Motorcycle Left In Rain And Won’t Start? Here’s Why


Motorcycles are designed to be decently weather resistant. This is especially true with modern bikes that have electronics onboard which are very sensitive to weather. However, despite the many provisions designed to defend against weather, components are always prone to wear and tear. 

So was your motorcycle left in the rain and now won’t start? Why? The probable reason your motorcycle won’t start after being left in the rain is due to water getting into your carburetors causing watered down gas that can’t be ignited. Water can also cause short circuits when it gets into essential electrical components such as the ignition system.

Rain and other forms of precipitation can cause some unexpected issues aside from a wet seat. Prolonged exposure to the elements can create even more issues. This article will go over what to do in these circumstances to clean up and repair the damage. Also, it will cover how to prevent damage from the weather if a garage is unavailable.

Why A Motorcycle May Not Start After Sitting In The Rain

If you left your motorcycle out and it got rained on and now it doesn’t start, you may be at a loss for what could be wrong. The issue is probably carb or electrical-related as water affects these components the most.

The first thing you should look at when trying to start your motorcycle after a rain storm is if any water got into your carburetors. This is more likely to happen if you have pod filters instead of an air box.

If water gets inside of the carbs, it interrupts the air-fuel mixture and mixes in with the gas. Watered down gas is unable to ignite and get the motorcycle started. The best way to combat this is cleaning out the bowl at the bottom of the carbs and cleaning your air filter. That should get most of the problematic water out of the system.

If you know water hasn’t gotten into the carbs or your motorcycle still won’t start, another likely culprit for why your bike won’t start after a rainstorm is water in the ignition system. Two places that will cause issues are the coils and/or the switch. If water has gotten in the pickup coils or magneto, corrosion will cause the windings of the coil to short. This will cause a no-spark condition and will make it very difficult to get the motorcycle running. If a coil is shorted for any reason, it should be replaced.

The ignition switch has small electrical contacts that signal the off, run, and start positions as well as the accessory position if equipped. If the ignition switch is acting up, it will likely be impossible to start the bike as the ignition circuit will be interrupted. 

While these issues may not be common, it is important to understand the potential problem. Keep your motorcycle dry as much as possible and catch issues early before they leave you stranded. Keep some WD-40 handy to spray problem areas. 

Is It Bad To Let A Motorcycle Get Wet?

Aside from being uncomfortable to sit on, letting your bike get rained on or otherwise wet will not have a dramatic effect on its condition. However, prolonged exposure to rain and weather, generally speaking, will allow some damage to occur. 

A common issue with excessive moisture is oxidation, otherwise known as rust. Most metals used in motorcycles are reactive to oxygen, but the metal is usually covered or treated to resist this reaction. Examples are chrome, paint, lubrication, and so on. Treating the metal works well to protect it, but it is prone to scratches or chipping. When this happens, the metal underneath is exposed to oxygen.

If left untreated, the oxidation will start from the chip or scratch and extend underneath the paint or chrome. This is sometimes referred to as blistering or rust cancer. Depending on the extent of the rust spot, it can take some serious repair work to correct. 

Some components that are prone to damage are wheel rims, frame, exhaust tips, shocks and springs, fenders, handlebars, and so on. Generally speaking, the components that are close to the ground are at the most risk of damage. However, these will typically be built stronger to last longer.

Another component subject to rust is the chain. Since the chain sees a lot of movement, it’s difficult to keep the bare metal-covered. The friction of the links against each other and the friction of the sprockets against the chain wear away any treatment. The chain is also close to the ground where water and road grime splash up against it. It’s not uncommon for a chain to have rust on it even when taken care of.

Noting all the damage that can occur from oxidation, it is important to remember that bike manufacturers design bikes to be weather-resistant. The paint job is usually durable and other metals won’t easily rust. The danger is prolonged exposure and inadequate protection.

Oxidation can also impact the inside of a motorcycle’s mechanics. If water gets in through the carburetor and is sucked into the engine, the oil becomes watered down and less effective, leaving your motorcycle at risk for improper lubrication. Along with that, rust can occur and compromise the stability of those parts.

Another threat that rain poses is to any electronics on your motorcycle. This can include any electronic gauges or displays, like a speedometer, as well as speakers or other electronics. Water damages these components by causing oxidation on the tiny electrical connectors and circuits. Since these use such small amounts of electricity, any oxidation creates excessive resistance in the circuit. These can often be expensive repairs to make. 

Related to electronic issues are electrical issues similar to the ignition system. Lights are sensitive to corrosion as well, which usually causes excessive resistance and burned lights or popped fuses. See our other article here to learn more about what can happen when a motorcycle gets wet.

How To Clean Up A Motorcycle After A Rainstorm

If your motorcycle was left out during a rainstorm, it is likely drenched. However, drying it off can be fairly simple. Letting it air dry isn’t bad, but if you are concerned about taking good care of it, there are other methods.

Air drying leaves the possibility of watermarks. These are caused by water leaving minerals on surfaces as the water evaporates. This won’t cause damage, but it does look bad and can be avoided by using other methods of drying.

The first way to dry your bike is simply using towels. This can be effective after a mild rain. Simply take some dry towels that you don’t mind getting a bit dirty and start wiping away the water. You will want to have multiple towels on hand to get all the water. 

A drawback to this method is the fact that towels aren’t 100% absorbent. Once it’s saturated, it becomes ineffective even if you wring it out. Having multiple dry towels helps, but having the extra supplies can be a bit of a hassle.

If you are looking for something more intense, using compressed air is a good way to go. The high-pressure air not only physically moves the water but also causes it to evaporate. This makes for an effective drying method.

Similar to using compressed air is using a blower. A tool like a leaf blower or something similar pushes the water off any surfaces. Any kind of high-pressure air will also get into hard-to-reach places to get water out.

However, using pressurized air requires having these said tools (a compressor or a leaf blower). It isn’t practical to purchase the equipment just to dry off rain. A frugal solution would be to borrow from neighbors as needed.

Finally, WD-40 will help with any potentially rusty sports. Fun fact: the “WD” stands for water displacement, meaning it moves water out of the way as it soaks into the material. This makes it good oxidation prevention as needed. Keep a can around and spray any spots that risk oxidation.

How To Prevent Rain Damage

The best way to prevent damage from the rain is to cover your bike when not in use. Parking your bike in a garage will provide the best protection. There it will not only stay dry but a bit warmer than the ambient temperature. This can help it start-up in the mornings. 

Another option is to park under a lean-to or carport. These are structures with a roof but few surrounding walls, meaning it is not entirely enclosed. These kinds of shelters protect against rain and some wind, depending on the number of walls, but won’t protect against temperature.

However, garages aren’t always available, leaving the motorcycle to be parked in a driveway or on the street. If you want to add some extra protection against the rain, it is a good idea to get a cover for it. Covers can be purchased online or in motorcycle gear stores. Some are designed to fit specific models while other covers are more universal. I recommend the Dowco All Weather Plus cover found here on Amazon.com.

When picking a cover, it’s worthwhile to spend a bit more on more durable and waterproof material.  Cheaper materials will tear and cause the cover to be useless. Always stow the cover somewhere that it will be protected and accessible. See our other article here to learn more about why motorcycle covers are important.

Conclusion

Motorcycles are generally rain resistant, but that doesn’t mean rainproof. Take care of your bike so that water won’t cause any corrosion on components, especially around the carburetors, ignition system, and any electronics. Get a good cover for your bike if you don’t have a garage to store it out of the weather. If your bike does get wet, dry it off with some towels or with some pressurized air to prevent corrosion.

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