If you've been riding your bike for more than a week, you've probably realized that a new honda monkey intake is one of the first mods most owners tackle. It's almost a rite of passage in the mini-moto world. The stock airbox that comes from the factory is, to put it politely, a bit of a literal chokehold on that 125cc engine. It's designed to meet strict noise and emission regulations, which is fine for commuting quietly, but it doesn't exactly scream "fun."
When you swap out that bulky plastic box for a high-performance honda monkey intake, you're basically letting the engine finally catch its breath. It's not just about the raw horsepower—though you do get a little bump there—it's more about how the bike feels when you twist the throttle.
Why the Stock Intake Is Holding You Back
If you ever take a look inside the factory airbox, it's a maze of plastic baffles and a tiny little hole where the air is supposed to enter. Honda builds these things to be incredibly quiet and to work in any environment, from a dusty farm to a humid city. But for those of us who want a bit more "oomph" out of our Monkeys, that restriction is the enemy.
The stock honda monkey intake system creates a lot of turbulence. By the time the air actually reaches the throttle body, it's lost a lot of its velocity. When you switch to an aftermarket intake, you're usually looking at a much more direct path. A smoother, straighter tube means the air moves faster and stays cooler, which is exactly what a small air-cooled engine needs to perform its best.
The Different Types of Intakes Available
There are a few different ways you can go when you decide to upgrade. You've got the "short ram" style, the "cold air" style, and then the simple high-flow filter replacements.
Short Ram vs. Cold Air
A short ram intake is usually a short, curved tube that puts the filter right near the engine. These are great because they're easy to install and they look cool tucked under the frame. On the other hand, some people prefer a longer tube that places the filter further forward, away from the heat of the cylinder head. Honestly, on a bike this small, the performance difference between the two is pretty negligible, so a lot of it comes down to which look you prefer.
High-Flow Drop-in Filters
If you aren't ready to delete the entire airbox yet—maybe you live in a really rainy area and you're worried about water—you can just swap the paper filter for a high-flow foam or pleated cotton one. It's a subtle change, and while you won't get that aggressive "intake growl," it still helps the bike breathe a little easier than the stock setup.
The Sound Factor
We can't talk about a honda monkey intake upgrade without talking about the sound. The stock Monkey is almost sewing-machine quiet. Once you put an open intake on it, you get this deep, throaty induction roar every time you crack the throttle open.
It's one of those things that makes the bike feel faster even if you're only going 35 mph. It gives the Monkey a bit of personality. You'll hear the air being sucked in, and it adds a mechanical, raw feel to the riding experience that the stock bike just lacks. If you've already got an aftermarket exhaust, the intake is the missing piece of the puzzle that completes the "soundtrack" of your bike.
Popular Brands to Look For
There are a few names that keep popping up in the Monkey community for a reason. Chimera is probably the most common one you'll see. Their honda monkey intake kits are straightforward, look great, and they've been tested a million times by riders all over the world. They usually come with a nice silicone coupler and a K&N-style filter.
Then you have brands like MNNTHBX (man-in-the-box) or even high-end Japanese brands like Takegawa and Kitaco. These Japanese parts are often works of art—CNC machined bits and perfect fitment—but they usually carry a higher price tag. If you're building a show bike, they're worth the investment. If you just want to go faster on your way to get coffee, the more affordable options work just as well.
Dealing with the Sensor (IAT)
One thing that trips up a lot of people when they install a new honda monkey intake is the Intake Air Temperature (IAT) sensor. On the stock airbox, this sensor is tucked away inside. When you move to an aftermarket tube, you have to find a place for it.
Most good intake kits will have a specific hole or a mounting bracket for this sensor. It's super important to make sure it's installed correctly and doesn't have any air leaks around it. If the sensor is just dangling in the breeze or isn't plugged in right, your bike's ECU (the brain) is going to get very confused about how much fuel to spray, and your bike will run like crap.
Do You Need to Tune the ECU?
This is the big question. If you just change the honda monkey intake and leave everything else stock, the bike's computer can usually "learn" enough to keep things running safely. However, it won't be running optimally.
These bikes run a bit lean from the factory to pass emissions. When you add more air into the mix with a better intake, you're making it even leaner. If you also have an aftermarket exhaust, you really should look into a fuel controller or an ECU flash. Companies like DHM (David Hudson Motorsports) or CJR (Cameron Jones Racing) offer ECU flashes that are specifically mapped for a better intake and exhaust. It makes a world of difference in how smooth the bike pulls through the rev range.
Installation Isn't as Hard as It Looks
Don't be intimidated by the idea of tearing into your bike. Replacing the honda monkey intake is a job you can do in your driveway with basic hand tools. The hardest part is usually just wiggling the stock airbox out of the frame. Honda really wedged that thing in there!
You'll need to remove the seat and probably some of the side fairings to get clear access. Once the old box is out, the new intake usually just clamps onto the throttle body. Just make sure everything is tight and that you don't have any clearance issues with the frame or your legs while riding.
Maintenance Tips
Once you've got your shiny new intake installed, you can't just forget about it. Because most of these use "open" filters (meaning they aren't hidden inside a box), they get dirty a lot faster.
If you're riding in a lot of dust or rain, you'll want to check the filter every few hundred miles. Most are washable, so you just clean them, let them dry, and apply a little bit of filter oil. Also, keep an eye on the clamps. Vibration is a real thing on a single-cylinder bike like the Monkey, and you don't want your honda monkey intake falling off while you're mid-wheelie.
Is It Worth It?
At the end of the day, is a honda monkey intake worth the money and the hour of greasy hands? Absolutely. It's one of those rare mods where you can actually feel, hear, and see the difference immediately. It cleans up the look of the engine bay, makes the bike sound like a real motorcycle, and gives you that tiny bit of extra throttle response that makes zip-zagging through traffic so much more fun.
Just remember that once you start modding, it's hard to stop. The intake usually leads to the exhaust, which leads to the ECU, which leads to a big bore kit but hey, that's all part of the fun of owning a Monkey, right? It's a blank canvas, and the intake is the perfect first stroke of the brush.