Everything else in this book answers a question you already know to ask. This chapter is for the questions you do not — the order to do things in, the habits that save a weekend, and the mistakes that are common enough to have names.
None of it is difficult. Airheads were built to be maintained by their owners, with hand tools, at the roadside if necessary. What catches people is sequence: the right job done in the wrong order wastes a fortnight and teaches you nothing.
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 book| Order | Do this | Where | Why first | |
|---|---|---|---|---|
| 1 | Find out exactly what it is | VIN, model, and which side of 9/80 | Every parts order and half the specifications hang on the autumn 1980 divide. Establish this before you buy a single component, not after the wrong one arrives. | |
| 2 | Compression test | both cylinders, wide open throttle | Twenty minutes that tell you whether you are doing maintenance or a rebuild. Do this before spending money on anything else — it changes what the rest of the list is worth. | |
| 3 | All fluids out | engine, gearbox, final drive | You do not know when they were last changed and the seller does not either. Cheap, and the state of what comes out is free diagnosis. | |
| 4 | Valve clearances | cold, both sides | The most common neglected job and the one that quietly destroys cams and seats. Also your first look inside the engine. | |
| 5 | Charging system check | resting volts, then running volts | Two meter readings. An airhead that will not charge strands you, and the fault is usually cheap if you find it before the battery is cooked. | |
| 6 | Ignition timing | strobe, idle and full advance | Do this before touching the carburettors. Most “fuelling” complaints are timing complaints wearing a disguise. | |
| 7 | Brake fluid and fork oil | both legs, matched | Age-based jobs, not mileage-based. Fluid that has sat for a decade has absorbed water whether the bike was ridden or not. | |
| 8 | Driveshaft splines | inspect and lubricate | The expensive airhead failure that gives almost no warning. If there is no record of it being done, assume it has not been. | |
| 9 | Now, and only now, the carburettors | sync, then mixture | By this point a genuine carburettor fault is the only thing left standing. Start here instead and you will chase symptoms for months. |
| Tip | Detail | Applies to | Notes | |
|---|---|---|---|---|
| Photograph everything before you touch it | phone, from several angles | especially cable and hose routing | every job | Free, takes seconds, and repays itself the first time you cannot remember which way the throttle cables crossed. Routing is the thing nobody remembers and no manual shows clearly. |
| Do not destroy what you have not yet replaced | label, do not cut | wiring especially | rewiring, upgrades | Borrowed from motogadget's own installation guide and it applies far beyond wiring. Keep the old system intact and identified until the new one has proven itself running. |
| Bag and label per assembly | one bag per component, written on | not one tray for everything | any teardown | Fasteners on an airhead are not interchangeable as often as they look. The bag that says “left rocker” is worth more than a good memory three weeks later. |
| Both sides, always the same | symmetry beats absolute values | forks, carbs, clearances, timing | boxer twins | A boxer tolerates being slightly off spec far better than being different side to side. Matched-but-imperfect runs smoothly; perfect-on-one-side does not. |
| Buy the gasket set before you start | and the seals you might need | not after the engine is open | any internal work | A bike in pieces waiting on a two-pound part is how projects die. Order the consumables with the tools. |
| Anti-seize changes torque | a lubricated thread pulls tighter | at the same wrench reading | exhaust, fasteners | Published figures assume a stated thread condition. Use anti-seize where it belongs, but know you are no longer reading the same number — see . |
| Replace circlips and crush washers | never reuse | pennies each | everywhere | A reused circlip has already been sprung once. This is the cheapest insurance on the entire bike. |
| Write down what you did | date, mileage, what and why | on paper, kept with the bike | forever | You are also the next owner's documentation. A bike with records sells for meaningfully more, and you will not remember which gear oil you chose in three years. |
| Avoid | Because | Instead | Notes | |
|---|---|---|---|---|
| Rejetting to fix a running problem | the commonest airhead mistake | it is usually timing, valves or an air leak | work the order above | Jet kits sell well because the symptom presents at the carburettor. Confirm compression, clearances, timing and intake sealing first — the jetting was probably right when it left the factory. |
| Pulling the flywheel or clutch carrier without blocking the crank | stated flatly by Snowbum | no exceptions, any model | holding tool — | A thirty-five dollar tool against damage you cannot buy your way out of quickly. |
| Trusting one manual's number | the manuals contain known errors | including reversed instructions | cross-check — | Where two sources disagree this book says so rather than picking a winner. Treat any single figure that seems wrong as probably wrong. |
| Over-torquing into aluminium | forty-year-old castings | threads pull out, cases crack | torque wrench — | “Good and tight” is how helicoils get sold. The published figures are lower than instinct suggests, and instinct is wrong. |
| The “while I am in there” spiral | scope creep finishes more projects than rust | one job becomes eleven | finish, ride, then start again | A running bike you keep improving beats a perfect bike you never reassemble. Set the boundary of the job before you start and write it down. |
| Leaving ethanol fuel in the tank | over a long lay-up | attacks old lines and liners, absorbs water | drain, or use stabiliser | The tank interior and the fuel lines on a bike this age were not designed around modern pump fuel. |
| Mixing brake fluid types | DOT 5 silicone into a DOT 4 system | not compatible | A conversion is a complete strip and flush, not a top-up. | |
| Buying on cosmetics | paint is the cheapest thing to fix | splines and compression are not | test what is expensive | A tidy bike with unknown splines and low compression costs more than a scruffy one with records. Judge the bike by items 1, 2 and 8 above, not by the tank. |