Eventually the day comes when your dirt bike fails to start.
You'll kick and kick and kick like it's your worst enemy. You'll swear laughter emanates from the engine. Sadly, you'll drop your head and realize the game is up. It's dead.
Wait! Not so fast.
Age certainly gets the best of all things whether alive by blood or gas and neglect can definitely shorten lifespans prematurely. Like all things mechanical, options exist.
In many respects, the old dirt bike is completely subjective. It can actually be old as in years or it can simply look old. One day-long muddy ride through the woods can turn a brand new off the showroom dirt bike into cheap garage sale send-off. But spend an afternoon on an overhaul you've got the envy of the neighborhood.
Though aesthetics give your dirt bike a shine on the outside it does nothing for the inside. No amount of SC-1 turns that motor over. So when the day comes that the engine is hard to start or doesn't start, the power disappears, you've got problems shifting or the bike just doesn't run the way it used to, you'll need to make it new again.
So, we'll tackle the most common approaches to making your old dirt bike new again and it all starts with general maintenance.
1. Replace All Bearings
New bearings won't start the engine but once going your bike sure runs nice. Broken, rusted and old bearings affect everything from power performance to steering and control. This includes:
- Linkage bearings
- Swingarm bearings
- Steering head bearings
- Wheel bearings
2. Check Chain and Sprockets
You don't necessarily need to replace the chain and sprockets if neither shows much wear but an old set or one that's been sitting around unlubricated for a few years probably has seen better days. However, a worn out chain and sprocket set won't get you very far once the engine turns over and the chain is more likely to snap when under pressure. Remember, change out the chain and sprockets together. Then...
3. Lube Everything
If we said it once we've said it a thousand times - lubricate everything especially your chain and sprockets. If you ride just three times a year and notice performance issues, do a complete lubrication service. It's inexpensive and easy and just might be the root problem. Even during a long-spell of not riding keeping vital parts lubricated prevents you from having to replace the bearings, chain and sprockets, thus saving money. Grease is cheap!
4. Check Valves (4-stroke only)
Loose or tight valves affect the bike's ability to start and run properly. The valve check isn't a common everyday pre-ride check so it can easily slip your mind and overtime the valves come loose or get too tight and you now you've got problems. If it's been a few years or you've taken on a restoration project it's probably worth your while to change out the valves anyway.
5. Replace Reeds (2-stroke only)
Reeds control the fuel-air mixture into the cylinder on 2-stroke dirt bikes and reeds eventually fray. This allows either more air or more fuel then needed which disrupts the performance and operation of the bike. In short, bad reeds make your bike feel old and frail.
6. Rebuild Carburetor
Similar to the reeds on a 2-stroke, the carburetor also controls the fuel-air mixture. If your old bike hesitates, surges or has idling problems it's probably time to rebuild the carburetor. Adjusting the carburetor to prevent operating too rich (excess fuel) or too lean (lack of fuel) works until the parts wear out.
Keep in mind, if you're using low-end fuel like ethanol-based gas from the local fill-up station the carburetor is on borrowed time. Ethanol draws in moisture which corrodes the parts and any gas left in the fuel system too long gels without fuel stabilizer and clogs the jets in the carb.
When all else fails redo the top end of your dirt bike. This replaces the pistons, rings and gaskets. In fact, even on a properly functioning dirt bike the top end should be replaced every five years or so regardless of how often you ride.
8. Replace Clutch Components
Once riding you'll know quickly if the gears slip or the clutch engages at the very end as the lever is released. It's pretty easy to see if the clutch pack and pressure plates need changing. Just check the bike's owner's manual for the specifications and how to measure the wear limits.
If you're lucky, much of the above issues with the fuel and clutch problems might be addressed by frayed throttle and clutch cables. It's cheaper, easier and a much less time consuming fix then a rebuild. Cables fray or stretch out from excessive use as well as lack of use because it usually means lubrication was not regularly applied during storage.
A common annoyance with old dirt bikes is they ride like a hunk of junk. The engine might turn over with a kick and then purr like a kitten but one lap is all your body can take. The suspension is greatly affected by the fork oil, bushings and seals. Leaky forks or even forks without any oil wreak havoc on the suspension no matter how much you fiddle with the clickers.
Lastly, change the oil. This isn't going to solve the problems of a no-start or really address any issues related to performance but if you're starting a bike for the first time in years or tinkering with an older bike you regularly ride that's lost its get-up-and-go it's always a good idea to run fresh oil as you troubleshoot your way to victory.
Written By: AndrewT