Okay to leave motorcycle in rain? (Read this first)

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

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

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


A Little Rain

Moisture generally is the enemy of all machinery, if allowed, it causes corrosion any where there’s metal. The trapped moisture finds 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 your 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 effected are moisture are the ignition and fuelling 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 weather proof 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

Your bikes stator located behind the side cover of your bike produces the voltage needed to run the motor and charge the battery, it’s low down and although sealed, water does get inside and short out the coils.

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

The rectifier/regulator which is responsible for converting the stators a/c voltage into usable d/c voltage and charging the battery may also suffers from pin corrosion.

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 effected by trapped moisture.

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 carburettor. Fuel filters will only remove grit from fluids, they won’t prevent water passing through.

Symptoms of water in the gas:

  • No start
  • Hesitation
  • Flat spots
  • Bogging
  • Wont idle
  • Stalls


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 traps muck which also holds moisture close to the bodywork.

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

How to protect:

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 coats wax.

When the bike is clean, using a touch up paint stick to protect any broken paint.

Use a top quality wax like knubea, waxing once a quarter will keep your paint work protected from road salts and rain.

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


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

I’m a mechanic for twenty years, know machinery that that lives outdoors, working on them isn’t fun. Even the smallest job can be 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.

Plastic 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 forming inside the tank, less surface area equals less condensation.

All road going vehicles must use ethanol blended gas, most people don’t realise they’re using it. Blended gas attracts moisture and can go stale is as little as a month. I use a gas stabiliser mixed with the gas to help keep it fresh and reduce moisture contamination.

John Cunningham

John Cunningham is an certified mechanic and writer on ATVFixed.com. I’ve been a mechanic for over twenty years, I use my knowledge and experience to write articles that help fellow gear-heads with all aspects of ATV ownership, from maintenance, repair to troubleshooting.

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