The expensive surprises on a used motorcycle are rarely the engine. They are the consumables that are technically still working: a chain at the end of its adjustment, tyres that are legal but five years old, brake pads at a third and fluid that has never been changed, and a battery that will start the bike on a warm afternoon and not on a cold morning. Each one is individually modest. Bought together, immediately after purchase, they can add a meaningful fraction of the bike's price. Learning to read remaining life rather than pass or fail is what separates a fair price from a bad one.
Chain and sprockets, and the adjuster trick
Look at the chain adjuster marks on the swingarm before you look at the chain. If the axle is sitting near the end of the adjustment range, the chain has already been stretched about as far as it can be taken up, and a new chain and sprocket set is due now rather than later. Sellers know this, which is why the adjuster position is a better tell than the chain's appearance.
Then check the chain itself in three ways. Grip a link at the rear of the sprocket and pull it away from the teeth: if you can lift it far enough to see daylight under the tooth, the chain is worn out. Rotate the wheel slowly and watch for tight spots — a chain that goes slack and then taut as the wheel turns has uneven wear and cannot be adjusted correctly at any setting. And look at the sprocket teeth in profile: new teeth are symmetrical, worn teeth curl over into a hook shape, and a hooked rear sprocket will destroy a new chain quickly, which is why chains and sprockets are replaced as a set.
Free play should be set to the figure in that model's handbook, measured at the point the manual specifies and with the load the manual specifies, because the correct number varies widely between machines and a chain set by feel is either eating itself or loading the output shaft bearing. Our chain maintenance guide covers the method; the number itself comes from your owner's manual, not from us.
Tyres, where age beats tread depth
Tread depth is the check everyone does and the least informative one. A used bike usually has legal tread. What it often also has is tyres that were manufactured years ago, and rubber hardens with time and heat cycles regardless of mileage. The date is on the sidewall: find the DOT code and read the last four digits as week and year, so 2621 means the twenty-sixth week of 2021. The US Tire Manufacturers Association explains the sidewall markings and the general position on tyre ageing, and most manufacturers publish their own age guidance in the owner's handbook.
Then read the shape of the wear rather than the amount. A rear worn flat in the middle with unused edges is a motorway bike. A front with cupped scallops on the leading edge of each tread block has done a lot of braking on a bike with tired fork damping — the tyre is a symptom and the forks are the cause. Different brands front and rear is not automatically wrong, but a mismatched pair on a sports bike usually means someone replaced one tyre as cheaply as possible. Our guide to reading tyre wear patterns goes through what each shape says about the previous owner.
Check the pressures with your own gauge before the test ride, and check them again cold. A bike that has been sitting with both tyres well under the placard figure has probably been standing for months, which is information about far more than the tyres. Riders who want to stop guessing fit a Bluetooth TPMS sensor and read pressures on the dash; our explainer on how motorcycle TPMS works covers what the systems can and cannot detect.
Brakes, where the cheap part hides the expensive one
Pads are cheap and easy to see through the caliper. Discs are neither. Every disc has a minimum thickness stamped on it, usually near the hub, and a disc measured below that figure is scrap regardless of how it looks. You need a micrometer to check properly, which is one of the reasons a workshop inspection earns its money on a machine near the top of your budget.
What you can check without tools is the lip. Run a fingernail from the outer edge of the disc towards the centre: a pronounced ridge where the pads have never swept means significant material has gone. Look at the pad backing plates for uneven wear between inner and outer pads, which points to a sticking caliper piston or a seized slider. Look at the caliper pistons themselves for corrosion or a crusty ring where they emerge from the seals.
Brake fluid is the item most often ignored on a used bike. Conventional glycol-based fluid absorbs moisture from the air over time, which lowers its boiling point and eventually corrodes the system from inside, and that happens whether the bike is ridden or parked. Most manufacturers specify replacement on a time interval measured in years rather than on mileage — check the interval in the handbook for that model. Fluid the colour of dark tea in the reservoir sight glass tells you the interval has been missed. Brake work is the clearest example of a job to hand to a technician if you are not confident, because an air bubble in a motorcycle front brake is not a cosmetic error. The motorcycle crash research collected by the Insurance Institute for Highway Safety is a reasonable starting point on why braking performance is treated as a primary safety system rather than a convenience, and it is the right frame for a machine whose maintenance history you have just inherited.
Battery, charging and the cold-morning problem
Batteries are where sellers and buyers most often talk past each other. A lead-acid battery that has been repeatedly discharged and left flat loses capacity permanently through sulphation, and the failure is gradual: it cranks fine warm, marginally when cold, and then not at all on the first frost. Shops commonly see three to five years from a conventional battery in regular use, and much less from one that spent winters flat.
The static check is the date sticker and the terminals: white or green crust at a terminal means it has been leaking or overcharged. The functional check is cranking speed on the cold start, which should be brisk and even rather than laboured. If the seller says it needs a jump start, treat the battery as a replacement item and price it, but also ask whether the charging system was ever tested, because a bike that eats batteries usually has a regulator or stator fault, and that is a much larger bill than a battery.
A bike that spends winters on a maintenance charger like the MT100 bi-directional charger comes out of storage in a different condition from one that does not, and a seller who mentions unprompted that they kept it on a charger is telling you something useful about how the rest of the bike was treated.
What is left, and what it will cost you
| Item | How to judge remaining life | Typical replacement trigger | Where it sits on the cost scale |
|---|---|---|---|
| Chain and sprockets | Adjuster position, lift at the rear sprocket, tight spots, hooked teeth | Axle near the end of adjustment, or any hooked tooth | Moderate, always replaced as a set |
| Tyres | DOT date code first, then depth and wear shape | Age beyond the manufacturer's guidance, squared profile, cupping | High, and usually needed as a pair |
| Brake pads | Visible material against the wear line through the caliper | Below the wear indicator, or uneven inner to outer | Low per axle, but often both ends together |
| Brake discs | Minimum thickness stamp, plus lip at the outer edge | Measured below the stamped minimum, or warped | High, often the largest single consumable cost |
| Brake fluid | Colour in the sight glass and the last service record | Time interval in the handbook, regardless of miles | Low, and frequently overdue |
| Battery | Date sticker, terminal corrosion, cold cranking speed | Slow cranking cold, or any history of being left flat | Low to moderate, but check the charging system too |
| Fork seals and oil | Oil ring on the stanchion, damping behaviour on the ride | Any weeping seal, or a front that dives and bounces | Moderate, and higher if a stanchion is pitted |
| Coolant and hoses | Colour and level in the expansion tank, hose feel when cold | Time interval, discolouration, hoses gone hard or spongy | Low, but a neglected system points at wider neglect |
| Air filter and spark plugs | Service record, plus a look if access is easy | Interval in the handbook | Low, high value as an indicator of how it was owned |
| Valve clearances | Service records only, since you cannot see them | Model-specific interval, often long and often skipped | The one that can dwarf everything else on this list |
Adding it up honestly
Write the list before you talk money and be realistic about which items are genuinely due now. It is tempting to add up every consumable at full replacement cost and present it as a discount demand, and sellers see straight through that. The credible version is narrower: items at or past their replacement trigger, priced at what a workshop would charge, presented as a list rather than as a single number.
The trade-off worth naming is that a bike with everything worn out is not automatically a worse buy. It is a cheaper buy that comes with a known, bounded programme of work, and you end up with fresh consumables you chose yourself. The genuinely bad buy is the machine where consumables have been renewed cheaply and recently to make a sale — budget tyres, a no-name chain, pads of unknown origin — because you inherit those choices at a price that assumed quality parts. Given the choice between a tired bike with documented history and a freshly tidied one with none, experienced buyers take the tired one.
One category deserves separate treatment: valve clearances. They are invisible, model-specific, sometimes very expensive on engines that need the cams removing, and they are the item most often skipped by owners who otherwise maintain a bike well. Ask for the record and the reading at which it was done. No record on a machine well past its interval is not a deal-breaker, but it belongs in your arithmetic, and the interval itself comes from that model's official service schedule. Our wider cost of ownership guide puts these consumables in the context of the annual running cost, and the inspection checklist is the sequence to run them in.
FAQ
How do I know if a motorcycle chain needs replacing?
Check where the axle sits in the adjustment range, try to lift a link away from the rear sprocket, and turn the wheel looking for tight spots. Any of those failing means a chain and sprocket set, and they are replaced together because a worn sprocket ruins a new chain.
How old is too old for motorcycle tyres?
Read the DOT date code rather than the tread. Manufacturers publish their own guidance and it appears in the owner's handbook, but rubber hardens with age and heat cycles regardless of mileage, so a tyre with plenty of tread and several years on it is still a purchase you will be making soon.
Does brake fluid really need changing on a bike that is barely ridden?
Yes, and arguably more so. Conventional brake fluid absorbs moisture from the air over time, which lowers its boiling point and corrodes the system internally. That is why the interval is stated in years rather than in miles.
Is a motorcycle that needs a new battery a bad buy?
Not on its own — a battery is a modest cost. What matters is why. Ask whether the charging system has been tested, because a bike that repeatedly kills batteries usually has a regulator or stator problem, and that is a much larger bill than the battery it hides behind.
Should I walk away from a bike with no valve clearance record?
Not automatically, but price it. On some engines the check is a short job and on others it means removing the cams, so look up the interval and the labour reality for that specific model before deciding what the missing record is worth in the negotiation.
