The smell should give it away but the telltale sign is the thin puddle on the floor right under your dirt bike.
A leaky fuel line won't end your riding day but it'll certainly delay it. It's a pretty easy fix but with some care and regular maintenance it's likely one of the last things you'll ever worry about. Other symptoms of a bad fuel line include the bike operating abnormally like it's running out of gas or "bogging out."
A bad wreck can damage the fuel line but most of the time it's one of or a combination of old age, improper storage and bad maintenance. So if you live in like, say, Arizona where it's hot and dry All. The. Time. you've got a recipe for ruining fuel lines if you don't follow proper storage methods.
Leaving your dirt bike in the sun of course is a bad deal, but even under a carport or in the shade where the dry air sucks the moisture out of rubber like a thirsty man finishing off a Super Big Gulp, it can age a fuel line prematurely causing it to shrink and crack resulting in what else, but a leak.
The other sure fire way to damage the fuel line is not adding fuel stabilizer to your tank of gas during the winter storage months. A gummed-up gas line is no better than a cracked-up gas line and you'll notice this the first time you try and start the engine because it won't.
So before you need to heed our fuel line repair instructions below use high quality fuel, add a stabilizer when in storage, and when in storage store it the correct way. For information on how to store your dirt bike, read How to Prepare Your ATV for Long-Term Storage. Yes, it's for what you guys call "couches" but the same rules apply so just read it.
Fuel line is pretty easy to reach
Now for the important part which if you're at this point in the article is really important if you're to ever ride again or at least the bike with a leaky fuel line. First thing you need to do is WEAR rubber GLOVES. Working on the fuel line means touching and sometimes getting your hands drenched in gasoline.
Steps to Repair the Dirt Bike Fuel Line
1. Turn off the petcock or clamp the line
If your bike incorporates the on/off valve called a petcock just turn it off. A fuel injection bike does not use a petcock therefore you'll need line clamping pliers to pinch the fuel line which prevents the fuel from draining out and spilling out on your garage floor and creating your own personal gas chamber once you remove one side of the fuel line. Just in case, get a bucket and...
2. Unplug Fuel Drain Screw or Plug
Some riders like to start the engine and let it idle until all remaining gas in the fuel line burns off but really the best method is to unplug the fuel drain screw or plug also called a float bowl drain plug. You can find this hanging out on the carburetor with an attached vent tube that runs between the frame and swing arm. Snake the vent tube to drain into the bucket, unplug or unscrew the plug depending on which type it is and let the remaining fuel drain into the bucket.
Nevermind the clutch work, there's your vent line
3. Remove fuel line hose clamps
The fuel line hose clamps securely attach the fuel line from the gas tank to the engine so you'll need to locate those clamps and remove them. If you're having trouble look near the petcock or fuel outlet at the tank and on the other end near the carburetor or throttle body. The fuel line is a small, usually black (but could be another color) rubber hose and attached at each end with pinch clamps or screw clamps.
If screw clamps you'll need the appropriate screwdriver, usually a Phillips head or Allen wrench (hex socket). Loosen the screws and free the clamps. In the case of pinch clamps, unless you've got some really strong hands and fingers you probably need pliers in order to un-pinch the clamp and remove the hose which at this point, whether its attached by screw clamps or pinch clamps, is probably not going to wriggle off very easily.
A third option is crimped-on hose clamps, which unfortunately provides a bit more work as you'll need to cut them off. You'll need a clamp kit. If the manufacturer of your bike really wants to make things interesting you might need a special type of tool so check the owner's manual and if it becomes too difficult, find a mechanic with the appropriate experience and tools.
4. Remove Old Fuel Line
Like we said earlier, you'll probably wonder why the clamps were ever needed with how tight the hose is but that's after years of riding and lots of heat to help meld the hose into place. Twist the fuel line and once it rotates a bit you're golden. Just work it back and forth until you set it free. Repeat this process for the other side.
5. Install New Fuel Line
Cut the new fuel line to the appropriate length unless you have a fuel injection model which is sized to fit. Work the fuel line over the inlet and outlet extensions (or nipples) similar to how you worked out the old line. Once in place, clamp the line unless you've got a fuel injection model that snaps into place and locks without the need for clamps. Don't use any grease or lubrication. Not only can it clog your fuel system but even with clamps it can come undone. Repeat the process on the opposite end. Note: Don't forget to place the clamp over the hose before you slide it on the extensions.
Petcock and fuel line are right next to each other
6. Check for Leaks
For petcock valve equipped bikes, close the float bowl drain plug and replace the vent hose then turn on the fuel. For fuel injection bikes prime the system by cranking the bike. Check both ends of the fuel hose including the connectors, fitting and the extensions the new line is attached to.
7. Go Ride
Once you verify you've correctly installed the new fuel line get out and ride. You'll know pretty quickly if you've erred in some way and readily identify where the leak is coming from so you'll have to repeat the steps above in order to safely fix the leak. More than likely, you didn't properly fit the line to the inlet or outlet extension and/or put the clamp on incorrectly.
Replacing the Fuel Filter
The same steps can be applied to replacing the fuel filter. However, most dirt bikes don't use them anymore but if yours does it should be replaced every few rides. (If you get sick of changing it, just remove it. You'll then need to replace the fuel line.) The dirt bike fuel filter is attached to the fuel line and located in the middle between each end. You'll want to clamp either side of the filter to cut off the fuel. The filter is attached to the fuel line using similar clamps noted above. Fuel injected models install the filter inside the tank - Find a mechanic.
Written By: AndrewT