Hints and Tips

BMW Motorcycles are pretty reliable, but they do need maintenance - it's no good buying an old (or not so old!) BMW and expecting it to perform flawlessly, year in and year out, after receiving nothing more than the lowest level of maintenance. Many of the necessary tasks are not included in any manual, and some of the most annoying traits, such as dripping carburettors, seem to have been accepted as being all part of BMW folklore.

There is no good reason to accept these regular problems, as there are few tasks which require great skill, particular knowledge, or special tools, and what is necessary can often be improvised or hired from the BMW Owners Club.

SAFETY IS PARAMOUNT! Always remember that working on your motorcycle can be fraught with danger the risks range from having it fall over on top of you, to setting it and your house on fire, not to mention the possible consequences of poor work, which could result in an accident at speed! Decide what is involved, and obtain any necessary spares before you begin work. Always keep the machine well secured, use the correct tools, keep the workplace clean and tidy, keep children away, check your work carefully, and if you have any doubts, ask someone who knows your life, and those of others, could be at risk. If in doubt, don't do it!

Oil Filter Replacement can wreck your engine, if the steel shim and '0' ring of post-'76 models are not fitted correctly! Always fit the shim into the crankcase, then place a new paper gasket onto the cover, followed by a new '0' ring. Modern filters have built-in seals on their ends, in lieu of the small '0' rings previously fitted.
Remember that many of the '0' rings used on Boxers are of fluroelastomer material, and if overheated will produce hydroflouric acid this very unpleasant substance will pass through your skin, and progressively rot your flesh. Always handle any decomposed rings (eg: from a fire-damaged motorcycle) with caution, using rubber gloves and tweezers. Wash the area with plenty of water before handling. If you are contaminated, wash thoroughly, and seek medical treatment immediately! Remember f left too long before treatment, amputation may be the only option!

A Slow Boxer is often one which has recently received new float needles, and has had its floats adjusted by the original method this latest method works for all Boxers. With the carburettor on the machine, and the float fully lifted, turn on the fuel. Slowly lower the float, until fuel just begins to flow - the metal float bridge, and the molded line on the float, should be parallel with the float chamber joint face. At this point ensure that the operating tab is at 90' to the needle. This may require re-alignment and if so, the above procedure will need to be repeated.

Does Your K-Series Battery Charge warning lamp glow slightly, particularly when the heated grips are turned on, becoming brighter with engine speed? Don't worry this is a characteristic of all K-Series models, and is due to the sum of the voltage drops across the large number of connections between the battery and warning lamp, one of which also supplies the heated grips. Without running another wire directly from the battery to the warning lamp, there is nothing which can be done about it, but at least you know the warning lamp is working!

Can't Start Your K-Series? Power for both the starter push and the clutch switch comes from the same source fuse no.1 (instruments) which can blow due to a faulty heated grip. Later 16-valve and 1100 cc models also use a sidestand switch, which is not above suspicion.

Don't Leave Your K-Series idling while you don your helmet, or have a last cigarette at idling speeds the mixture strength is dependant solely on temperature, and can be very rich on a cold winter's morning. Just start up and ride away!

Does Your K-Series Oil Level Rise? Strange as it sounds, a faulty fuel pressure regulator can pass petrol directly into the rear throttle body in sufficient quantity to pass the piston rings and enter the sump! This only takes place at high vacuum levels, and cannot be seen at idle

Older Boxers are fitted with resilient mounts for their rectifiers (diode boards) which can fail, short-circuiting the battery cable against the inside of the front engine cover. This can be both exciting and expensive, so check regularly and change these mounts every few years.

The Alternator Excites through the battery charge warning lamp, and if this circuit is broken by a faulty bulb, the alternator will not self-excite until about 5,000 rpm. Always check that the alternator warning light is on when you first switch on. It should be completely extinguished by 2000rpm.

Low Alternator Voltage can often be traced to an inaccurate voltmeter - always have yours checked against a known good meter before starting to worry about the various expensive possibilities!

Battery Charge Warning Lamps which do not go out can cause some worrying, but always remember that if you reduce the load to ignition only, the battery will run the engine for most of the day. Carry some lightweight jump leads, which will enable you to recharge from a friend's machine, and most of your immediate problems will recede if you have a faulty charging system.

K-Series Trafficator Switches operate by connecting to earth, so if your trafficators will not operate, check that the 'Cancel' switch is not earthing, or if one side operates continuously, check that its switch is not earthed. The easy way is to unplug the appropriate switchgear cluster, before checking further with a test meter.

The 'Soldered' Joints within a Boxer wiring harness are actually crimped, and it has been found that after about ten years, particularly on the R45/65, water has collected inside the outer sheath and corroded the crimps. The resultant copper-based slurry will conduct, but at higher currents the voltage drop can be enough to cause strange problems, such as total power loss, with the engine stopping, when main beam is selected. Should this occur at night it could be very interesting!

Fork Seals Fail Regularly on pre-1984 Boxers are not fitted with fork gaiters. The fitting of these useful items is easy enough. You need 2 gaiters and 4 clips. If so protected, your fork seals will last almost indefinitely.

Petrol Cap Jammed? This is not uncommon on older Boxers, the cap spinning round but not unscrewing! It can be removed without damage to paintwork by standing on the footrests, and passing a rope through the filler cap handle; tie it into a loop around your shoulders, and heave - the whole cap will pop out easily.

K-Series Valve Clearances do not need adjusting very often - check them about every 30,000 miles or so, and remember that removal of the cambox cover deprives the cams of the oil baths in which they normally rotate. Coat each cam with grease before replacing the cover, using new seals in all positions.

K100 Silencer Stuck? Apply some heat from a blowtorch (having first removed the petrol tank), and then allow some engine oil to soak in for a while. Repeat the procedure, and twist the rear of the silencer, pulling to release the silencer from the pipes. Apply Optimol TA anti-sieze grease before replacing. Replace the clamps in their original positions, and remember to fit the tongues of the clamps into the cut-outs in the silencer stubs before replacement.

K-Series and the Twins post '81 Swinging Arm Bearings may be 'sealed for life', but they can be unsealed and greased easily. Using a pointed scriber, open the bearings by attacking the outer seal from its inner edge, and the inner seal from its outer edge, after which fresh grease can be worked through the bearing, and the seals replaced.

K-Series Fixed Swinging Arm Pivots are usually very tight, and many are damaged during extraction. Carefully use a small blowtorch to warm the gearbox casing around the pivot (having first removed the petrol tank), and lever it out with small tyre levers (BMW ones are ideal). The cause of this problem is usually corrosion on the pivot pin. Remove the corrosion with emery tape before greasing and replacement.

Radiator Fans can become stiff through lack of use, so after winter lay-ups always turn the fan by hand before starting the engine. A seized fan can be the cause of a very expensive overhaul I!

Older K100's Seem to Get Very Hot before their fans cut in, due to different engine thermostat settings, so if you have doubts, check with a good thermometer before buying new sensors etc. The fan should cut in at 103'C, before the warning lamp operates at 111'C.

Starting a K-Series with a flat battery can not only cause the ABS unit to register a power supply problem, but can also cause more severe problems - as the starter contactor coil will operate at reduced power, its contacts will not be held together tightly, and arcing will result. In extreme cases, the contacts can become welded together, making the starter motor run continuously - it's cheaper to buy a BMW power socket, through which you can keep the battery fully charged.

Battery Charging via the BMW power socket is recommended by the manufacturer, subject to a limit of 4 amps. Remember that batteries give off Hydrogen while on charge - do not smoke, or use naked lights in their vicinity!

A BMW Voltmeter left in situ can make a good diagnostic tool, if it is connected via a small jack socket; insertion of a test lead will then reconnect the meter to the test lead, and you can check all manner of circuits with it, except the alternating current output of the alternator at the red, yellow, and blue wires. If you are going on a long run, carry a small multimeter.

Boxer Voltage Regulators can fail, but are easy to check - just unplug the unit, and connect the blue and black wires of the plug together while the engine is running. If the alternator voltage increases sharply, the voltage regulator was faulty. On the older electromechanical type, the internal contacts are sometimes the culprit, and can be cleaned, but the solid state units must be replaced.

If Your Battery Fails to Charge, always ensure that the alternator brushes are making good contact with the sliprings, that their holder is clean, and 12 volts can be measured at the brush connected to the black wire. Should this not be so, the voltage regulator or connecting wiring should be examined. If 12 volts is present, lift the 'brown' brush with a piece of cardboard, and measure for 12 volts at its slipring - if this not is present, the rotor windings will be faulty. Remove the cardboard, and measure at the 'brown' brush - if this does not read zero volts, its earthing is faulty. If these tests are in order, use a multimeter to measure the AC output of the alternator at the red, yellow, and blue wires - if 12 to 14 volts AC is measured here, but the battery voltage does not rise at higher engine speeds, the rectifier (diode pack) is at fault, and must be replaced.

When Replacing a Diode Board, remember that the black wire should be connected to the starter motor solenoid. Many owners connect this to the most obvious place - the spare terminal at D+ on the back of the Diode Board! In such a case no harm will have been done, but the starter motor will not operate. Both terminals on D+ are connected to the same place, and either can be used to connect the blue wire. Remember also that the earth cable must be connected from the negative heat sink - off one of the upper securing bolts - to a clean area of aluminium, thinly coated with Vaseline.

The LE-Jetronic Injection system, as used on the K75 and K100, is probably the most reliable piece of the machine, and many apparent problems can be traced to low fuel pressure. Should your K splutter to a halt, always open the filler cap, and turn the ignition on to check that the fuel pump is running - if not, check the fuel tank connector behind the RH side panel, and then the fuel pump relay in the housing below the tank, and its fuse. Other possible causes of fuel starvation are the pump pick-up filter screen (Remove the pump to see it) and the fuel filter - if you have had any water in the tank, it may be choked, as it will not circulate water. Remove the filter, and join the pipes together until you can obtain a new filter. (Ideally, always carry one!)

A K-Series Which Will Not Exceed 50 mph or so is not fun, and the answer could be that the throttle switch is jammed, so telling the injection unit that the throttle is closed; in this case, it will shut off the fuel supply above engine speeds of about 3,000 rpm.

What Should You Take on a European, or other long tour? The means to stay mobile is paramount - a BMW pump, tubed and tubeless tyre repair kits (with tyre levers), followed by inner tubes (even if you have tubeless tyres), and a small tin of instant tyre repair. On the electrical side, lightweight jump leads, plug leads, spare bulbs (mandatory in most countries) and fuses, are a good start. Always take some stiff wire, nuts and bolts, and nylon cable ties, and PVC tape. Most European states require a first-aid kit, with rubber gloves for use in Aids-concious Germany. The level of spare parts is up to you, but a fuel filter (for K- Series) clutch and throttle cables, spark plugs, and contact breaker points (if required) is a good basic level. Remember that engine oil is very expensive in Europe. Some people carry spare coils, voltage regulators, alternators, etc! Whatever you take, know how to use them! The best insurance to take is a reliable motorcycle and a Moto-Bins catalogue. Remember we are always ready to despatch parts anywhere in the world. We can arrange very fast overseas delivery often within a day or two.

Stow Your Pump on Monolever models inside the top frame tube but always slide it in with the valve end first (handle last) and secure a piece of string or wire around the valve end for easy removal. Make sure the pump works well, oil its spindle, and, on twin-shock models, seal the handle to the pump body to prevent the ingress of water and grit from the rear wheel.

Dripping Carburettors? Float Needles should be replaced every ten years or so, as their rubber tips eventually harden, resulting in that well-known 'dripping carburettor' problem.

Needle Jets become worn as the needles vibrate within them, so passing extra fuel, and increasing your fuel consumption. The needles also wear, particularly the later brass types if in doubt, change them. The replacement interval varies with the average engine speed, being about 15,000 miles for the lower-geared models such as the R45/65, to 35,000 miles on the lazier large-capacity types such as the R100 series.

Cold Starting Problems can often be cured by replacing your old float chamber gaskets unless they provide a really air-tight seal around the choke fuel pick-up tube, the fuel level in the auxiliary chamber will not be raised, and the cold start mixture will not be further enriched during initial operation. The Auxiliary Carburettor itself can often become loose, so being by-passed and ineffective; the resultant air leak will also promote 'surging' at about 40 mph on a small throttle opening change the gasket every few years, and make sure the screws are really tight.

Wheel Bearings are probably the most neglected part of any motorcycle, and on the older, twin-shock Boxers the near-side bearing in the rear wheel can totally fail with little warning. Its seal becomes worn by exposure to grit, allowing road grit and water to contaminate the grease. The off-side bearing is well protected within the hub, and like the front wheel bearings, gives little trouble. Always remove the inner races of your bearings every year or so, washing out all the old grease, and re-packing before replacement with new seals. If you ride throughout the winter, re-grease the near-side rear bearing in Autumn and Spring. Remember - new seals are cheaper than bearings! The front wheel bearings of the later Monolever Boxers and K-Series models give little trouble, even after extreme use.

Steering Head Races on R45/65, R80ST models can often suffer premature failures, their outer races showing regular dark lines where their rollers have made contact. These lines are the sign of electrical erosion, probably due to tracking across the tachometer's ignition coil connection on the printed circuit board to the steel case of the instrument. Make sure that you earth the upper fork yoke to the main frame earth below the fuel tank, to provide an alternative path.

Alternator Brushes leave a conductive residue across their holder, so gradually diverting current from the rotor. At the end of every summer, clean the holder by pushing a piece of card below the brushes, and sliding it across the base of the holder until clean. Brushes usually last for about 20,000 miles on smaller models, and 40,000 on the larger types.

Alternator Trouble. Your friendly RAC man may be able to obtain a new rotor for you, but he will not have the extractor bolt required to remove the old one - they are cheap, and easy to carry, so don't go on a long trip without one!

Does your old Boxer feel like an old dog? Fear not - it may just be asking for some attention to the preload settings of its wheel, swinging arm, and steering head bearings. A day spent setting up these bearings is a day well spent!

Rear Crankshaft Seals are easy enough to change, but it is also easy to damage your internal crankshaft thrust bearing in the process. Before attacking the flywheel bolts, always locate the crankshaft fully backwards. This will prevent the crankshaft from being forced forwards when the seal is levered out, or the flywheel is replaced. Remember - a damaged thrust bearing will require a full engine strip to replace!
On post-'81 Models, remove the crankshaft end cap by levering under the groove around the centre boss - use small tyre levers supported over the cap. Remember to replace the '0' ring inside the cap, or inside the flywheel on pre-'81 engines. Before fitting the latest-type seal (the type without a spring-loaded lip) always soak it in thin oil for 2 hours, and carefully work it to form a tube which will fit over the nose of the flywheel or crankshaft end cap, as appropriate.

Rear Wheel Drive Splines on twin-shock Boxers can sometimes resemble ratchet teeth! Don't let this expensive malady happen to yours - clean and lubricate them regularly with LM 47 Spline Lubricant, and recoat lightly every time the wheel is removed.

A Worthwhile Winter Job is to remove your gearbox to clean and lubricate the clutch splines and pushrod - with OPTIMOL T WHITE PASTE.

Pre-Paralever K-Series machines can often suffer from an accumulation of water inside the swinging arm, which usually enters via the joint face between the final drive and swinging arm. This water will eventually contaminate the grease on the splines of the drive shaft, which can result in a very expensive failure of the drive shaft, and sometimes also the final drive pinion shaft. Remove the final drive every year, pull the drive shaft out, and recoat the splines with Optimol T White Paste. When replacing the final drive, coat the joint faces with a non-setting jointing compound such as Blue Hylomar.

Paralever K-Series owners should also grease their drive shaft splines at least every 20,000 miles with Optimol T White Paste.

R100GS Owners should also check their drive shafts regularly - every 10,000 miles remove the front gaiter to check the drive shaft coupling, and slowly rotate the rear wheel to inspect all the needle rollers of the coupling for wear. They have worn through the coupling yoke before the owner is aware of a problem! Remove the rear gaiter, and check the other coupling, then work a little Optimol PL White Paste into the splines, and bounce the suspension to draw it in.

K-Series Clutch Release Arms pivot on a pair of needle rollers, which are usually attacked by water thrown off the rear wheel. Replacement is easy enough, but prevention is better - drill and tap a hole for a grease nipple in the flat area behind the pivot, and cross- drill a 2mm hole from its base to pick up the pivot bore between the bearings.

Stainless Steel exhaust pipes turned brown? They can easily be cleaned by use of Wonder Wheels wheel cleaner, followed by Solvol Autosol.

Batteries will generally last for years, if taken care of. Fit a BMW-type power socket, and connect a constant-voltage battery charger when the bike is not in use. Remember that the resilient mounts under the battery carrier also deteriorate, and replace them every 6 to 8 years. The golden rule is never to leave your BMW with a flat battery. If you let this happen, the plates will irresversibly sulphate. This applies equally to new or old batteries alike.

Exhaust Valves have a definite life, after which they are liable to lose their heads, with terminally expensive consequences for the piston and cylinder head! The R45/65 valves, with their 7mm stems, can fail after 35,000 miles, while the 8mm stem valves fitted to the larger models should last for 50 to 60,000 miles. Prevention is cheaper than cure!

Exhaust Port Nuts on all Boxers should be removed and all threads coated with fresh Optimol TA anti-seize grease every year. With a cold engine, slowly pour a kettle of boiling water over each nut before removal. If this fails, drill a row of 2mm holes along the nut, and split it off with a chisel - new nuts cost a lot less than reclaiming a damaged thread! Tighten fully.

Cylinder Base Oil Leaks on Boxers often come from the pushrod tube grommets - use of the special tool, which can easily be manufactured, and a sharp tap with a two-pound hammer will usually effect a cure.

Petrol Taps require lubrication too! It's amazing how easily they operate after being stripped, cleaned, and their indexing plates greased.

Neutral Switches are easy to change, in spite of their location, although many 'professionals' have charged customers for gearbox and swinging arm removal! Just support the back of the engine, remove the rear mounting stud, and knock out the long aluminium spacer. Remember that the /6 and /7 Series switches are different, and don't forget to drain the oil first!

BMW HT Leads are of excellent quality but no HT lead last forever. On the Twins they are exposed to extremes of temperature as well as all that the elements can throw at them. If tracking from the HT terminal to the steel shroud takes place, massive power losses can occur, particularly at large throttle openings. Remove and clean them regularly. If tracking cannot be cured, replacement is necessary life. We recommend replacment of the twins HT leads every 5 years.

One of the Few unreliable parts on a BMW is the early type of double-ended ignition coil found on the post-1981 R45/65, R80GS, and all Boxers from 1984 to 1992. These coils - usually with grey cases and Bosch part no 0.221.500.200 will let you down sooner or later! The usual symptoms are ignition failure in wet weather, poor cold starting, and intermittent failure. Check the plastic case for signs of cracking, and be ready to buy a new-type coil, particularly if a long trip is to be undertaken. Better still, buy a new one now! New type coils have Bosch no. 0.221.500.203.

Black Box Failures of the Bosch electronic ignition system are rare, but intermittent failure can be caused by overheating. The unit is seated onto its heat sink with a thin coat of white heat transfer paste, which gradually dries out. Remove the unit every ten years or so, clean both surfaces, and apply a thin coat of paste, which is available from most electronics suppliers.

Early (pre-1981) R45 and R65 models can fracture their front coil bracket - as this carries the main earth connections a total electrical failure will follow, which can be dangerous at night! Fit an extra earth cable between the coil bracket earths and the main frame.

Gearbox Oil Going White? Emulsified oil is a symptom of water being absorbed, and in the case of Boxer gearboxes it usually enters along the outside of the speedo cable. Fit a new boot and grease the cable/gearbox contact points and your troubles will be over.

Big Ends' Gone? It's probably only a noisy timing chain, particularly on post-1979 models with a single-row chain. The chain will become noisy after 30,000 miles, but the original tensioner blade does not provide any tensioning after initial wear takes place. Fit the latest, all-plastic type, and live in peace with your Boxer! At high mileages this is also a good opportunity to replace the spring in the oil pressure relief valve, and check that its piston is seating correctly.

Can't Get the Dip Stick in? On pre-1979 Boxers the oil pump pick-up strainer can split at a spot weld, and a vibration-induced crack can spread across a securing bolt hole. The strainer can then become loose, and pivot across the dip stick entrance. It can also cover the pick-up hole, so don't delay your examination!

When Removing a Clutch Plate, it is a good time to carefully fill the ignition timing marks with white paint, to improve their visibility. In the interests of personal safety, always use the correct tools to decompress pre-'81 Boxer clutch spring. On post-'81 Boxers and K- Series models, progressively unscrew the 7mm socket screws in a diagonal pattern. Be prepared to replace them, and always change their shafeproof washers.

When Replacing a Boxer Timing Chain, mark the sprockets with paint, as the timing mark on the crankshaft sprocket is hidden by the outrigging bearing.

Gearbox Bearings are a very tight fit on their shafts, so when fitting replacements, heat them to 200'C. When removing layshaft bearings, which are very close to the adjacent gearwheels, start them on their way by carefully levering with small tyre levers - the BMW type are ideal. Pull off the large bearing at the front of the output shaft by engaging the legs of the puller below the adjacent fifth gear wheel. Heating the Gearbox End Cover makes it easier to replace.

Intermittent Loss of Fifth Gear is not unknown, and is usually due to the cage of the front output shaft bearing having broken up, allowing the balls to crowd to one side, and the shaft to move outwards under load. Continued riding in the lower gears is possible, but can promote rapid wear.

Loss of Gear Selection is caused by fracture of the small spring which holds the positive stop link up against the camplate pins. It is possible to invert the entire machine, in order to select third gear, and ride home with that... really - it has been done!

Jumping Out of Gear can be a symptom of the camplate indexing roller having broken up, or its spring having broken - a gearbox strip is the only answer to these problems.

Front Engine Covers on post-'78 Boxers are usually difficult to locate on the pin at the bottom - drill out the hole in the cover to be a free fit, and remember to grease the pin. Before removing or replacing the cover, disconnect the battery to prevent a short from the positive side of the Diode Plate.

Silencer Mounting Bolts on twin-shock Boxers usually strip their threads after about ten years - it is possible to tap their captive nuts to M8, but more reliable to fit longer stainless steel bolts with nylon nuts behind the brackets.

ATE Front Brake Adjustment on pre-'81 Boxers can be difficult - make sure that the caliper pivot spindles rotate freely in their bushes, and in the calipers. After adjustment, don't forget to check the adjustment of the master cylinder operating arm.

R100RS and S Models with a Brembo rear disc can present a struggle when it comes to wheel removal, if the caliper bracket is seized onto the spindle - remember to grease the bush in it's centre, or even fit a grease nipple. Likewise, remember to remove and grease the bolts on the torque stay, so that you can undo them by the roadside.

Pre-'81 Boxer Centre Stands can give trouble, mainly due to their pivot bolts becoming loose, wearing the threads in the frame lugs, and twisting them. In most cases such damage can only be repaired by welding and re-threading, or drilling out and manufacturing stepped pivot bushes, neither of which is easy with the engine in position. Make sure that your bolts are tight, and the stand is well-lubricated.

All tubular BMW Centre Stands eventually suffer from wear and rust, particularly the K-Series - an internal application of anti-rust wax will prevent corrosion, and wear at the contact spot can be stopped by avoiding 'riding' the bike of its stand while carrying your weight particularly against the front brake. If badly damaged from either source, a new stand is the only real answer. The single skinned K-series stand can also suffer from weld penetration and exterior corrosion, so check yours now. Consider replacing with the later K Centre Stand from the 16 Valve series which is a much better design (we do not know of a failure yet!).

Wobbly Side Stands, usually on Boxers, can be a real problem, particularly on a well- laden bike. The cause is wear in the 'ears' of the stand, and can be repaired by welding or replacement - in either case, ensure that the frame lug is not also badly worn, as this is difficult to repair with the bike the right way up. If necessary, fit a thin washer to make up the clearance. Prevention is better than cure - oil the pivot regularly, particularly in winter. Consider replacing the stand with a 'surefoot' stand. It may well be the cheapest cure.

Removing Your Engine? The long mounting studs can be very tight - if so, do not try to drift them out with a hammer, but apply penetrating oil, place packing pieces (large nuts or piles of washers) below the one nut, and tighten it to pull the stud out as far as possible; add more packing, and continue, using tube spanners and packing if necessary. If necessary, heat the surrounding metal with a blowlamp. Grease the studs before replacing them or play safe and replace with stainless steel studs.

Replacing Steering Head Races? The outer race (the one in the frame) can be very awkward to remove, there are three basic ways. The first is using the correct BMW tool (which can be hired from the BMW Club). The second is to drill two small holes in the frame so a punch can be inserted, and knock the bearing out. The third is to apply two small beads of electric weld to the race; the contraction of the weld is usually enough to loosen the race. Don't try to drive the stem out of the lower fork yoke after heating it up, as is usually advised. The stem is not shrunk into the yoke, but is pressed, cutting paths for its fine splines as it does so. Unless suitable tools are available to press it in and out (replacing it in the same position, to ensure that the steering lock will engage in the usual place) it is preferable to grind away the inner race of the lower bearing until it can be split off with a chisel. Heat the new inner race to 200'C.

R45/65/65LS/80ST Owners - would you like another gallon or more of fuel, a little protection for your knees on cold days, and two fuel taps so that going onto reserve is not like turning the ignition off. Fit a standard R100GS fuel tank - it fits perfectly, but is an inch shorter than the standard tank, so the seat will require some modification, but it is well worth it, particularly for the short-armed!

Commuting on a Boxer with a dipped headlamp can leave you with a flat battery after a week or so - maybe less if you have a small battery - but a good answer is to use a 20 watt halogen bulb in the pilot lamp position. The 20 watt bulb is as bright as a headlamp, but does not dazzle other drivers. RS and RT owners will need to connect the existing (but unused) holder in their headlights to the parking lamp circuit. We also recommend replacing the standard voltage regulator with the higher output one. This is done by the Police because of all the extra electrical equipment on their BMW's.

Ignition Advance Units can become sticky with age, their springs then being unable to fully return the bobweights, causing a fast idle and low-speed pinking. Many owners have found these problems recur soon after cleaning and lubrication, the problem being that the 'lubrication' was with WD-40, the limited lubrication properties of which soon evaporate with heat! Always use a thin engine oil, don't forget the bearing between the cam and its spindle, and, in the case of all post-'78 models with the 'beancan' enclosure, the outrigger bearing above the points, or Hall Effect trigger, as appropriate.

Does Your Boxer Neutral Lamp Flash when the clutch is disengaged? This means that the diode in the starter relay circuit has failed, and is short-circuited. The diode is built into the contact plate at the back of the headlamp shell (all twin-shock models except R45/65), contained within a black plastic cylindrical housing, plugged into the wiring below the starter relay (pre-'81 R45/65), or contained within the starter relay (all post-'81 R45/65 and Monolever models).

Can't Start Your Boxer in Neutral? If you can only start by disengaging the clutch, but everything seems to work as it should, the starter relay diode has failed, becoming an open circuit, and must be replaced, as above.

Monolever Series Lights (from 1987) can all come on when the starter is operated, or when 'P' is selected at the lighting switch! In either case, the culprit is one of the two tiny diodes inside the Lighting Relay - replacement of the individual components is a job for an expert, so if in doubt replace the relay.

Poor Pick Up of Bing CV carburettors can often be traced to blockage of the two pick-up orifices sited at the base of the carburettor body, on the engine side of the throttle plate; clear them with a piece of thin wire or better still, a 'Primus' blowlamp pricker.

High Fuel Consumption on Boxers can be due to the atomising air supply being blocked by sludge blown out of the crankcase breather into the inlet elbows. Examine the pilot air jet (the brass jet is at the lower inlet end of the carburettor), the atomising orifices in the upper part of the pilot jet, and those on the mixing chamber which surrounds the needle jet; while doing this, blow through the associated air galleries from the inlet end of the carburettor.

Do Not Try to replace the needle jets of Bing CV carburettors while they are still mounted on the engine! The needle jets and mixing chambers will fall out easily enough, but the needle jet cannot be centralised properly by pushing it up from the bottom of its bore. In such circumstances, any attempt to tighten the main jet holder will result in a bent needle, or even a split carburettor body. Take the carburettor off, and invert it to fit these items.

Easy Cold Starting, immediately followed by cutting out, can often be caused by a partially-choked cold starting jet. These jets are fitted in the bottom of the float chamber, at the base of the auxiliary chamber from which the starting carburettor draws its fuel. Their purpose is to restrict the rate of fuel flow immediately after a cold start, so automatically weakening the mixture. Should even one become partially blocked, that cylinder will not continue to run when cold and the engine will usually stop. Remove and clean these jets, particularly if the float chamber shows signs of corrosion due to water ingress etc.

A Fire Risk has existed on RS and RT models for years, where the lateral fairing bracket passes below the fuel tank. The captive nut on its frame clamp has sharp edges, and the main battery cable is usually pressed against it, just above the engine. Several machines have burnt out from this cause, and it is virtually impossible to realign the battery cable. Either insert a piece of rubber sheet over the cable, or do it properly, and exchange the positions of the battery cable and the adjacent small auxiliary cables.

Early /5 and /6 Series models have a headlamp flasher which is unfused, and live at all times. It has caused the odd fire - usually when unattended and should either be reconnected to the fused ignition circuit, or fitted with its own fuse.

Flooded Your K? The electronics will always provide enough fuel for a cold start, but supply of a matching quantity of air is up to you! In very cold conditions always hold the 'choke' at full travel, and if necessary open the throttle a little also, but be ready to shut it when the engine fires. Lots of failed attempts to start will flood the engine and wet the plugs, so don't rely on just tweaking the throttle a bit for cold starting!

Can't Get At Your K75/100 Battery? The instructions in the manual are not too good; remove both side panels, and pull out the plastic pin on the offside of the injection unit. Pull the unit out to the nearside, until the multi-pin socket is visible - you will then be able to see the retaining spring clip, and lever it away from the socket, which can then be removed. The plastic tool tray holder can then be pulled out between the frame tubes.

Remember to Change your brake fluid every year or so it's easy, even on a K with ABS. As well as keeping your brakes in top form, it will remove water and debris, so preventing future problems, and maintain full braking efficiency. Always use DoT4 specification fluid, which maintains a higher boiling point when contaminated by water than does DoT3.

Rear Crankshaft Seals on pre-1978 Boxers were originally white in colour, and deeper than the later black seal. The white seal is now unobtainable, and when fitting the later seal in an early crankcase, take great care that the seal is not driven in as far as it will go, so that its lip is in the same position as was the original - measure from the crankshaft thrust bearing, which is visible behind the seal, and make very sure that the seal is square with the crankshaft axis. The best answer is to fit the seal on top of the special spacer ring which is available from BMW Owners Club for this very purpose!

Poor Pick-Up in Boxers is often traced to blocked pick-up orifices; this pair of tiny holes are sited in the bottom of the main venturi passage of the carburettor just on the 'downstream' side of the throttle plate. Make sure that they are clear by use of a Primus blowlamp jet pricker or similar.
Oil on a Boxer Clutch is not necessarily a sign of a failed rear crankshaft seal - it is more likely to be caused by a failed '0' ring at the end of the flywheel bore, or on post '81 models inside the flywheel cap. This ring prevents oil pressure from the rear main bearing creeping between the flywheel (or cap) and the tail of the crankshaft, so exiting around the flywheel bolts. Always change this o-ring when removing the flywheel.

Loss of Clutch Adjustment on pre 81 twins, can be attributed to the clutch release bearing failing. Early replacement is the only answer, as swarf from the bearing can get into the gearbox. When replacing lubricate the bearing well, and ensure that there is free play between the actuating arm on the back of the gearbox and the pushrod. Check this freeplay regularly as clutch wear reduces the play.

Removing Rocker Arm Bearings, to remove the rocker arm bearings, select a washer slightly smaller than the outside diameter of the bearings, then using a long bolt and a spacer or socket draw the bearings out.

Fitting New Piston Rings. On all boxer engines, never fit an oil control ring gap facing down, as when the engine is stopped after a run, oil can collect in the bores and seep through the end gap. Also remember to separate the three gaps to 120'.

Removing a Gearbox when removing a gearbox from a 2 valve twin, there is no need to remove the engine, just disconnect the swing arm and move it rearwards, remove the battery carrier and remove the clutch arm, this should give you enough room to remove the gearbox.

Brass Fairing Rivets rather than attempt to peer over the brass rivets on RS and RT screens with a hammer, just insert a BA screw through the centre of the rivet then a washer and nut, tighten the nut, the action of which will peer over the end of the rivet.

Replacing Tank Badges rather than gouge your paint work removing your old self adhesive tank badge with a screw driver, simply cut it off using dental floss, by inserting the floss behind the badge and work the floss backwards and forwards with a sawing action.

Pinking Problems when setting the ignition timing on all two valve boxers always check it with a strobe on the max advance mark, in many cases it will be over advancing due to wear in the ATU unit, thus causing the pinking. If this wear is not excessive retard the ignition slightly to align the marks.

Contaminated Clutch Oil on a Boxer Clutch is not necessarily a sign of a failed rear crankshaft seal - it is more likely to be caused by a failed ‘O’ ring at the end of the flywheel bore, or on post - ’81 models inside the flywheel cap. This ring prevents oil pressure from the rear main bearing creeping between the flywheel (or cap) and the tail of the crankshaft, so exiting around the flywheel bolts. Always change this o ring when removing the flywheel

A NOTE OF CAUTION ON THE 8 VALVE BOXER TWINS Oil on a Boxer Clutch is not necessarily a sign of a failed rear crankshaft seal - it is more likely to be caused by a failed ‘O' ring at the end of the flywheel bore, or on post - '81 models inside the flywheel cap. This ring prevents oil pressure from the rear main bearing creeping between the flywheel (or cap) and the tail of the crankshaft, so exiting around the flywheel bolts. Always change this o ring when removing the flywheel