All things get old and in the case of dirt bikes it seems as though some parts age much quicker and need replacing far more often than others.
Perhaps this explains why dirt bike owners have a stock full of extra supplies and parts. The amount of riding, the type of riding and the style of riding all affect the longevity of parts. You can expect aggressive riding on a Motocross track to wear out parts faster than a trail ride while some riders seem destined to burn through a clutch after a few hours as others replace the top end time and again.
In any case, the average rider should anticipate certain dirt bike parts to give out sooner than others outside the usual maintenance items like filters, fluids and lubrication needs. Therefore, it helps to have spare parts because often you don't know when components have reached their limit and without a back-up, your riding day ends early. So, to help keep you riding, we have put together a list of the most common parts to fail on a dirt bike based on in-house rider experience and, of course, overall sales.
Laying off the clutch helps, but even casual riders who don't spend their weekends ripping laps on a Motocross track tend to burn through the clutch pretty quickly. Thankfully, most clutch replacements consist of the drive plates and clutch plates, also known as the clutch pack. The clutch basket and hub last much longer and a clutch replacement consists of the clutch pack, pressure plate and springs.
If you had to pick one part as the work horse on a dirt bike the chain fills all requirements. The chain propels the bike, often weighing more than 300 pounds with a rider, spins round and round at a ridiculous rate, takes you from zero to full throttle in a matter of seconds and hovers just above the ground enduring a barrage of dirt, rocks and other debris.
Despite all this, chains last longer than you'd expect but still rank high in terms of those parts that fail more often than others. The chain usually goes before the sprockets but both require replacing together when the time comes.
3. Piston (Top end)
The piston is a solid block fixed to a shaft (crank) in a tube (cylinder) and combustion happens on top of the piston thrusting it downward, repeatedly. The piston captures and transfers the energy from combustion on top of the piston in the cylinder into motion at the crank shaft. What could go wrong? A lot actually, this explains why bike manufacturers suggest performing a top end after so many hours.
Sometimes the piston seizes (much thanks to all the up and down movement) resulting in...
4. Crankshaft bearings (bottom end)
The bottom end of a dirt bike engine includes the crankshaft, seals, gaskets and the one part that fails over everything else down there - the bearings. Unlike steering stem or swingarm bearings, you can't easily clean and lubricate the crankshaft bearings. Once they fail, usually by seizing, it results in a broken crank/rod. But even when performing a bottom end based on routine maintenance intervals you have to break all the seals and gaskets so a kit includes everything needed to start fresh.
...and now circling back to the seized piston - if the piston suddenly stops i.e. seizes, you can expect a broken crank too. Then you need a complete rebuild.
Take one look at the brake system and you'll wonder how it doesn't fail more often. The brakes on your dirt bike consist of rotors, pads, levers, lines, calipers and a clevis. All these must work in unison to stop a dirt bike. The pads and rotor usually go first but the other components of the brake system get peppered with rocks and debris eventually resulting in something breaking not braking.
6. Shock Linkage Bearings
A dirt bike contains a number of bearings most of which go unnoticed until they fail. Routine maintenance like cleaning and lubrication extends the life of bearings far more than most other parts except for the shock linkage bearings. These bearings sustain the constant motion of the suspension, a much bigger load than what steering stem or swingarm bearings handle, and often get muddied up with dirt and grime. Maintenance goes a long way to prevent premature failure but ultimately time catches up and places shock linkage bearings on this list.
The more you ride the quicker tires wear out. And sometimes they go flat.
8. Valves (4-strokes)
If you don't keep the valves on your 4-stroke properly adjusted they will fail. Herein lies the problem, most riders don't keep an eye on the valves whether from forgetting or just not wanting to deal with them as you have to remove some parts.
All parts eventually fail but if you notice a seemingly high rate of occurrence with a specific part or parts, especially when compared to other riders, double check surrounding components to ensure proper installation, check-in with a riding instructor for some additional training or up your maintenance schedule and see if that solves the problem. Otherwise, it might just be normal wear and tear from a well-seasoned rider (you) who knows how to shred some laps with the best of them.