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Okay to Leave Motorcycle in Rain? (Read this first)

Acid rain is eating my pride and joy. I can’t bear to watch…it’s too painful!

Leaving your motorcycle in the rain won’t damage it. Motorcycles are weatherproof. However, continuous outdoor wet weather will shorten the life of some of the electrical components.

In this post, you’ll learn the effects of parking your bike in the rain, and you’ll also learn practical ways to help guard against wet weather use.

Motorcycle on wet Dublin street

A Little Rain Won’t Hurt

Moisture generally is the enemy of all machinery. If allowed, it causes corrosion anywhere there’s metal. The trapped moisture finds a weakness in components and paintwork and starts to eat your bike.

This doesn’t happen overnight, but it may only take a few weeks of sitting in the rain to see the results.

Parking your motorcycle in the rain generally won’t hurt it. The best thing you can do is to ride it. Getting the engine to operating temperature dries out the components, and when the bike is parked under shelter, the residual heat from the engine will drive out any trapped moisture.

Longer-term outdoor storage will, however, cause a ton of annoying issues, especially if you’re not riding the bike and getting that engine hot.

Components at risk include:

  • Ignition system
  • General electrical system
  • Fuel system
  • Brakes
  • Bodywork

The two systems most affected by moisture are the ignition system, and fuel systems.

Ignition System

The ignition system of your bike produces the high voltage needed to fire the spark plug. Although robust, they won’t tolerate moisture. The components are mostly weatherproof, but condensation has a real knack for penetration.

Symptoms of a wet electrical system include:

  • No start after wetting
  • Misfiring
  • Backfiring
  • Stalling
  • Erratic idling
  • Hesitation and stammering

Main ignition system components include:

Stator – Located behind the engine side cover, it produces the voltage needed to run the motor and charge the battery. It’s low down, and although sealed, water can get inside and short out the coils.

Bike Pickup coil

Pickup coil – The pick-up is a sensor located at the crankshaft and signals the CDI box to fire the spark plug via the coil.

CDI – The CDI box runs the show, and although it’s a solid-state unit, and is pretty durable, moisture around the block connector contact points can cause corrosion.

Motorbike CDI box

Not all bikes have a CDI box fitted. More sophisticated higher-end models are fitted with an ECU, which is a computer-controlled ignition and fuelling system not unlike a modern car.

Dirt bike coil

Coil – The coil converts low voltage to high voltage and supplies the spark plug via the plug wire and cap. The coil, coil wire, cap, and plug are the components most affected by trapped moisture.

Spark plug The plug as you know is the business end of the spark.

And it is the component most likely to cause a no-start and should always be checked early in the game of troubleshooting no starts or poor running such as lack of power, poor fuel economy, erratic idling, etc.

Spark plug gap ATV and Dirt Bike

Charging system

Rectifier and regulator – The rectifier/regulator is not part of the ignition system but it has a part to play in the production of voltage needed to run a bike. The regulator is responsible for converting the stator’s a/c voltage into usable d/c voltage and charging the battery.

Dirt bike rectifier

Trapped moisture inside the regulator block terminal may promote pin corrosion.

Fuel System

As you know, water and gas don’t mix at all. Water in the gas tank will eventually make its way to the carburetor. Fuel filters will only remove grit from fluids. They won’t prevent water from passing through.

Symptoms of water in the gas:

  • No start
  • Hesitation
  • Flat spots
  • Bogging
  • Wont idle
  • Stalls
Dirt bike carburetor bowl drain

If you suspect water in the fuel system, draining the fuel bowl (Carburetor models) will fix the issue.

Motorbike Bodywork

Bodywork will suffer too, rain damage won’t be immediate, but years of constant exposure will cause clear-coat and paint coatings to break down. Hard-to-reach places often trap muck which also holds moisture close to the bodywork.

These areas will be attacked first, as they’ll trap road salts and moisture, a perfect combo for corrosion.

How to protect bodywork:

Clean thoroughly even the hard-to-reach places, don’t allow muck build up. Only wash your bike using auto detergent. Using household detergent will strip away protective wax coats.

When the bike is clean, use a touch-up paint stick to protect any broken paint. Use a top-quality wax-like Knubea. Waxing once a quarter will keep your paintwork protected from road salts and rain.

Use DuPont Teflon spray coating on plastics, rubber components, and hard to wax areas. The coating prevents crap from sticking. Dirt that does stick walks off when washed. It causes rainwater to bead and run from the surface. It’s easy to use and non-oily.

Motorbike Storage

You already know a bike likes that lives indoors, in the long run, will be cheaper to maintain, be more reliable, live a longer life, and will have a higher resale value.

I’ve been a mechanic for twenty years, I can spot machinery that lives outdoors from across the street, and working on them isn’t fun. Even the smallest job can be a struggle. Outdoor kit degrades and fasteners seize and break making even the simplest jobs a struggle.

Not everybody has a garage, I understand. But if you can, even some basic shelter will help and garaged or not all bikes should have a cover.

A plastic sheet won’t work, that compounds the moisture problem. It locks it in. A good quality waterproof breathable cover is the best option. They might cost a few dollars but guaranteed they’ll save you money in the long game.

A full gas tank helps prevent condensation from forming inside the tank. Less surface area equals less condensation.

Gas stabilizer

All road-going vehicles must use ethanol-blended gas. Most people don’t realize they’re using it.

Blended gas attracts moisture and can go stale in as little as a month. I use a gas stabilizer mixed with the gas to help keep it fresh and reduce moisture contamination.

You may find these posts helpful also:

How often should I start a motorcycle?

Can you run a motorcycle without a battery?