Motorcycle won't start after sitting all winter

Symptoms

• Bike started fine before storage but won't now
• Fuel in the tank has been sitting for months
• Battery wasn't maintained with a tender during storage

Likely causes

• CommonDead or severely discharged batteryBatteries self-discharge over months of storage, especially without a maintainer connected.
• CommonStale fuel that's degradedGasoline, especially ethanol blends, breaks down and can gum up carburetors or injectors after months.
• CommonGummed-up carburetor jets from varnishSmall carburetor passages clog easily with residue from evaporated stale fuel.
• PossibleCorroded battery terminals or connectionsTerminals can corrode during storage, especially in humid environments.

What to do

1. Charge the battery fully with an appropriate charger before attempting to start, since a weak battery alone can prevent starting even with everything else fine.
2. Check the fuel; if it smells stale, varnish-like, or has been sitting more than a few months without stabilizer, drain the tank and carburetor and add fresh fuel.
3. Clean battery terminals of any corrosion that built up during storage.
4. If it still won't start on fresh fuel and a charged battery, the carburetor jets are likely gummed up and need cleaning, which is a common post-storage repair.
5. Check the spark plug for fouling from old fuel attempts to start, and clean or replace it if needed.
6. For fuel-injected bikes, stale fuel is less likely to clog injectors but can still cause rough running; consider a fuel system cleaner additive.

Tools and parts

• Battery charger
• Basic hand tools
• Fuel-safe drain pan

When to call a pro

If cleaning the carburetor is beyond your comfort level, a motorcycle shop can do a full post-storage service including carb cleaning and a tune-up.

Safety