How to -

Use a Pressure Washer

We've all seen the stories and words of worldly advice, "never let one near your bike!,pressure washers ruin bikes!, it'll strip the grease from bearings!," 
Errr right. That'll be why virtually every valeter in the country uses one, BMW use a big one in their cleaning bays and Ride Magazine did an article on which is the best to buy. Let's face it, if you let a monkey lose with a machine gun someones gonna get hurt, and if you go mad with a pressure washer somethings gonna get damaged. Fact is pressure washers are powertools, they're one of the quickest and easiest ways to clean and rinse your bike, they're also somewhat more environmentally friendly than a hose by using less water to do the job. Bit like having a shower instead of a bath, (something to think about if you're on a water meter eh!) Like all powertools there's a right way and a wrong way to use them.
Zone 1 - Aggressive - don't use this area anywhere near the bike. This is for patios
Zone 2 - Brush like - enough pressure to replicate the action of a reasonably stiff brush
Zone 3 - Washing & Rinsing - low pressure area good for getting water onto the bike
Zone 4 - Misting - Hardly worth describing this area, it's about the equivilant to heavy sweating.
                           Good for 'misting' over to keep shampoo and stuff from drying out though
So, what's right and what's wrong. Like most in our business we use a pressure washer and for a number of good reasons.
It's quicker and easier than lugging heavy buckets of water around
It's versatile, by varying the distance of the lance we can use it to wash and rinse, mist over and remove dirt like a brush
It's far more economical and evironmentally friendly than a hose
In fact while your average hose delivers around 3,500ltrs per hour, the average pressure washer delivers about 400lts per hour. The industry reckon on a pressure washer using up to 80% less of a valuable resource - water.
Which model to buy
You don't need some huffing great beast of a washer to do your bike, virtually all the models available off the shop shelves will do the job for you. Whether you want wheels on it, lengthy hoses or fancy hooks to hang the cables on is down to your personal preference and the size of your wallet.
Karcher seem to be the most popular and even their baby model will do what you need. One point to note, most models now come with a couple of different lances like the one shown opposite. The one with the pyramid looking bit on the end is a pencil jet lance. It swirls the water round internally and it comes out in a fine powerful jet, these lances are for fending off attacking crocodiles and drilling holes in rock! they're way too powerful to use anywhere near your bike so bung it in the garage. The other one is the one for you, some have a twistable end to adjust the volume and fan spread (often called a Vario lance) you can play around with it but we just wind it up to full. As you'll see next it's the distance 'from' the nozzle that matters.
How to use the Lance
Now blasting the grunge of your patio is not the same as washing your bike. There's a bit of maths somewhere that allows you to work out the 'fall off' in pressure relative to the distance from the nozzle, but who the heck needs that! It's common sense, the further away the nozzle the less the pressure. This means we can use this bit of infomation to do different tasks with the lance. We've broken it down into 'zones', hopefully the little diagram below makes this clearer.
Exactly where the boundaries of these 'zones' are depends on the model and lance, best to practice on something 'other' than your bike to get an idea. As a 'rough' guide, anything closer than 6" is Zone 1 -  6" to12" would be Zone 2 - 12" to 36" would be Zone 3 and anything above that obviously Zone 4. The pressure also varies within each zone, Zone 2 for example could be the difference between a stiff brush and a soft one depending on which end of the zone your using.
It seems to come as a surprise to some owners, but your bike is designed to be waterproof. Stood out in a decent thunderstorm or belting up the motorway in heavy rain will dump a lot more water on the bike than you're going to with your new toy. There are some areas however that aren't meant to have water blown into them. They should be pretty obvious, for example guages and switches. Dousing them with Zone 3 won't do any harm (provided of course they weren't broken or damaged to start with) it'll be no different to a decent rainfall. For air intakes and exhausts don't point the lance directly into them. You can bung a cloth in or tape a bag over, you can even buy rubber bungs to go in the exhaust hole while washing, but as you get used to using the lance you'll get experienced at avoiding any problems.
Zone 2 comes into its own for shifting dirt off heavily grunged areas. It's this that gets the doom and gloom boys all in a frenzy about damaging the bike and driving gease out of bearings and forcing dirt and water past seals. Once again a little common sense and a bit of technique go a long way to ensuring that doesn't happen.
The common sense is don't use Zone 2 on the delicate bits, like gauges and switches, decals and trims or any loose fittings etc. Those are what your brushes and shampoos are for.
On the grungy areas, start just outside Zone 2 and see how it's going, move gradually closer as needed
As if you need telling, stay out of Zone 1

All in all nothing too scary then, it's down to three simple, basic things  -  Common sense  -  Distance from the nozzle  -  Angle of the Lance.
The Golden Rule is, you don't use a pressure washer to blast dirt off a bike, you use it to rinse off dirt that your shampoo and cleaners have already dealt with.

One final tip we can pass on here. Rinsing the bike after washing is very important. Any cleaning chemicals left on will dry out and could cause staining or worse leach the colour from surfaces. To finish off a good idea is to remove the lance from the handle and just use the handle to run a 'sheet' of water over the bike. Because there's very little pressure doing this you can get in close to wheels, head stocks and swingarms to thoroughly rinse them out. While you're doing it run your fingers over the surfaces, if it feels squeaky clean you're done, if still slightly slimey keep rinsing.
Looking after your Pressure Washer
There's little you can do to repair domestic pressure washers other than replace a few seals if they go, so best to prevent them going faulty in the first place. Here's a couple of bits of advice.
Hoses tend to be plastic so take care they don't get kinked or twisted
Running a pressure washer 'dry' will destroy it. Always prime the tank by running water through it before switching the power on
In freezing weather any water left in the pressure washer tank will freeze and damage it. Store it somewhere it can't freeze or wrap it up well.
The technique bit is the angle you hold the lance
Don't hold it at 90 degrees to the surface. That'll drive dirt into the surface
Do aim the lance at a low angle. That'll blow dirt and water off the surface
aaaaaaaaaaaaiii