plate stud in the slotted ear on the lork outer nember Fit the wheel spindle ends on the upper hall of their mountings and pr rll the lbrks downrvards to re tain the w...

Page 114: ...rom the inside using a suitable drift The wheel spindle may be used for this purpose but ensure that the shoulder at the right end contacts the bearing and that the spindle end is protected frorn dlrt...

Page 115: ...it is preferable to replace then in their original positions if they are not rerlewed Ftc F5 Rear lub On reassenbly glease the ca r spildle and shoe pads lightl but be careful not to over lubricate as...

Page 116: ...t of the biake drunr llange A socket or tubrLlar spanner is needed to reach lhe nuts from the risht side beflr een the spokes 4 heel replacement Fjt the assenrbled brake anchol plate into posi tior r...

Page 117: ...the followirrg procedure Holil the shoe firn rly in a vice and using a good sharp chisel cllt off the head of the li et Ftc F8 Peeninq oter riyet s Drive ou1 the old rivets rvith a suitable puuch Rere...

Page 118: ...ke replace ment spoke tensioning and wheel truing are operations which should not be treated lightly Careful examination of the wheel will show that every spoke is opposed by anotl ler on the opposite...

Page 119: ...nally marked lf security bolts are to be used tl le nLrst be litted before balancins SECURITY BOLTS If a tyre is used in an under inflated condition it will creep round the rinr taking the tube with i...

Page 120: ...the wheel as indicated by the arrows to correct alignment Assumirrg that chain ad llstment is correct movement of the rear wheel will be made olt the right side chain adjuster A machirre suflering ac...

Page 121: ...arld prise the bead over the flange holding the free part with the other lever Remove one lever and insert further alo g the bead continuing every two or thlee inches until the bead is completely rem...

Page 122: ...fitted midway between the bolts This will ensure a high degree of tyre balance lf the spokes have been tensioned or renewed they must not project through the llipples FiJe flush any that are showing...

Page 123: ...n pull the valve back firmly into posi tion Also erlsure thaLt the tube is restins ol the flap of the security boit and is overJapping the sides Check that the fitting line on the tyre rvall just abov...

Page 124: ...d high speeds rolmal pressLrres should be irrcreased by 5 lbs per square inch Il r pillion passenger or lu 9gage is calried the actual load on each tyre should be taken and the pressures increased in...

Page 125: ...identificltion Peliodic chec E fliciency check Ser ice notes THE SP RKINC PL UC THE CHARGING SYSTEM Part A Checking alternator output Part 8 Rectifier maintenance and testing Testing the rectifier on...

Page 126: ...ECTR ICAL SYSTEM 825 B5A g 11 lel Electritql box A Zener diode B Condenser C FIasher unit D Capacilot E Ignition n aster svit h F Rectif er G Headlantp harness socket H lgnition coil www bsaunitsingle...

Page 127: ...rated enc lpsLrlated stator with a rotor carried on and driven by an extension of the crankshaft The rotor has an hexagonal steel core each face of which carries a high energy permarent magnel keyed t...

Page 128: ...s not beirg used ir is inlportant to give it refreshing charges at the appropriate re charge rate These should be given fortnightly in temperate cljmates arld weekly in the tropics THE IGNITION SYSTEM...

Page 129: ...00 turns respec tively of shellac insu laled ire the secondary being much finer Each layel is paper irrsulaterl fron the next on both prinary and secondary windings To test the ignition coil on the rr...

Page 130: ...ofdirt ormetal dust with a clean petrol gasolene moistened cloth The contact faces should be slightly domed to ensure point contact There is no need to remove pitting from the fixed contact When refit...

Page 131: ...cii cuit conditions Also check the earth connec tions Do rot run the rrachine rvith the Zener diode disconnected as the capacitor will be darlaged due to excessive voltage lf difllculty is encountere...

Page 132: ...stration E is seen a plug which is conpletely worn out and in need of replacement To clean the 1 lug it is preferable to rnake use of a properly designed proprietarv plug cieaner When the plug has bee...

Page 133: ...0 volts minimum From the results obtairred thefollorvine deduc tions can be r nade l lfthe reading is equal toorhigherrhanthose quoted then the alternator is satisfactory 2 A lorv reading indicates e...

Page 134: ...are conducted A voltmeter in ltosition Vl rvill nteasure the volt drop across the rectifier plate In position V2 it will easure the supply voltase to check that it is the recom rended l2 volts on Ioa...

Page 135: ...olts minimum lf the readings obtained are not within the figures given thell the rectifier illtelnal connec tions are shorting and the rectifier should be renewed PART C Checking the chargir g circuit...

Page 136: ...he Zener diode output regulating systenr which uses the coils of the alternator connected perma nently across the rectifier provides automatic control of the charging current lt will onJy TERM INAIJ B...

Page 137: ...rt to read The next check occurs when the ammeter rises to 2 ampsr at this point the voltmeter should ead between 13 5 andl5 5 volts Conclusions The Zener Diode must be re placed if I Current flow col...

Page 138: ...ugh a small hole ir r the side of the switch body A and the lock assenbly withdrawn after the whole unit has been detached from the electric box HANDLEBAR SWTCH FUNCTIONS The left handlebar switch con...

Page 139: ...lamp unit until the beanr is correctly aligned Do not lorget that the headlamp must be on main beam during this operation Tighten the nuts fully after adjust ment TAIL AND STOP LAMP UNIT Access to the...

Page 140: ...ning lights and the parking light access being gairred to each of them b first temoving the rilr and light unit asserrbly The speedometer light is housed within the bnse ol the speedonleter head t rcl...

Page 141: ...ener diode Plug aDd socket 9 pin lgnilion capacitor Ignition coil CoDtact brcaker Left handlebar swirchcs Hom Right handlebar switches Cable color code Black Blue Brown Red Purple Creen Slatc Light Sn...

Page 142: ...NS HI INDN X PRIMARY CHAIN Lubrication Adjustment H2 H2 H2 H2 H2 H2 H2 H3 REAR CHAIN Lu brication Adj usl menl CHAIN MEASUREMENT CHAIN ALTERATIONS AND RENEWAL CHAIN AND SPROCKET INSPECTION www bsaunit...

Page 143: ...ess with out deterioration As there are a number ofspecial chain lubricat ing preparatiors on the market we lecontnend that one of these be used As an alternative a heavy oil of S A E 140 grade may be...

Page 144: ...rts shoLrld be replaced b1 l riveted outer link CHAIN AND SPROCKET I SPECTION Sprockets on a new rnachine rvill be correctly aligned but nralalignnent may arise in use Thi s rnay be due perhaps to sla...

Page 145: ...n the case of more powerlul nodels It may be advisable on such nachines to re place the spring link at say 5 000 mile intelvals the reason being that ofnecessity the detachable plate on this link has...

Page 146: ...on r od errd cap nuts 825 Clankcase slud nuts Crankpin nuts 850 Crankshaft piniorr rrut B25 Crankshaft pinion nut B50 Cylinder head nuts 825 Cylinder head nuts 825 Cylinder head nuts B50 Cylinder head...

Page 147: ...lt addirional levera se of say l 15 15 Consequenllv ltett usin s a 1 extensio r with a torque rench graduated in lbrlt it rvould be uecessllry to set the u rench to a readillg ol 2 l lb 1ft in order...

Page 148: ...N NUT SOCKET Page K2 K2 K2 K3 K3 K3 K4 K4 K5 K5 K5 K6 K l K7 K8 K8 K8 K9 K9 K9 K10 K10 Kl0 CRANKSHAFT BALANCE WEIGHT MAIN BEARINC INNER RACE EXTRACTOR STROBOSCOPE TIMING LIGHT KIT TGNITION TIMINC TOOL...

Page 149: ...r holder and pilot set 60 1832 Valve seat cutter small 60 1833 Yqlve seal caller medium Valve seqt cutter latge Valt e seat blender sma l Velre seat blender large Frc K1 60 3 769 60 183 5 60 1836 v z...

Page 150: ...825 850 SERVICE TOOLS K3 Frc K2 6t 5035 Volrc grinding tool Frc K3 6 t 334 t Vcth e s ptittg t ont pressor Frc K4 Piston ring slipper 825 6l 3682 65 70 mm B50 6l 61 12 80 85 mm www bsaunitsingles com...

Page 151: ...K4 SERVICE TOOLS 825 850 FrG K5 61 3382 Vnhe guicle f t ing und e t acling plnldt Flc K6 SnraIt end bush extactor B50 6l 36s3 www bsaunitsingles com...

Page 152: ...c K7 Pitliorl extroctor set 6l 3 773 f5 IJ fF NT FI Nrl l lt t L TY lll lli tit t l Itl s o o a g T fSt s il tf II t FIG K9 B2s 6r 6124 Crank shaft balance weight Frc K8 B50 6l 3770 Crqnkpin nut socke...

Page 153: ...K6 SERVICE TOOLS 825 850 Frc K 10 61 3778 Main hearing inner re e exlru tot www bsaunitsingles com...

Page 154: ...825 850 SERVICE TOOLS K7 Ftc Kl1 00 5177 Stroboscope timing light kit Flc Kl2 60 1859 Ignition tintitg tool R 4 m www bsaunitsingles com...

Page 155: ...KB SERVICE TOOLS 825 850 o Frc Kl3 6l 3583 C lutdl sleere e tt 0ttot Frc Kl4 61 3700 Clutch nut scrcrr th iret Frc Kl5 6t 3714 ClLttch Iocking tool www bsaunitsingles com...

Page 156: ...825 850 SERVICE TOOLS K9 Frc Kl6 6l 61l3 Fork damper wlve tool Frc Kl7 60 0779 Fotk Iop tlut sponner FIc Kl8 6l 6121 Steering head bearing drift www bsaunitsingles com...

Page 157: ...SERVICE TOOLS 825 850 Frc K 19 6l 6025 Fork aligrlnletlt geuge Frc K20 6 t 3503 Rear darnper tlisntanl I ing cutl qssembb tool Frc K2l 6 t 3694 Ilheel bearing rctainer peg spronet www bsaunitsingles...

Page 158: ...W THREADS B S C SCREW THREADS FORMERLY C F I UNIFIED SCRTW THREADS B A SCREW THRTA DS MILES PER GALLON TO LITRES PER 1OO KILOMETRES GALIONS TO LITRES PINTS TO LITRL S POUNDS PER SQUARE INCH TO KILOGRA...

Page 159: ...1 8 685 8 939 8 1193 8 8 203 2 457 2 7ll 2 965 2 1219 2 9 228 6 482 6 136 6 990 6 1744 6 o ONE INCH 25 399978 nrillimetres ONE MErRE 39 370113 incbes ONE MrLE 1 6093 kilos ONE KTLoNTETRE 62138 miles T...

Page 160: ...2094 21 6062 25 0031 i9i32 20 r125 328125 10625 3r l l li t5 5116 1 15 3750 16 27 t9 20 6315 21 034 21 1312 17 0656 17 4 15 45i 6 1 17 8594 13 2562 16 6687 18 6531 19 0500 765625 19 4469 19 8437 2 t3...

Page 161: ...0 06 00236 0 07 oo276 0 08 003t5 0 09 00354 MM i0 60 70 80 90 0 1 96851 2 36221 2 75591 3 14961 3 54331 2 00788 2 40158 2 19s28 3 r 8891 3 58258 2 2 O4725 2 4409s 2 83465 3 22835 3 62205 3 2 08662 2...

Page 162: ...0635 No oF GAUGE INIPERIAL STANDARD WIRE GAUGE BRowN Sr RPE s AMERICAN WIRE CAUGE INCHES MII I IMETRES INCHES MILLIMETRES 0000 000 00 0 1 2 3 1 5 6 7 8 9 10 11 l2 I3 t4 l5 l6 t7 18 19 20 2t 22 23 24...

Page 163: ...THD ROOT sQ rN 02 2 P NI ITCH D JT Nlt 2100 AMETEI trIA 2180 l___ I ztes l3nr 0 3918 LT IIIN 2135 2111 oo 3865 Itt MEAN 522 s9 107 81 X CORNERS 61 ut 8l NUT THTCK ESS 005 107 1i1 20 5i r6 IE 1i1 2412...

Page 164: ...2608 0 2401 s 16 26 0 03846 0 0205 0 3125 0 2920 0 2715 3 8 26 0 03846 0 020s 0 3750 0 3545 0 3340 7t6 t 26 0 03846 0 0205 0 437 5 0 4170 0 3965 20 0 0s000 0 0266 o 437 5 0 4 r 09 0 3843 I l t t 26 0...

Page 165: ...3194 i n 0 0305 0 4321 0 4016 0 3710 20 0 0305 o 4946 0 464r o 4334 L l8 0 0341 0 5568 0 5t27 0 4886 s l8 0 0341 0 6193 0 5852 0 5511 I 28 0 0219 0 9955 0 9736 0 9517 1 28 0 025 I I 250 2202 1 2144 o...

Page 166: ...r r s3 t5 r l0 I30 9 12 2s l r 08 I 30j 9 26 26 t0 87 31 9 tI 61 l0 06 3l 897 2 t to 46 32 8 8 l 27 10 27 32 8 69 28 10 09 33 8 56 18j 9 cr 3lj 8 41 29 9 74 1 34 8 31 291 9 s8 341 8 19 50 5 65 60 4 7...

Page 167: ...6 913 8 295 9 678 11 060 12 443 0 138 1 521 2 093 4 286 5 668 7 051 E 434 9 816 ll t99 I2 58r 0 211 r 659 3 0 12 5 807 7 189 8 572 9 954 11 337 12 119 0 415 L797 3 r80 4 562 5 9 15 7 328 8 7t0 10 093...

Page 168: ...ROAD IIIRMINOHAM II ENGLAND Copyrigit f PUBLISHED BY SERV CE DEPARTMENT B S A I IOTOR CYCLES LID ARMOURY Printed i Enelaod at rbe B S A Press J www bsaunitsingles com...

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Summary of Contents for 1971 B25SS Gold Star

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BSA 1971 B25SS Gold Star, Workshop Manual

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Summary of Contents for 1971 B25SS Gold Star

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