Chapter XX
Written & Filmed Guides
Every figure on this page resolves to one model and year in the book. Pick your bike and the rows that apply to it come forward, with the rest marked.
Open this chapter in the bookNumbers tell you the target; video tells you what the job actually looks like — how hard the feeler drags, which way the circlip fights you. These are the airhead-specific series worth your time, linked rather than embedded so they stay current and the app stays offline-capable. Boxer2Valve sells downloads of their episodes — worth buying before a job if the garage has no signal.
The full rebuild series
| Series | What it covers | | Depth | Notes |
|---|
| Boxer2Valve — R90/6 tutorials | front to back, 23+ episodes | William walks a forgotten airhead back to life | the reference series | Ep 5 clutch, gearbox seal & install · Ep 6 final drive reseal · Ep 7 swingarm bearings, rear brakes · Ep 8 wheel bearings, driveshaft bolts · Ep 9 exhaust, heads, cylinder reseal, valve adjustment · Ep 10–11 engine electrics, timing cover, timing chain · Ep 23 tank, points, carb sync, test ride.
Series index |
| Airhead Mechanicals | episode-based procedures | downloadable for offline | procedure-focused | #6 Bing carburettor recondition · #11 timing, carb sync, valve adjustment & first service |
| Dispatch Moto — R75/6 rebuild | full build series | candid, modern | watching a rebuild land | Valve adjustment & the issues it exposes |
By job — jump straight to it
| Job | Watch | | Chapter | Notes |
|---|
| Valve adjustment | all models & years | R80/7 shown | | The procedure is identical across R50 through R100. Airhead valve adjustment (all models) · alternate on a /2: R50/2 procedure. The clearances for your model and year are in — set them cold. |
| Bing carb rebuild | every step, 32 mm shown | applies to 40 mm | | R90/6 Bing carburettor rebuild — long, but nothing skipped. Pair with the CV metering plate. |
| Timing & carb sync | points, timing, balancing | R60/5 shown | | Airhead timing & carb synchronisation. Points-era; '81+ Hall systems skip the gapping. |
| Points, tank & final sync | fuel valves through test ride | R90/6 Ep 23 | · | Fuel valves, tank, points, carb sync & test ride |
| Final drive reseal | disassemble & reseal | R90/6 Ep 6 | | Watch before opening yours — re-shimming triggers are covered in the chapter. |
| Swingarm & rear wheel | bearings, brakes, driveshaft bolts | R90/6 Ep 7–8 | · | Note the U-joint bolt rule: Blue Loctite, never lockwashers. |
| Timing chain | cover off, chain replacement | R90/6 Ep 10–11 | | Duplex to '78, single-row from '79. |
The procedures below are the outside reading and viewing behind How-to, by job in My Bike: for each job, the written procedures by the recognised airhead specialists and the filmed ones from the workshops that teach. Every link was opened and read when it was added; what it covers and why it is worth your time is described in this guide’s own words. The specialists do not always agree with each other — where they differ on a number, the disagreement is noted rather than hidden.
Procedures — Just bought it — the first weekend
| Source | Kind | By | Applies to | What it covers |
|---|
| Purchasing an old airhead and getting started | read | Snowbum (Robert Fleischer) | all airheads | What a used airhead really costs to put right, why you should do the maintenance yourself, and a graded path from cables and washing up to real repairs. The most honest expectation-setting a first-time buyer will read. Read it → |
| Airhead maintenance schedule | read | Snowbum (Robert Fleischer) | all airheads | Interval by interval, what to inspect, lube, change and re-torque from the first weekend to 100,000 miles, with storage and record-keeping. Turns "where do I start" into an ordered list. Read it → |
| Airhead buyer’s guide | read | Air Support BMW | all airheads | A specialist shop on what to scrutinise when buying, which generations are strong or weak, and the signs of bad prior work. Short and blunt. Caveat: Model preferences are the shop’s opinion. Read it → |
| Pre-project inspection of a newly bought R100RS | read | Brook Reams | twin-shock (1983 R100RS shown) | A systematic walk over a just-purchased airhead — bodywork, wiring, engine, gearbox, brakes — noting every leak and defect, with photos. How an experienced owner looks a new bike over before turning a spanner. Read it → |
| Pre-start checklist and first engine start | read | Brook Reams | twin-shock, points ignition (1973 R75/5 shown) | Everything checked before waking a long-dormant airhead: battery, head-nut torque, clearances, points gap, static timing with an ohmmeter, cranking until oil reaches the rockers. The model of a check-before-you-ride routine. Read it → |
| Testing compression | read | Duane Ausherman | all airheads | How to take a meaningful reading on a warm engine with a screw-in gauge, expected figures by model, and what the numbers say about the top end. The five-minute check that tells you what you bought. Caveat: No leak-down procedure. Read it → |
| Tune up a BMW /5 airhead engine | read | Motorcycle Classics | /5, points ignition | An 18-step photographed tune-up — plugs, points, static and strobe timing, air filter, oil — in the order a first service should run. Caveat: Later points and Hall-ignition bikes differ in detail; pair with Snowbum’s ignition page. Read it → |
| Things to look for when buying a first airhead | read · forum | BMW MOA forum | all airheads | Experienced owners list the generation-specific gotchas — 1981–84 valve seats, Nikasil, bearings — and agree that every fluid and grease point gets renewed on purchase. Caveat: Conversational; read after the pages above, not instead. Read the thread → |
Procedures — Engine oil & filter
| Source | Kind | By | Applies to | What it covers |
|---|
| Oil and filter changes | read | Snowbum (Robert Fleischer) | all airheads 1970–95 | The full procedure including measuring canister depth and the shim/gasket/O-ring stack for cooler and non-cooler bikes, with torques and part numbers. The definitive treatment of why a wrongly assembled filter cover dumps oil pressure inside the engine. Caveat: Long and dense; read the simplified page first. Read it → |
| Oils, filters and canisters, simplified | read | Snowbum (Robert Fleischer) | all airheads | The short version: which engine, gearbox, driveshaft, rear-drive and fork oils to use, the quantities by generation, intervals, the level-plug method, and the essentials of the filter canister. Read it → |
| Oil and filter change, and the $2000 O-ring | read | Robert Fleischer for the Airheads Beemer Club | all airheads | Why the large white O-ring is the part that keeps oil pressure in the engine, the correct order of filter, shims, gasket and O-ring, and the banjo-bolt and cooler variants. Easier reading than the full page. Read it → |
| Airhead oil filters and related parts | read | Anton Largiader | all airheads | The three filter-cover designs — flat, recessed, oil-cooler — with a picture of each stack. The fastest way to identify which stack your bike needs. Read it → |
| Oil filter canisters and white O-rings | read | Anton Largiader | all airheads | Measuring canister depth and working out the shim combination for correct O-ring squeeze, with the early sharp-edged versus late smooth canisters. The arithmetic behind the shimming, so you can check your own. Read it → |
| Replace the oil pan gasket and clean the oil pickup | read | Brook Reams | twin-shock, shallow pan (R75/5 shown) | Dropping the sump, cleaning the pickup screen and faces, and torquing the pan bolts in stages with an inch-pound wrench. The sump-off half of the oil job that most guides skip. Read it → |
| R100/7 oil filter change, a pictorial | read · forum | BMW MOA forum | 1977-on without oil cooler | Step-by-step photos of draining, removing the cover, setting the O-ring and shims, fitting the filter and priming before the first start. Caveat: Non-cooler bikes only; cooler models need the bleed step in Snowbum’s page. Read the thread → |
| R90/6 episode 14 — master cylinder and oil pan | watch | Boxer2Valve | twin-shock (/6 shown) | Oil pan removal and gasket replacement, deeper-sump options and filter installation, filmed in a specialist workshop. Caveat: The first half is the under-tank master cylinder; skip ahead for the oil. Watch it → |
| Changing the engine oil and oil filter | watch | Airhead Maintenance 101 | twin-shock (1976 R90/6 shown) | Short, beginner-level footage of the whole oil and filter change on a real bike, part of a five-video maintenance series. Watch it → |
Procedures — Valve adjustment
| Source | Kind | By | Applies to | What it covers |
|---|
| Setting and adjusting valves; rocker arm end play | read | Snowbum (Robert Fleischer) | all airheads; pre-1985 and 1985-on rocker blocks | Finding TDC on the right cylinder, the clearances, then aligning the rockers and setting end play — with the different methods for bushed, needle-bearing and 1985-on shimmed blocks. The one source that treats end play as part of the valve job. Read it → |
| Valve adjustment procedure | read | Duane Ausherman | twin-shock /5, /6, /7 | A former dealer’s routine for positioning the engine, checking rocker alignment and end play, and setting clearances. Frames the check as a reading to log over time, which is what catches receding seats early. Read it → |
| Valves, guides, seats and noisy valves | read | Snowbum (Robert Fleischer) | all airheads; 1980–84 seat issue | Why valve noise is usually rocker end play, the 1980–84 seat-recession problem and its cure, and what a proper valve job should include. What your clearance readings are telling you, and when adjustment stops being enough. Read it → |
| Rocker arms, shafts, blocks and valve gear | read | Snowbum (Robert Fleischer) | all airheads | How the rocker assemblies are built and fail, needle-bearing maintenance, and the /5-versus-later differences that change how you adjust. Read before touching end play on an unfamiliar top end. Read it → |
| Airhead rocker arms | read | Anton Largiader | all airheads, four rocker generations | The four rocker designs, why end play matters with angled pushrods, and how each generation can be upgraded to the later, quieter type. The quickest way to identify which system your bike has. Read it → |
| Pushrod tubes and seals, valve cover studs | read | Snowbum (Robert Fleischer) | all airheads; 16 mm tubes to 1975, 18 mm after | Replacing pushrod tube seals with the cylinder pulled, sealant choices, tube sizes by year, the re-torque sequence and the valve adjustment that follows. The leak most valve-adjusters eventually have to fix. Read it → |
| R90/6 episode 9 — resealing the cylinders and adjusting the valves | watch | Boxer2Valve | twin-shock (/6 shown) | Exhaust off, cylinders resealed with new pushrod tube seals, then a full valve adjustment on the fresh top end. A specialist’s filmed adjustment that also shows the seal job it so often goes with. Watch it → |
| Valve clearance adjustment and re-torquing the head nuts | watch | Airhead Maintenance 101 | twin-shock (1976 R90/6 shown) | Beginner-level footage of the valve check with the head-nut re-torque done first, as it should be. Watch it → |
Procedures — Points, timing & spark plugs
| Source | Kind | By | Applies to | What it covers |
|---|
| Ignition: operation, timing, advance units and coils | read | Snowbum (Robert Fleischer) | all airheads; points to 1980, Hall canister 1981–95 | Points replacement and gap, advance-unit service, static and strobe timing on the S and F/Z marks, coil specifications and the Hall-element canister. The single most complete written reference for the whole ignition job across every year. Read it → |
| F, OT, S and Z — the flywheel marks | read | Snowbum (Robert Fleischer) | all airheads | What each mark means, how to verify them with a piston stop and degree wheel, and timing by piston position when the marks are missing or suspect. Settles which mark is for static and which for full advance. Read it → |
| Spark plugs, caps and anti-seize | read | Snowbum (Robert Fleischer) | all airheads; 5 kΩ caps from 1981 | Plug types and heat ranges, gap and wear limits, cap resistance by year, the reduced torque with anti-seize, and thread repair. Read it → |
| Points, condenser and coil ignition explained | read | Duane Ausherman | points ignition, /5–/7 | How coil, points, condenser and plug work together, setting the gap, and diagnosing which of the four has failed. The plain explanation that makes the timing procedure make sense. Read it → |
| Timing an R65 | read | Don Eilenberger, IBMWR | points ignition (1979 R65 shown) | Seventeen numbered steps from battery off through new points, marking the flywheel, static timing and the strobe check at full advance. Easy to follow at the bike with a timing light in hand. Read it → |
| Care and feeding of the ignition trigger unit | read | David A. Braun, IBMWR | 1981-on Hall ignition | Symptoms of a sticky advance or dead Hall transistor, testing the amplifier, and opening the canister to replace the sensor with a common part. The only detailed service procedure for the bean can BMW calls non-serviceable. Caveat: Fiddly; re-check timing with a strobe afterwards. Read it → |
| How to set points and timing | read · forum | Tom Cutter (Rubber Chicken Racing Garage) | points ignition, pre-1981 | Points gap, static timing with a test light or ohmmeter, turning the engine, and confirming idle and full-advance marks with a strobe. A respected specialist’s own write-up, short enough to tape to the bench. Read the thread → |
Procedures — Carburettors
| Source | Kind | By | Applies to | What it covers |
|---|
| Bing CV carburettors, part 1 | read | Snowbum (Robert Fleischer) | 32 and 40 mm Bing CV (early R75/5 carbs separate) | Float needle and seat, diaphragm replacement, butterfly position, top-screw types, O-rings, and an unusually detailed photographic treatment of enrichener disc and shaft orientation. The reference nearly every other carb write-up points back to. Caveat: Not a step-by-step overhaul. Read it → |
| Bing CV carburettors, part 2 — tuning, troubleshooting, jetting | read | Snowbum (Robert Fleischer) | all airheads | Hard starting, surging, float-level setting, needle and slide wear, diaphragm sealing, cable balancing above idle, and the logic of altitude jetting. Turns part 1 into a diagnostic and tuning sequence — and explains why stock jetting usually works once everything else is right. Read it → |
| Synchronising carburettors, and the tools | read | Snowbum (Robert Fleischer) | all airheads | Why sync matters, cable free play, idle speed and mixture, then cable-length balancing at 1300–1800 rpm by manometer, electronic gauge or the plug-shorting method. Insists on valves and timing first. Caveat: The plug-shorting method is not for everyone; a vacuum tool is the safer route for a beginner. Read it → |
| Bing carburettors that leak — floats, needles, seats | read | Snowbum (Robert Fleischer) | all airheads | Diagnosing overflow and weeping, the float-jiggle first aid, float weight and buoyancy testing, float-needle replacement and tang adjustment, seat replacement, GS fuel-hose foaming. The practical float procedure, from easy fixes up to seat replacement. Read it → |
| Early R75/5 Bing CV carburettors | read | Snowbum (Robert Fleischer) | R75/5 only, early 64/32 series | Why the first-generation /5 CV carbs idle badly and a nine-step sequence to fix them: slide-tube polishing, needle position, float level, butterfly fit. The only dedicated procedure for the carbs the general pages leave out. Read it → |
| Bing carburettor rebuild | read | Tom Coradeschi, IBMWR | Bing CV (not slide Bings or R90S Dell’Ortos) | A start-to-finish rebuild: removal, disassembly, cleaning, reassembly with kit parts, then vacuum-gauge sync and cable adjustment. Compact and linear — easier to follow at the bench than the encyclopaedic pages. Caveat: Older article; check part numbers with a current supplier. Read it → |
| Rebuild and refinish Bing 64/32 carburettors and Karcoma petcocks | read | Brook Reams | 32 mm Bing CV shown; applies to 40 mm | Heavily photographed teardown, varnish removal, reassembly with a kit, left/right enrichener orientation, float and throttle setup, plus the petcocks. The best photo-documented rebuild on the web, with a long reader Q&A answering the common snags. Read it → |
| Tuning 40 mm Bing CV carburettors by ear | read · PDF | Steve Doyle, hosted by bmwr65.org | 40 mm Bing CV; method applies to 32 mm | A no-tools method for idle speed, idle mixture and cable sync above idle, in small iterative steps after a warm-up ride. Printable, for riders without a manometer. Caveat: Order differs from the Bing manual, and cable sync by ear takes several passes. Open the PDF → |
Procedures — Gearbox, driveshaft & final-drive oil
| Source | Kind | By | Applies to | What it covers |
|---|
| Viscosity, GL-4 versus GL-5, and gear oil choice | read | Snowbum (Robert Fleischer) | all airheads | What the ratings mean and the settled answer on GL-4/GL-5 for airhead gearboxes and rear drives, with recommended grades and intervals. Puts the yellow-metal myth to rest with reasoning rather than assertion. Read it → |
| Oil transfer between gearbox, driveshaft and rear drive; water in the transmission | read | Snowbum (Robert Fleischer) | all airheads; /5 four-speeds and Paralever dry shafts noted | Why oil migrates between the three housings, how much is normal, how water gets in through the speedo-cable bolt and boot, and three ways to fit the boot so it stays out. Explains the puzzling level changes you meet at the plugs. Read it → |
| Oil transfer into the final drive, driveshaft and transmission | read | Duane Ausherman | /2 and /5 (1970–71 emphasised) | Gearbox level to the filler threads, a measured driveshaft fill with a funnel trick to avoid air-lock, and tracing rear-drive overfill to its three leak paths. A dealer-era mechanic’s routine for the early bikes. Caveat: Quantities differ on later models. Read it → |
| Changing the transmission oil | watch | Airhead Maintenance 101 | twin-shock (1976 R90/6 shown) | Filmed gearbox drain and refill to the level plug. Short, beginner-level footage on a real bike. Watch it → |
| Changing the driveshaft (swingarm) oil | watch | Airhead Maintenance 101 | twin-shock (1976 R90/6 shown); Paralever has no shaft oil | Drain and measured refill of the driveshaft housing — the one most owners forget. Shows where the plugs are. Watch it → |
| Changing the oil in the final drive | watch | Airhead Maintenance 101 | twin-shock (1976 R90/6 shown) | Filmed rear-drive drain and refill, companion to the gearbox and driveshaft clips. Watch it → |
Procedures — Clutch & input splines
| Source | Kind | By | Applies to | What it covers |
|---|
| Install the transmission, lube the input splines | read | Brook Reams | 1981-on | Moly paste on the input splines, fitting pushrod and throwout piston-bearing, mating the gearbox to the clutch, driveshaft bolt torque and the clutch arm. Shows exactly what to grease and what not to — the point most spline jobs get wrong. Caveat: The driveshaft bolt torque is estimated by feel there; use a wrench. Read it → |
| Remove, refurbish and install the clutch | read | Brook Reams | pre-1981 clutch (/5, /6, /7) | Releasing the diaphragm spring safely with three long bolts, measuring spring height, inspecting plate and ring, reassembling with dowels for alignment and cross-torquing. The clearest photographed pre-1981 clutch job, home-made tooling spelled out. Read it → |
| Install the clutch (1983 R100RS) | read | Brook Reams | 1981-on clutch | Diaphragm spring, plate, pressure plate and cover with the balance marks spaced, centring the plate, and torquing the M7 bolts in sequence. Pairs with the transmission pages on the same site. Read it → |
| Clutch throwout bearings and pushrods | read | Anton Largiader | 1970–99: pre-1981, 1981–87, 1988-on | How the throwout mechanism works and which bearing, piston and pushrod each generation uses, with photos and part numbers. Sorts out which parts a given year actually has before you order. Read it → |
| Throwout bearing replacement | read | J. R. Buchanan, IBMWR | /5 shown; differences through 1981-on noted | Removing the clutch arm and pivot, extracting piston, bearing and thrust washer, cleaning, inspecting and regreasing — with the gearbox left in the frame. The one job here that does not need the transmission out. Read it → |
| Airhead spline lube, step by step with photos | read | webBikeWorld | 1986 R65 Monolever and 1984 R100RS twin-shock shown | Tank and airbox off, swingarm pivots out, gearbox back off the input shaft, clean and grease, back together, with time estimates. A plain-language owner’s account covering both layouts. Caveat: Follow Snowbum or Reams for the grease choice and quantity. Read it → |
| Airhead Mechanicals 02 — main seal, oil pump and clutch | watch | Boxer2Valve | 1981-on | Filmed replacement of the 1981-on clutch with the rear main seal and oil-pump cover done at the same time, with a parts list. Doing the seal and O-ring while the clutch is out is the standard advice, and this shows all three together. Watch it → |
| R100 spline lube, part 1 of 4 | watch · series | Chris Harris | R100 twin-shock | A working mechanic’s real-time footage of the gearbox-back input-spline job on an R100, in four parts. Watch part 1 → |
Procedures — Wheels, tyres & the rear end
| Source | Kind | By | Applies to | What it covers |
|---|
| Servicing tapered wheel bearings | read | Snowbum (Robert Fleischer) | 1970–84 tapered bearings; 1985-on sealed bearings noted | Cleaning, greasing, spacer fitting and setting preload on the tapered wheel bearings, by the shake test and by the string-and-scale method. The most complete write-up on the pre-1985 bearing stack, and why preload is measured rather than guessed. Caveat: Snowbum and Ausherman disagree on how light the preload should be. Read it → |
| Replace wheel bearings and set preload | read | Brook Reams | 1970–84 tapered-bearing wheels (1983 R100RS shown) | Pulling old races, fitting new tapered bearings with the Cycle Works tool and dialling in preload with shims and a spring scale, front and rear. Heavily photographed with an embedded video. Read it → |
| The /5 wheel bearings | read | Duane Ausherman | 1970–84 twin-shock | Diagnosing factory over-tightened bearings with the shake test and servicing them, with the explanation that it is the hub, not the bearing, that preload protects. Dealer field experience on what actually fails. Caveat: Favours a looser setting than the factory figure. Read it → |
| Swingarm adjustment | read | Duane Ausherman | twin-shock /5, /6, /7 | Installing, preloading, centring and greasing the twin-shock swingarm, freeing seized lock nuts, and centring the driveshaft in the housing. The clearest statement of the centring-and-preload logic, from someone who did hundreds. Read it → |
| Install the swing arm and rear drive | read | Brook Reams | twin-shock (1973 R75/5 shown) | Centring the swingarm with calipers, torquing the pivots and lock nuts, fitting the driveshaft coupling bolts, rear-drive gasket and boot. The actual torque sequence and measured gaps, with photos. Read it → |
| Final drive — reseal and assess | read | GFP Motorrad | twin-shock final drives (1972 R75/5 shown) | Stripping a twin-shock final drive, replacing seals, judging the rear-wheel splines and reassembling, with backlash and lateral play explained. A thorough photographed reseal. Caveat: Cross-check any shim figures against the factory manual. Read it → |
| Paralever driveshaft geometry and U-joint inspection | read | Anton Largiader | Paralever R80GS/R100GS | Measured driveshaft flex angles on the Paralever and how to judge U-joint wear and decide on replacement. The only specialist treatment of the Paralever shaft, which fails differently from the twin-shock and Monolever ones. Read it → |
| Tyres, tubes, repairs and pressures | read | Snowbum (Robert Fleischer) | all airheads | Tube and tubeless mounting, repair and balancing, and the reasoning on pressures for modern tyres and on curing thrumming or vibration. Explains why the 1970s placard pressures are too low for current rubber. Caveat: Principles rather than a single figure per model — the pressures table above is that. Read it → |
| R90/6 episode 8 — rear wheel bearings and driveshaft bolts | watch | Boxer2Valve | twin-shock (/6 shown), 1970–84 | Replacing and hand-packing the rear tapered wheel bearings, refitting the wheel and fitting the driveshaft bolts on camera. Watch it → |
| Airhead Mechanicals 09 — swingarm bearings, rear wheel and brakes | watch | Boxer2Valve | 1985-on Monolever | Replacing the Monolever swingarm bearings, refitting swingarm, final drive, shock, rear wheel and rear brake. One of the few filmed procedures for the Monolever rear end rather than the twin-shock. Watch it → |
Procedures — Brakes
| Source | Kind | By | Applies to | What it covers |
|---|
| Brakes: ATE, Brembo, drums, bleeding, master cylinders | read | Snowbum (Robert Fleischer) | all airheads — drum, ATE, Brembo | Fluids and yearly flushing, bleeding without trapping air, overhauling the under-tank ATE master cylinder, drum and disc troubleshooting. The reference page for the whole range, including the under-tank piston setting that catches people out. Caveat: Very long; use the in-page headings. Read it → |
| Brake fluid maintenance and bleeding | read | Oak Okleshen, Airheads Beemer Club | all disc-brake airheads | Why the fluid needs changing yearly and a step-by-step flush and bleed. A short, disciplined procedure from the club’s long-time technical editor. Read it → |
| Rebuild the ATE caliper and under-tank master cylinder | read | Brook Reams | 1975–76 R75/6 single disc; 38 and 40 mm ATE pistons noted | Stripping, cleaning and resealing the ATE swinging caliper and the spine-tube master cylinder, then refitting lines and pads. Photographs of every seal and piston the text guides only describe. Read it → |
| Disassemble, inspect and rebuild Brembo calipers | read | Brook Reams | 1981-on Brembo (1983 R100RS shown) | Full teardown, inspection, painting and reseal of the twin-piston Brembo calipers, front and rear. The best-illustrated Brembo rebuild for the later bikes. Read it → |
| Install the rear disc brake system and bleed it | read | Brook Reams | 1981-on twin-shock with rear disc | Fitting the rear master cylinder, caliper and lines with torque values, then bleeding the rear circuit. Covers the rear disc, which most brake guides ignore. Read it → |
| /5 front drum brake adjustment and repair | read | Duane Ausherman | 1970–77 front drum models | Adjusting and repairing the twin-leading-shoe front drum and the rear drum: cable fitting, cam-shaft cleaning, curing squeal. The go-to for drum-braked airheads, by someone who set them up in a dealership. Read it → |
| R90/6 episode 20, part 1 — front caliper rebuild, front wheel bearings, master cylinder | watch | Boxer2Valve | twin-shock (/6) with ATE disc | Rebuilding the ATE front caliper, replacing the front tapered wheel bearings and preparing the master cylinder. Part 2 on the same site covers bleeding and cable adjustment. Watch it → |
| R80RT episode 6 — master cylinder, bleeding, front wheel bearings | watch | Boxer2Valve | 1985-on Monolever, handlebar master cylinder | Rebuilding the handlebar master cylinder, bleeding the front brake and fitting the front wheel bearings on a Monolever. One of the few filmed procedures for the later master cylinder. Caveat: Part of a conversion series; some content is cosmetic. Watch it → |
Procedures — Front forks & steering head
| Source | Kind | By | Applies to | What it covers |
|---|
| Front forks: alignment, stiction, steering head bearings, sag | read | Snowbum (Robert Fleischer) | all airheads, /5 through 1995 | Aligning the legs and triple clamps to kill stiction, adjusting and replacing the steering head bearings, setting sag. Explains that notchy steering is usually hardened grease and that alignment matters more than most owners think — before you buy parts. Read it → |
| Fork oil types and fill amounts | read | Snowbum (Robert Fleischer) | all airheads | Tables of viscosity and volume per model and fork type, with comparisons of commercial fork oils. The single lookup for a fork oil change. Read it → |
| Changing fork oil, seals and gaiters | read | Duane Ausherman | 1968-on telescopics through the twin-shock R100RS | A numbered, photographed procedure for draining and refilling fork oil and replacing seals and gaiters with basic tools. The most approachable seal-and-oil job for the early forks. Read it → |
| Rebuild the front forks | read | Brook Reams | /5–/7 forks (1973 R75/5 shown) | Complete teardown from handlebars to damper rods, seal replacement and reassembly with fresh oil. Exhaustively photographed, so every internal part and its orientation is shown. Read it → |
| Replace fork seals and slider dust covers | read | Brook Reams | 1981-on 36 mm forks (1983 R100RS shown) | Wheel and sliders off, seals and dust covers changed, refilled — on the later forks, which differ from the /5–/7 units. Read it → |
| Replace the steering head bearings | read | Brook Reams | twin-shock (1983 and 1977 R100RS shown) | Driving out the races, pressing the new inner race onto the stem, and setting preload at the stem nut. Shows the Cycle Works tooling in use and how to judge a worn race before deciding to replace. Read it → |
| Steering head bearing adjustment, 1991-on GS and R | read | Anton Largiader | 1991-on R100GS / R100R threaded-sleeve steering head | The factory tool-and-torque procedure for the late threaded-sleeve steering head, which adjusts differently from the earlier stem nut. Late Paralever bikes are routinely mis-adjusted the old way; this is the correction. Caveat: Does not apply before 1991. Read it → |
| R90/6 episode 16 — steering head bearings and fork reseal | watch | Boxer2Valve | /5–/7 forks (/6 shown) | Replacing the steering head bearings and resealing the forks on camera, after episode 15’s removal of wheel, forks and triple clamp. Caveat: Read the correction in the video description before the bearing step. Watch it → |
| R80RT episode 4 — fork seals and fork installation | watch | Boxer2Valve | 1985-on Monolever forks | Seal replacement and refitting the forks and triple clamp on a Monolever, with a comparison of early and late tube styles. Episode 3 on the same site does the steering head bearings. Watch it → |
Procedures — Charging system & battery
| Source | Kind | By | Applies to | What it covers |
|---|
| Alternator brushes, rotor and stator | read | Snowbum (Robert Fleischer) | all airheads; 105 mm /5 and 107 mm /6-on stators | Rotor and stator specs by year, brush replacement with soldering, rotor removal without damage, ohmmeter tests and slip-ring cleaning. The most complete reference on the Bosch alternator’s wearing parts. Caveat: Long and digressive; read the brush and rotor sections first. Read it → |
| Diode boards, mounts and grounding wires | read | Snowbum (Robert Fleischer) | all airheads; rubber-mount boards c.1979–93 | Testing diodes with a meter or a lamp rig, rubber versus solid mounts, the added ground straps, solder-joint failures and board replacement. Why the rubber-mounted boards fail and how to test one in place. Read it → |
| Testing voltage regulators | read | Snowbum (Robert Fleischer) | all airheads, mechanical and electronic regulators | The on-bike jumper test that bypasses the regulator, a bench test with a variable supply and lamp, and the recommended set point. The jumper test alone settles whether the fault is regulator or alternator. Caveat: Bypassing drives the alternator to full output; keep revs low and the test brief. Read it → |
| Batteries: types, initialising, charging and load testing | read | Snowbum (Robert Fleischer) | all airheads | Flooded, AGM, gel and LiFePO4 compared, filling a dry battery, charger choice, the load-test method and schedule, fitment under the tool tray. A real load-test procedure and clear cautions on lithium with the stock regulator. Read it → |
| Starter motors — Bosch, Valeo, Denso; relays and solenoids | read | Snowbum (Robert Fleischer) | all airheads; 8- and 9-tooth starters | Starter fitment across years, Bosch overhaul, Valeo nose-cone and magnet failures, solenoid repair, relay and starting-circuit diagnosis. Sorts which starter fits which flywheel before you buy. Read it → |
| Valeo starter overhaul | read | Anton Largiader | 1988-on airheads (Valeo D6RA) | Disassembly and cleaning of the Valeo starter, the detached-magnet and planetary-shield failures, and parts sources. Photo-led and concise — the standard fix for a late airhead that clicks or grinds instead of cranking. Read it → |
| Check the diode board and replace the rubber mounts | read | Brook Reams | rubber-mount boards (1983 R100RS shown) | Removing the board, ohmmeter-testing every diode, swapping perished rubber mounts for solid ones and repairing cracked wiring. A photographed step-by-step that starts from a real charging fault. Read it → |
| Install alternator, diode board and ignition sensor | read | Brook Reams | 1981-on Hall-ignition bikes, 107 mm stator | Stator, rotor, diode board, regulator sub-harness and battery cables going back together in order, with routing to avoid chafe. Caveat: Uses an EME replacement kit; the sequence is the same with Bosch parts. Read it → |
| Refurbish and rebuild the Bosch starter | read | Brook Reams | Bosch 9-tooth starter, 1977-on | Removal, teardown, brush and bushing replacement, commutator cleaning, reassembly and bench test. The clearest photographed overhaul of the pre-Valeo starter. Caveat: Confirm your flywheel tooth count first. Read it → |
| Notes on R-series charging system maintenance | read | K. W. Prager, hosted by Horizons Unlimited | R75–R100 airheads | Voltage-drop testing from diode board to battery, cleaning grounds, inspecting brushes, rotor and board. A dealer technician’s short routine built around resistance in the circuit — where most weak-charging faults live. Read it → |
| R90/6 episode 11 — timing cover on, testing the electrical components | watch | Boxer2Valve | twin-shock shown; general to all | Refitting the front cover and checking alternator rotor, stator, brushes and diode board. Filmed tests to pair with Snowbum’s written meter values. Watch it → |
| Airhead Mechanicals 07 — simplex timing chain, rotor, diode board and brushes | watch | Boxer2Valve | 1981-on simplex chain (1985 R80RT shown) | Timing chain, guides and seals on a simplex engine, plus rotor and diode board inspection, brush replacement and Hall sensor refit. The whole front-of-engine job on a late bike, in order. Caveat: Simplex only; the pre-1979 duplex is the R90/6 episode 10. Watch it → |
Procedures — Compression, heads & cylinders
| Source | Kind | By | Applies to | What it covers |
|---|
| Timing chain, guides, tensioner and sprockets | read | Snowbum (Robert Fleischer) | all airheads; duplex to 1978, simplex 1979-on | Wear diagnosis, chain and sprocket replacement, nose bearing, master-link fitting, and centring and sealing the front cover. The authoritative procedure, including the cover-centring step most people miss. Read it → |
| Camshaft, cam seals, sprockets and degreeing | read | Snowbum (Robert Fleischer) | all airheads | Cam specs by model, broken cam-tip repair, seal and sprocket replacement, follower wear and ZDDP, degreeing a cam. Explains the follower-and-oil issue that ruins cams. Read it → |
| Cylinders: bores, base shims, sealing and ring gaps | read | Snowbum (Robert Fleischer) | all airheads; iron and Nikasil/Galnikal | Measuring bore wear and taper, ridge removal, base gasket and O-ring sealing, sealants and ring end gaps. The sealing detail you need whenever the cylinders come off. Read it → |
| Top-end assembly and engine break-in | read | Snowbum (Robert Fleischer) | all airheads | Disassembly order, piston-pin handling, head gasket choice and fitting, stud and tube care, then break-in revs and oil. The reassembly counterpart to the cylinder and pushrod pages. Read it → |
| Remove the engine top end | read | Brook Reams | 1981-on shown; sequence applies to all | Valve covers, rockers, pushrods, heads, gaskets, cylinders and pistons off in order, with the mistakes to avoid. The best photographed teardown, with an embedded video of the same job. Read it → |
| Remove valves and inspect heads | read | Brook Reams | 1981-on shown; applies to all | Compressing springs and removing valves, a solvent leak test of the seats, judging guides and seats, and when to send heads out. How to find a leaking valve or loose guide at home before paying for head work. Read it → |
| Replace the timing chain, crank sprocket and nose bearing | read | Brook Reams | duplex-chain twin-shock, pre-1979 (1977 R100RS shown) | Front cover off, old chain and sprocket off, nose bearing and sprocket heated on, new chain with master link, cover resealed. Fully photographed, with parts and tool lists. Read it → |
| Replace pushrod tube seals on /5, /6 and /7 twins | read | Motorcycle Classics | twin-shock 1970–80 | Cylinder off, piston out, tubes and seals renewed, cleaned and reassembled, photographed at each step. A compact walk-through for someone doing only the seals. Read it → |
| R90/6 episode 10 — timing cover off, replace the timing chain | watch | Boxer2Valve | duplex-chain twin-shock | Removing the front cover and replacing the duplex chain and related parts. Filmed, to go with the simplex job in Airhead Mechanicals 07. Watch it → |
| Airhead Mechanicals 03 — cylinders, pistons, starter and timing cover off | watch | Boxer2Valve | 1981-on | Teardown of a late engine’s top end, starter and front cover, showing the 1981-on differences during a real job. Watch it → |
Procedures — Cables, levers & adjustments
| Source | Kind | By | Applies to | What it covers |
|---|
| Throttle controls, control cables, perch wedges and the speedo boot | read | Snowbum (Robert Fleischer) | all airheads; twin-cable throttle, 32/40 mm differences | Throttle cam and gear variants, cable care and routing, clutch lever bushings, perch wedges, speedo and tach cable faults, fitting the transmission boot. The single most complete reference on the cables and handlebar hardware. Read it → |
| Controls and cables — adjustment and replacement | read | Duane Ausherman | /2 through /7 | Handlebar castings, lever straightening, throttle and clutch cable removal and fitting, clutch adjustment, riding without a clutch cable, the perch wedge. Photographed procedures for the Magura controls on twin-shock bikes. Caveat: Pre-1978 hardware; late throttle assemblies differ. Read it → |
| Clutch cable adjustment | read | Tom Childers, IBMWR | all cable-clutch airheads (/5 shown) | Setting free play at the lever and at the gearbox arm, and checking engagement afterwards. Short, correct, and clear about the free play that saves the clutch. Read it → |
| Install carburettors, cables and air box | read | Brook Reams | 1981-on twin-cable throttle | Routing throttle and choke cables through the frame loom, the Bowden splitter, setting throttle free play and matching cable pull at both carbs. The clearest photographed explanation of the twin-cable splitter. Read it → |
| Install carburettors and cables (R75/5) | read | Brook Reams | /5 early throttle and choke layout | Assembling the /5 choke lever and cable racks, routing throttle cables past the headlight ears, and cable slack at the carbs. Covers the early layout the R100RS page does not. Read it → |
| Replace the left handlebar switch | read | Brook Reams | /6 and /7 to 09/1978 headlight-shell board | Opening the headlight, reading the circuit board against the wiring diagram, moving switch wires terminal by terminal and testing. The only clear guide to matching switch wire colours to the headlight-shell board. Caveat: Later bikes use different switches and connectors. Read it → |
| R90/6 episode 18 — handlebars, levers, grips and cables | watch | Boxer2Valve | twin-shock /5–/7 | Refitting bars, levers and throttle, then routing and adjusting the clutch and throttle cables, on camera. Watch it → |
| R80RT episode 10 — grips, controls, throttle, choke and clutch cables | watch | Boxer2Valve | 1985-on Monolever | Fitting grips and switches and replacing throttle, choke and clutch cables on a late RT. The late-model counterpart to the R90/6 cable episode. Caveat: The page title mentions wiring; the cable work is the useful part. Watch it → |
Written specialists worth reading alongside
| Source | Strength | | Format | Notes |
|---|
| Anton Largiader | airhead specialist | valve adjustment → Paralever analysis | written | Long-standing authority; already cited throughout this reference. |
| Keep 'Em Breathing | curated resource hub | links to the good stuff | index | Collects restoration write-ups and video channels in one place.
keepembreathing.com/resources |
| Chris — procedure videos | candid, easy to follow | timing, carb sync, steering head, rear main seal | video | Includes engine evaluation — useful before buying. |
Documentarians — builders who wrote it all down
| Source | What they document | | Format | Notes |
|---|
| Brook & Branden Reams | five complete rebuilds, step by step | 1973 R75/5 · 1975 R75/6 · 1977 R100RS · 1983 R100RS→RT · 1983 R80ST | written + video | The most thorough rebuild documentation on the internet, organised by BMW's own fiche headings — 11 engine, 13 fuel preparation — the same numbering this reference uses. Each project has a resource list for parts, advice and services.
brook.reams.me · YouTube channel |
| — his electrical series | circuit-by-circuit wiring | /5 · /6 · /7 (1977 R100RS) | written | Builds each circuit up one at a time rather than dropping a finished diagram on you — the clearest explanation of airhead wiring anywhere, and the right companion to before any rewire.
Airhead electrical systems |
| — his transmission write-ups | remove, inspect, refresh, assemble | shift cam, input, intermediate & output shafts | written + video | Done with a long-time airhead mechanic advising. He also points to Cycle Works' Transmission Rebuild DVD (all airheads 1955–1995) and the Moto Phoenix YouTube series “R100RS Gearbox Overhaul”. |
| — a note | the site is now Brook's & Branden's | | 2024–25 | Brook was diagnosed with ALS and can no longer ride or rebuild; his son Branden now works in the shop and continues publishing. The archive he built stays freely available — worth saying thank you if you use it. |
| Boxer2Valve | R90/6 series & parts | shop that teaches | video | See the series table above. |
| Anton Largiader | valve adjustment → Paralever analysis | | written | Cited throughout this reference. |
Manufacturer documentation & install guides
| Maker | What to pull | | Where | Notes |
|---|
| Motogadget | official install manuals | m.unit blue · m.button · m.lock · motoscope | manuals.motogadget.com ↗ | Download the PDF for every component before you cut a wire. The manuals carry the details that sink rewires: ground-switched inputs, the M5 mounting screws as the ground path, m.lock's 40 mm read distance through non-metal only, and the 2 Nm screw torque. Configuration lives in the mo.ride app over Bluetooth. |
| EuroMotoElectrics | EnDuraLast installation guide | wiring, /5 starter-relay mod | euromotoelectrics.com ↗ | Also publishes application tables — production month decides fitment. |
| Siebenrock | installation instructions + TÜV papers | supplied with every kit | siebenrock.com ↗ | Kits split at the autumn-1980 crankcase change; the paperwork matters for inspection in some markets. |
| Cerakote | C-Series application TDS | blast media, mil thickness, cure | cerakote.com ↗ | Follow the technical data sheet, not the marketing page — see Finishes & Coatings. |
| Bing Agency | official BMW CV jetting chart | every carb number | bingcarburetor.com ↗ | The source behind . |
m.unit wiring — diagrams & walkthroughs
| Source | What it covers | | Form | Notes |
|---|
| MOA thread — ’89 R100GS ↗ | full m.unit blue + m.button install | owner’s own schematic, posted | forum | The most complete airhead m.unit record in public. Clutch lever wired to the stand input so the starter will not turn without the lever pulled; kill switch cuts ignition plus the oil, generator and neutral lamps; start button double-tap disables ignition. Read the replies too — the airheads group flagged the unshielded m.button-to-m.unit run as a concern. Same builder also moved to a 600 W stator and diode board. |
| BMW R100 m.unit wiring ↗ | OEM harness to m.unit, connection by connection | the closest match to an airhead rewire | video | Start here if you are converting rather than building a loom from scratch. |
| The Moto Works — R90/6, part one ↗ · part two ↗ | m.unit and Chronoclassic together | gauge and control unit in one job | video | Two parts. Useful if the speedo is changing at the same time as the loom. |
| motogadget — wiring & installation ↗ | the maker’s own method | identifying unknown wires | guide | Multimeter on continuity, follow the cable physically, check part numbers when unsure. Their golden rule is the one worth taping to the bench: do not destroy what you have not yet replaced. Label the old cables and leave them intact until the new system has proven itself. |
| Pure Performance — R100RT rewire | m.unit + m.lock, fault-chasing | bracket, mounting, grounding | write-up | Worth it for one detail most accounts skip: earth checked with a meter from the terminal block through the unit and mount to chassis, reading 0.2–0.3 ohm. The M5 mounting screws are the ground path — see Electrical. |
A naming change to know before you order. motogadget now brands the unit mo.unit blue; older stock, forum threads and most install videos still say m.unit blue. At least one large retailer lists the m.unit blue as discontinued, which appears to be the rename rather than the end of the product — but confirm what you are buying, because the documentation splits across both names.
All-in-one control units — the alternatives
| Unit | Maker | | Position | Notes |
|---|
| mo.unit blue | motogadget | 12 inputs · 10 outputs · Bluetooth LE | the benchmark | Solid-state fusebox and relay bank in one, configured over the mo.ride app, with keyless go and live fault diagnosis without pulling the unit. 90 × 53 × 30 mm, about 180 g, 6–20 V. Two M5 screws mount it and carry the ground; one M5 post for battery positive. LIN bus for other motogadget parts. |
| Black Box V3 ↗ | Purpose Built Moto | deliberately simpler | less to configure | Built explicitly as a less complex alternative — everything you need and nothing you do not. The pitch is a straightforward install without app configuration. Choose it if you want the wiring tidied rather than the bike computerised. |
| B-Box ↗ | Axel Joost Elektronik | cheaper, upgradeable | value | Runs off a standard ignition switch as supplied, with external RFID antenna or Bluetooth available later. Sold in the UK through BSK SpeedWorks, who pair it with their K-series engine management package. |
| PC-8R and similar | power distribution modules | eight outputs · 40 A | different animal | A PDM distributes and protects circuits but does not replace switchgear logic, flasher or starter control. Worth knowing so the comparison is honest: cheaper than a control unit because it does less. |
Purpose Built Moto keep a running
comparison of control relays ↗ across makers. It is written by a competitor to motogadget, so read it as a well-informed argument rather than a neutral survey.
Builders worth following
| Builder | Work | | Where | Notes |
|---|
| Corner Custom | airhead café & scrambler builds | USD conversions, gold laced wheels, deep colour work | Instagram | Photography featured in the Build Gallery with permission. His black café with the gold USD front end is the Front-End Swaps chapter made real.
@corner.custom |
| Cognito Moto | conversion hardware + finished builds | trees, stems, hub kits | cognitomoto.com ↗ | Their build blog doubles as fitment reference. |
| Revival Cycles | resto-mods, Motogadget rewires | builder-dealer | Austin, TX | They sell what they install and support it. |
| Omega Racer | hand-formed alloy bodywork | R100-focused | specialist | Tanks, cowls, exhausts. |
Craft & inspiration — watch a master work
| Source | What you get | | Where | Notes |
|---|
| 46Works — Shiro Nakajima | ground-up builds, filmed start to finish | ~170,000 subscribers | Yamanashi, Japan | A trained engineer, racer, fabricator and furniture maker working alone in the foothills of the Yatsugatake mountains. Each video walks a stage of a build — machining parts from solid billet, bending and welding exhausts from scratch, blueprinting an engine. Almost no talking, no hype; just the work, shot beautifully. The single best thing to watch when you are stuck on your own build.
46works YouTube |
| — his R100RS restomods | a parts list worth studying | engine blueprinted to factory spec | reference build | Reads like this book's Upgrades chapter executed at the highest level: Bings swapped for Keihin FCR39 flatslides, one-off titanium 2-into-1, Ducati USD Öhlins forks with a custom stem and triples, and a Motogadget motoscope mini with mo.blaze bar-end signals. Every one of those decisions is documented in this reference. |
| — his race R75/5 | what an airhead can actually make | 85 hp at the wheel | Legend of Classic | Against ~50 hp at the crank stock. Built in three weeks, finished the day before its first race, went on to win the championship. |
| — his R75/6 | restraint as a discipline | looks stock, is anything but | study piece | The build to look at when deciding what not to change. |
| Ritmo Sereno | Japan's premier BMW restomod shop | founded by Nakajima in 2001 | Japan | He left in 2014 to start 46Works; the house style — café-clothed airheads — spread worldwide from here. |
The feature press — where builds get published
| Publication | Character | | Where | Notes |
|---|
| Bike EXIF | the standard-setter | story + build sheet + photography | bikeexif.com ↗ | If you ever submit a build, its format is the format — see the interview kit in this project's files. |
| Return of the Café Racers | builder-focused, long-form | how-to alongside features | returnofthecaferacers.com ↗ | Their front-end conversion guide informed . |
| Pipeburn | story-led features | photography decides everything | pipeburn.com ↗ | Blunt about it: weak photos, no feature. |
Community & archives
| Resource | Strength | | Format | Notes |
|---|
| Snowbum (R. Fleischer) | the encyclopedic archive | torque, carbs, charging, everything | bmwmotorcycletech.info ↗ | The backbone of this reference. Opinionated, occasionally chaotic to navigate, almost always right — and unafraid to contradict the factory manual with reasons. |
| Airheads Beemer Club | the club itself | tech days, Airmail, regional Airmarshals | membership | Tech days are the fastest way to learn — someone who has done your job is usually standing there. Worth joining before a big project. |
| Boxerworks · ADVrider · BMW MOA forums | searchable collective memory | decades of threads | forums | Search by part number, not description. Verify anything you find against a chapter here — forum torque figures drift. |
| Duane Ausherman | /5-era service material | transmission, general repair | written | Mostly /5 and the 4-speed box; cited by Brook Reams for transmission work. |
| Colorado Airhead Beemer Club | regional events | | Colorado | Example of the regional chapters worth finding near you — there is an active Northeast scene. |
| Iles Motorsports · Rubber Chicken · Long's | independent airhead mechanics | when it leaves your bench | Denver · PA · PA | The two PA shops are a day trip from central New Jersey. |
Watch, then verify here. Video shows technique; it does not always show the right number for your build date. When a presenter calls out a torque or clearance, check it against the chapter — especially anything either side of the 9/80 changeover.
Chapters