WD-40. Everybody's favorite lubricant, squeak stopper, rust inhibitor and moisture repellent. Therefore, it's certainly every rider's go-to when it comes to dirt bike maintenance, right?
Yes it should be in your box of tools alongside the other Moto specific chemicals. Yes you'll use it. But no, don't include it as part of your regular arsenal of products that keep your bike running on the track or trails.
The WD in the name indeed stands for Water Displacement and the 40 represents the number of formulas tried before they settled on the right one in 1953. WD-40 was first used to protect the outer skin of the Atlas Missile from rust and corrosion. For more information check out the company's About page.
As far as its benefit on dirt bikes it's likely some of you, perhaps many of you, use it regularly on your dirt bike for a variety of desired results. Some folks, we've learned, practically douse their bikes in the stuff and swear by its protective properties. It's not to say it's wrong, you could very well get by using WD-40 on your dirt bike for years without much fault.
But it's not a best practice. It's similar to using 87 octane in a car that recommends 91 or above octane. You'll get it away with the lower cost gas but you'll get better mileage, performance and overall care if you pony up for the fuel that costs 20 to 30 cents more a gallon.
Using WD-40 on your chain drive is probably one of the most misunderstood applications we've heard. The miracle of WD-40 is its ability to clean and lubricate at the same time. So using it on your dirt bike's chain and sprockets seems like an obvious application. Maybe for a mountain bike.
It can in fact be used to clean your dirt bike's chain as its formula includes soil removal agents but other products do a much better job at removing gunk and dirt from a dirt bike's drive components. However, its viscosity properties as a lubricant offer little to no protection from the energy forced on the chain by the engine. It's no match against industry favorites like Chain Wax or other popular lubrications. Do not use it as a chain lubricant.
Removing a rusted screw from your fence with WD-40 is one of many uses shared down through time since the product's inception. Unless you're working on a junker, which if you are go ahead and use it, you shouldn't have a rusted bolt that needs removing on your dirt bike. However, those axle nuts or triple clamp pinch bolts you forgot to coat with anti-seize probably won't budge with any amount of WD-40 because you'll never get the amount inside to help loosen the threads. Next time use anti-seize.
WD-40 is not grease. Therefore don't use it on ball bearings. Sure it works initially, like for example on a sticky wheel bearing because of its lubrication properties, but since it also cleans, eventually you're left with little to no grease and then damaged bearings. If you use it in a pinch so you can keep riding for the day, be sure to get grease on those bearings as soon as possible when you can perform the correct maintenance.
When it comes to dirt bikes, it's best to use industry standard fluids and lubrication
Legitimate WD-40 uses on a Dirt Bike
Yes, WD-40 does offer some applications for your dirt bike. Since the formula contains petroleum distillates and disperses water it does quite well on plastic. Our experience is the traditional silicone sprays, like SC1, work better, however, if you spray down your fenders with WD-40 it helps to keep mud from sticking. Keep in mind, WD-40 tends to attract dust so leaving your dirt bike in the garage for an extended period after coating the plastic with WD-40 or riding in dusty conditions might have the opposite effect but nothing a microfiber towel can't tackle.
The stuff also helps remove and prevent stains so try it on polished chrome and aluminum or just about any metal that stains. Just take a rag dampened with WD-40 and rub down all the bare metal parts.
The bottom line on WD-40
Think of WD-40 as your last line of defense. It's a must-have in the garage and a nice-to-have in your trail kit or track tool box. Don't use it in place of the manufactured recommended fluids. But we'll tell you a little secret, if it's between not lining up at the gates or getting to race, use it. Just don't make it a habit.