If you're wondering if the way you've been washing a dirt bike is the best way, or if this is your first go-round... Below, you'll find some of the best tips to consider before, during and after washing the dirt bike, as there are a few important steps to take before washing a motorcycle which will help to keep water out of places you don't want water going such as in the air intake or exhaust, as well as there are a few steps to take during the washing to get it as clean as the pro's and we'll even go over a few things to consider after the water's turned off to reduce the chances of future electrical troubles or other problems.
The tips below on how to wash a dirt bike are all tried & true techniques that work exceptionally well for getting a motorcycle clean without discoloring the aluminum, or getting water anywhere it shouldn't be, but immediately after washing the dirt bike, be sure to check out the article elsewhere on Waterproofing the Motorcycle's Electrical System as doing so will ensure long term electrical connectivity and potentially eliminate any costly electrical problems.
It is true that pressure washers force dirt and grit through the seals of the bearing(s) but with a little common sense while using a pressure washer, this can be mostly avoided, but as mentioned above, if routine dirt bike maintenance is performed on the dirt bike on a regular basis, you'll be ahead of any wear anyways and you'll have a clean & good looking dirt bike.
Hold on just a second before you fire up the power washer... There are areas you need to cover such as the intake tract and exhaust.
Once you have the air tract into the engine sealed, it's important to keep the water out of the exhaust and from ruining the packing.

What Do I Need to Wash A Dirt Bike?
You're going to need a good cleaner that will cut grease, oil and grime such as what builds up near the countershaft sprocket or under the swingarm and "Simple Green" used at full strength works wonders without discoloring the aluminum the way that some purple cleaners will, also, considering that Simple Green is a Bio Degradable and Non-Toxic commonly available concentrated cleaner that can be found just about anywhere such as home improvement stores and auto parts outlets, Simple Green just can't be beat.
In addition to the cleaner chosen, to get a sweet looking dirt bike out of this deal, you'll also need a sponge, a good scrub brush and 3M Scotch brite will come in handy for tough spots, just don't go too heavy on the scotch brite otherwise you'll have dull looking scratches in the aluminum or plastic.
Once the heavy stuff is gone, use the simple green in full concentration (or the cleaner of your choice) applied from a hand held pump sprayer, and apply it liberally all over the motorcycle, focusing on the areas you will need the cleaner to soak in such as the swingarm and linkage, crankcases in the area of the countershaft sprocket, radiator shrouds, air box area, and under the fenders.
Next, using your brushes, sponge and scotch brite, begin cleaning by scrubbing the areas of the dirt bike that have dirt remaining rinsing with water occasionally.
A few areas that are not generally thought of or addressed are:


It's very important that all the electrical connections and related components are quickly dried with compressed air to force any remaining water away from these areas, as this will help prevent corrosion or contamination of electrical connections which can cause intermittent cut outs or other problems including excessive electrical resistance which can result in the premature failure of expensive electrical components, or possibly leave you stranded on a trail, or left sitting on the gate when it drops, either of which can be embarrassing.
A great way to ensure that all the electrical connections are dry is by using compressed air in the following manner. (If you'd like to ensure that your electrical system will stand up to future washings or watercrossings, check out this article on waterproofing the motorcycle's electrical system.)
Begin with directing the air at the electrical connectors on components such as the CDI unit (black box), kill switch, ignition coil and related connectors (usually near the steering stem).

Note; Removal and re-installation of the ignition cover will likely require the use of a hand impact driver if secured with "Phillips" type screws and it's very important to be removed on bikes with a plastic cover due to a majority of these covers being distorted allowing easy water entry.
Furthermore... If you have a plastic ignition cover in place, it's highly recommended that you upgrade to a more durable aftermarket ignition cover as these will keep water out in the event of a wet track or a water crossing when riding off-road.
While the ignition cover is removed, it's a good idea to look for any visual indications of a leaking crank seal (oil residue) and check for any play in the main bearings by grabbing the flywheel with your hand and feeling for any movement in any direction. You should not feel any movement using this technique but for more details, there is an article elsewhere which details the process for checking the left side main bearing and crank seal.
Next, using compressed air, focus on displacing water from other areas such as around the throttle housing, carburetor or throttle body, pivot points, drive train and air box.
Once most of the dirt bike is dried, it's important that the cover over the intake tract, as well as the rag (If Inserted) are removed and the intake tract / boot is inspected for any dirt that may have fallen into the intake when removing the air filter or cleaning the sealing flange.
Once the intake tract is clear of any dirt or other particles, a fresh air filter should be installed and the engine should be started and ran for a few minutes so as to blow out any water that may have crept inside the engine past the air intake cover or exhaust connections.
Finally, ensure that the throttle snaps shut when released and then review the many other articles detailing techniques for performing other
Dirt Bike Maintenance to achieve a professionally maintained motorcycle.