How To Make A Vented Dirt Bike Fender – DIY For Free

Keeping your bike cool is important, especially if you’re racing in 100+ degree weather. If your dirt bike is overheating, a relatively inexpensive way to help prevent it is with a vented front fender. I’ve heard many people say they like the extra air-flow that their bike’s radiators get.

For a real test, you’d need to record the temperature differences with some temp strips. I don’t live down south in the raging heat, so I’ve never really needed the additional cooling. However, for the sake of YOU, I tested something that doesn’t require buying an aftermarket vented fender. I like free things, and if they work, that’s an even bigger bonus. I’m going to show you how to make a vented fender with some basic home tools.

First thing to do is lay out the design that you want (clean the dirt off the plastic). I just used a sharpie because that’s what we had laying around, and it works. Below is a picture of my layout. I took a peek at some motocross vented fenders to get an idea. I didn’t need anything fancy, so I just quickly sketched it on the bottom of my fender.

Vents Outlined

After I sketched out the design I wanted, I pulled out a cordless drill and a couple of drill bits. The first one is small for drilling out pilot holes. I just made 4 holes on the corners of each vent. See the picture below for an example.

Drilling Pilot Holes
I then use a larger drill bit to make bigger holes, making it easier to cut out the vents.
All Holes Drilled Out

The next step can be done using a variety of techniques. For me, this was a fairly quick demonstration, so I wasn’t going for a ‘professional’ look. I just used the same drill to cut/mill out the pockets. It is a little messy, and not very…. perfect. Another way you could do this is by taking an exacto-knife and heat it up with a torch so it cuts through the plastic more easily. Below is the fender after cutting the vents.

Vents Roughed Out

Yeah, that looks a little rough. So, I took a small exacto knife to clean it up a little bit. I’m no artist, so I just shaved the lines as straight and clean as possible without spending hours on it. Besides, it’s not like people are looking at it up close anyway. It looks pretty good on the bike, and I’d bet it would help with overheating problems…. If it had any.

Free Vented Dirt Bike Fender
And there you have it. I just took an old fender I had lying around and turned it into an amazingly cool and high-tech bike modification. Ok, well it may be a chunk of worn out plastic, but it beats paying almost double for an aftermarket vented front fender when you have the tools at home to do it.
-Tom Stark

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