Fettling a dirt bike ready for off-road fun isn't hard, but requires a dash of specialist knowledge. So here it is
Some of the best two-wheeled experiences can be had off-road, and there are likely to be plenty of decent trails on your doorstep. But there are one or two important points to remember. On the road, fuel stations are easy to find. Despite most sportsbikes still struggling to cover more than 120 miles on a tank a trail bike will manage far less before it gets thirsty for gas, so always plan your route carefully. Secondly, the AA or RAC won't want to take a van off-road to come to your rescue if you suffer a breakdown, so preparation is key.
Checking the oil, water and fluids, making sure everything is done up properly and nothing is hanging off the bike is all basic stuff, but it's even more important to make sure everything is in good order before you hit the trail.
The majority of your time off-road will be spent standing on the footrests, so it's important to set the position of the handlebars, levers and foot controls. If the bike has been set for the road the chances are the handlebars will be too far back and the clutch and front brake levers will be too high.
To get everything in the right place, put the bike on a stand or get someone to hold it upright for you, then climb on and assume a standing position. Start with the bars. Slacken the pinch bolts enough to allow movement of the bars, but not so much they flop forward or back on their own. Get back on the bike and move the bars until they feel most comfortable while standing. Nip up the pinch bolts evenly, then torque them down to the recommended setting, always starting with the two front bolts.
Move on to the levers. Again, slacken the pinch bolts on their clamps enough to move the levers up or down. If your bike has brush guards fitted, loosen their pinch bolts at the same time. Stand up on the bike and adjust both the brake and clutch levers until they are in a comfortable position. When trail riding you will almost always have at least two fingers on the clutch, so make sure you can place two fingers comfortably on the lever at all times while standing. Once you are happy adjust the brush guards and tighten all the pinch bolts. Unlike the handlebars, which should never move, the levers and brush guards should move if enough force is used. Falling off a trail bike is inevitable, and if the pinch bolts holding the brush guards and levers are too tight the levers and guards are likely to break when they hit the ground. To test they are tightened correctly, nip the pinch bolts up and give the whole assembly a firm smack from below with your hand. The lever and brush guard should move, and be pulled back into position with a sharp tug.
Check the grips. The last thing you need is for one of these to come loose, but because they are constantly dunked in muddy puddles it can happen. To help keep them in place lock-wire tightly at three points along the grip. Make sure the wires' ends are at the rear of the grip so their sharp points don't pierce the palm of your hand.
Gear lever position is equally important. There will be plenty of times you will need to stamp down through the box or hook another gear to avoid an obstacle. Motocross boots are chunkier than the average trainer, so the best way to determine the lever position is to put your boots on and stand on the bike. If the bike has been set-up for the road the lever is likely to be too low to get a motocross boot underneath. Undo and remove the pinch bolt holding the lever on, slide the lever off the shaft and move it up to where you think the lever will be most comfortable. Get back on the bike to make sure it feels spot-on before refitting the pinch bolt and tightening it.
Most modern trail bikes have an air bleed screw at the top of the forks. Long travel off-road forks can draw air in past their seals as fully-compressed sliders rebound, and this builds pressure inside the fork. It's important to periodically remove the screw to release the air, or the seals may blow.
Another cause of blown seals are the particles that make their way past the dust cover and into the fork seal. Using a small flat blade screwdriver gently lift the dust cover. Clean underneath the seal making sure it is free from any dust and dirt and refit the seal by pressing it gently into place.
Unlike the paper air filter elements used by most road bikes, the majority of off-road machines will have a foam air filter fitted. Almost all of these are washable, so replacement is rarely necessary. Regular washing and re-oiling is essential though, and must be done after every muddy or dusty ride to maintain performance and to stop the engine sucking in tiny particles of dirt.
To clean the filter, remove it from the bike (usually easy to do after removing a sidepanel or the seat) and wash it with a filter cleaner as per the cleaner's instructions. Re-oil the filter, using a specific foam filter oil.
Lubing the chain is important on any bike, but avoid using heavy, sticky lube on a trail bike. The best way to treat a trail bike chain is to clean it thoroughly with a solvent based de-greaser then coat the entire chain with a light penetrating lube such as WD-40. Use the same lube to coat every electrical connecter block, which will help waterproof the electrical system.
Most bikes will have breather tubes with bungs fitted. These fill with water, oil or fuel and need periodical draining. Release the bung to let the fluid out.
One last tip - make sure the rear wheel spindle nut is on the right-hand side of the swingarm. This will prevent it being worked loose while riding through deep ruts.
You can't predict every eventuality, but at least try to cover the obvious stuff. Always carry a basic tool kit consisting of essential tools for removing wheels, bodywork and any parts likely to become damaged such as handlebars and levers. A spark plug and spare brake and clutch levers make useful additions to the toolkit. If, after all your meticulous preparation, you still break down, make sure you're carrying a decent tie-down to use as a tow rope - attach your bike to your mate's bike footrest-to-footrest.
Great article! but........
re. no.5 spray filter oil is shite imo, as it only oils the very out side of the filter, much better to use a good quality filter oil in a container, you can submerge the filter fully, wring it out and let the solvents evaporate before use. This way the filter is sticky all the way through and much more likely to stop any crap getting through to the engine. You can also grease the forward edge of the filter for a better seal against the air box when it is fitted.
no.7 should be done on a stand with the forks fully extended, this way you will have the right ammount of air in the forks.
no.8 also a good idea to do this immediately after washing the bike to save corrosion, I drown my bike in penetrating oil after every wash to drive water from the electrics and all the nasty little crevices it wants to sit in so it can do it corroding/rusting thing.
Posted: 15/01/2008 at 01:33
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