How do I look after a motorbike over winter?

The three things that actually damage a stored bike, whether to SORN or keep it taxed, and how to bring it back in spring without a workshop bill.

Difficulty: beginner
Time: 1 hr
Read: 6 min
Safety: caution

Short answer

Three things do the damage: a discharging battery, fuel degrading in the tank, and moisture corroding everything it touches. So: put the battery on a smart maintenance charger, fill the tank with fresh fuel and add a stabiliser, clean and dry it thoroughly and protect the metal, keep it under a breathable cover somewhere dry, and take the weight off the tyres. If it is off the road, a SORN saves the tax — but reduce the insurance rather than cancelling it.

A bike does not deteriorate in winter because it is cold. It deteriorates because it stands still, damp, with a slowly discharging battery and a tank of fuel that is going off. Every one of those three is straightforward to prevent and expensive to fix afterwards. The classic spring bill — a dead battery, gummed carburettors, seized brake calipers and a corroded chain — is entirely the result of an autumn afternoon that did not happen. The other decision is whether to lay the bike up at all, because a UK winter has plenty of dry cold days and a bike ridden occasionally is in far better health than one that has not moved since October.

Safety

Never run an engine in a closed garage — carbon monoxide is odourless and kills quickly. Store fuel only in approved containers and never inside a home. Keep a battery on charge in a ventilated place, not in a sealed cupboard, and never charge a battery that is swollen, cracked or leaking. Make sure the bike is on secure, level ground on a paddock stand or a properly located centre stand before working on it.

Step by step

Decide whether you are laying it up or riding through.Riding through means salt, and salt is the single worst thing for a motorcycle — it gets everywhere and corrodes fasteners, wheels and the frame. If you ride in winter, wash the bike after every salted ride and protect the metal. If you are laying it up, do it properly rather than half-heartedly.
Clean and dry it thoroughly before storage.Wash off road salt and grime, and then get it genuinely dry — a ride to warm it through, or compressed air, works better than a cloth. Dirt holds moisture against metal all winter. This is the step that does the most and gets skipped the most.
Protect the metal.A corrosion inhibitor spray on the unpainted metal, the fasteners, the fork stanchions and the exposed engine cases. Keep it off the brake discs, the pads and the tyres. Chain lubed after cleaning, and the chain adjusted correctly before it stands.
Sort out the fuel.Fill the tank right to the top with fresh fuel — an empty tank sweats and rusts from the inside — and add a fuel stabiliser, following the dose on the bottle. Petrol containing ethanol absorbs water and degrades over months, and it is particularly hard on older bikes with carburettors and on rubber fuel lines.
Look after the battery.This is the most common single failure. Either remove the battery and keep it somewhere cool and dry on a smart maintenance charger, or leave it in place with an optimiser connected through the bike's accessory socket. A lead-acid battery left to self-discharge over a winter sulphates and often will not recover.
Take the load off the tyres if you can.Paddock stands front and rear are ideal. Failing that, over-inflate slightly and move the bike a few centimetres every few weeks so it is not standing on the same patch of rubber all winter. Flat spots from months on cold concrete are real and are permanent on older tyres.
Cover it, but let it breathe.A breathable motorcycle cover in a dry garage. Do not use a plastic tarpaulin or a sheet of polythene, which traps condensation against the bike and corrodes it faster than leaving it uncovered. If it must live outside, a proper outdoor cover with vents, and lift it occasionally to check underneath.
Decide about tax and insurance.If the bike will genuinely be off the road on private property, a SORN removes the tax liability and stops the direct debit, with remaining full months refunded. Do not cancel insurance entirely — a bike in a garage can still be stolen, and most insurers offer laid-up or reduced cover. Theft from garages peaks in winter.
Bring it back carefully in spring.Check tyre pressures and condition, check the brakes are free and the discs are not heavily corroded, check the chain and its adjustment, check all the fluids and the lights, and take a gentle first ride on quiet roads. Both your reflexes and the bike's brakes need a few miles to come back.

Common mistakes

Storing it with a nearly empty tank — The empty space fills with damp air that condenses on the tank walls and rusts them from the inside. Full to the top with stabilised fuel leaves no room for that air.
Cancelling the insurance while it is in the garage — Theft from garages and outbuildings peaks in winter and a laid-up bike is a stationary target. Reduced or laid-up cover costs far less than cancelling costs if it goes.

If it doesn't work

Battery dead in spring and will not take a charge

Cause: Sulphation from months of self-discharge — Fix: Usually terminal. A smart maintenance charger over the winter costs a fraction of a replacement battery and is the single highest-value thing in this guide.

Runs badly or will not start after standing

Cause: Degraded fuel, or varnish in the carburettors — Fix: Drain and refill with fresh fuel first. On a carburettor bike the float bowls may need draining and cleaning, which is why stabiliser and a full tank matter so much on older machines.

Brakes binding or a caliper seized

Cause: Corrosion on the pistons and sliders after standing damp — Fix: A garage job on anything safety-critical. Prevent it by storing the bike dry and, if you can, giving the brakes a gentle exercise every few weeks.

Chain has surface rust

Cause: Not lubricated before storage, or damp storage — Fix: Clean and lubricate properly. Light surface rust usually cleans off; a chain that has seized links needs replacing along with the sprockets.

Corrosion under a plastic cover

Cause: Condensation trapped against the metal — Fix: Use a breathable cover. A plastic sheet in an unheated garage produces a small greenhouse that is wetter than the air outside.

Bike stolen from a garage over winter

Cause: Winter is peak season for motorcycle theft from storage — Fix: Ground anchor and a good chain, an alarm or tracker, and do not cancel the insurance. Keep the garage door secured properly — the catalogue has a guide on that.

Questions people ask

Should I start it up occasionally over winter?

Only if you can get it fully up to temperature, which usually means actually riding it. A brief start in a garage does more harm than good: it puts moisture and unburnt fuel into the oil and the exhaust without ever getting hot enough to boil them off, and it takes a big slug out of the battery.

Do I need to change the oil before storing it?

It is worth doing if the oil is near the end of its interval. Used oil contains acidic combustion by-products which sit against the internals all winter. Fresh oil going into storage is a small job with a real benefit on an older engine.

Is a SORN worth doing for a few months?

If the bike is genuinely off the road on private property, yes — the tax stops, remaining full months are refunded, and it is free to declare. Remember it must be on private land, not on a public road, and you must tax it again before riding.