One of the best things about the Honda Grom is that it’s easily customizable, and its long history means there are a lot of different parts on the market available for doing so.
In fact, I’ve found that a number of aftermarket parts can improve the Grom’s performance far beyond its already impressive 10 horsepower and 62-mph max speed.
These are the best Honda Grom performance parts and my favorite models for each.
Big Bore Kit
The Grom definitely has a powerful engine for its size, getting close to 10 horsepower. Nevertheless, there’s only so much speed you can get out of 125cc.
If you want to bump up the speed from the Grom’s 62-mph max, a great place to start is by increasing the size of the engine with a big bore kit.
Basically, these increase the size of the piston bores, thereby increasing engine displacement and power.
Some kits also modify the engine in other ways. For instance, some increase the Grom’s engine from four valves to two.
Honda Grom – 186 CC Big Bore kit
Koso Big Bore Cylinder Kit
KOSO 4 Valve Cylinder Head Kit for 14-20 Honda Grom
The biggest Grom kit on the market, this one ups your engine size by more than 50cc to 186cc. Plus, it comes with a fuel controller, saving you money and helping the supersized engine maximize power.
This is a simple but effective kit that increases the Grom's engine size from 125cc to 170cc. More than anything, it gives you a lot more torque and acceleration—and better wheelies.
Combined with the Koso 170cc cylinder kit, use this kit to double your Grom's valves. Including a forged piston, it greatly enhances the power and torque of your Grom so you can get better speed and acceleration on the road.
An aftermarket exhaust system will also improve your Grom’s performance because it improves airflow into the engine. As extra bonuses, it can also improve fuel efficiency and sound much sexier and more powerful.
Dual Low Mount Exhaust For Honda Grom
Coffman’s Full Exhaust System for Honda Grom 125
Motorcycle Slip Exhaust
Getting a double exhaust like this one really improves airflow into the engine for better combustion and, therefore, more power. And it just looks cool.
If you want to get creative with your Grom customizations, this is the exhaust for you. It has six color options to match your style.
A basic system that's easy to install, this exhaust can still increase your speed up to 5 mph. Plus, it has three different sound settings.
Like exhausts, upgrading your air intake will greatly improve airflow for your Grom.
This means the fuel combusts more efficiently, releasing more energy and giving your bike more power, torque and acceleration.
If you’re modifying your exhaust, you should definitely upgrade the intake as well for maximum performance enhancement.
CHIMERA BLACK Short Ram Air Intake
Chimera Cold Air Intake For Honda Grom
Tepeng Air Intake System Compatible
This is the same great Chimera intake product but compatible with the newest Grom 2022 and 2023 Grom models.
This intake is easy to install and fits in with little room for error. In other words, you can give your Grom a lot more zoom for a lot less work and worry on your part.
This is another simple intake system that's hassle-free but improves performance. While not quite as well constructed and durable as the Chimera intakes, it's much better for a budget buy.
Getting aftermarket suspension products with better travel than the factory parts, both of which have four inches of travel, makes riding the Honda Grom a lot more comfortable, especially if you’ve increased its torque with other upgrades.
Not only that, it also improves general performance because it makes the weight transfer more efficient during acceleration. This means it’s more responsive and just plain faster.
Honda Grom Rear Gas Shock Suspension
Ohlins HO 424 Shock Absorber
OHLINS FORK KIT
As a gas shock, this rear suspension greatly improves balance and absorbs impacts. That means you'll be a lot more comfortable, especially if you're on the heavier side.
Ohlins is a popular brand when it comes to suspension due to the high quality, durability, and smooth shock absorption that's well worth the top-shelf price.
Don't forget about your front suspension! With this fork kit, you can improve your Grom's reaction to bumps and holes and improve its response and acceleration.
In my opinion, a fuel controller is the most overlooked way to improve your motorcycle’s performance—and one of the best. While upgraded intakes and exhausts increase airflow, a fuel controller helps the fuel injectors increase the amount of fuel in the engine. The two together mean more power.
Increased airflow on its own will still give you more power, but it will do so by burning the fuel at higher temperatures, which can be bad for the engine in the long run.
Fuel controller plus exhaust and intake is the ideal combo, which is why many upgrade kits come with them.
Power Commander V
DynoJet Power Vision
Honda Grom Fuel Injection Programmer
This fuel controller is one of the best ways to complement your intake and exhaust to map your fuel injection and give you more power while keeping your engine safe and reliable.
The best thing about this fuel controller is the easy-to-use touchscreen interface that gives you maximum control over your Grom's fuel curve.
If you want to improve your Grom's power and fuel usage while on a budget, this might be the fuel controller for you.
Your Grom’s clutch might be a basic part, but it’s also a good one to upgrade to give your bike more performance.
A more responsive clutch means better acceleration since you can more accurately shift through gears as you speed up.
More importantly, stock clutches often wear out quickly and begin to slip, decreasing performance. An aftermarket clutch will be more durable and keep performance consistent over a longer period.
Koso Grom Clutch Kit
EBC Brakes Complete Clutch Kit, Black
KOSO Clutch Lifter Plate
Get Koso quality and performance at a great value. The high-friction discs reduce slipping and improve responsiveness.
Made with Kevlar, this high-quality clutch kit will keep you shifting gears smoothly year after year.
This lifter plate is an inexpensive way to improve your Grom's performance and gear shifting at high speeds.
You should upgrade your Grom’s rearset for one big reason: you can lean the bike over much farther, so you can take turns sharper and faster.
Rearset Foot Pegs Rear Set
Krace Motorcycle Rearsets
Billet Motorcycle Rearset
With an unassuming appearance, this reset is easy to install but increases the comfort and performance of your Grom.
I love this rearset because it allows you to adjust the clutch. Plus, the aluminum construction is lightweight for peak performance.
This is the ideal rearset to consider if you're getting creative with your Grom customization. There are a ton of color options to match your other mods.
Already a high-performance minibike, you can make your Grom an even faster, more powerful and better handling machine by installing aftermarket performance parts.
Specifically, consider upgrading your Grom with a new:
- Big Bore Kit
- Fuel Controller
With high-quality models of these parts, you can create a custom Grom that’s even more fun to ride.