Best XR100 Mods: Upgrades Based On YOUR Specific Needs

Looking for the best Honda XR100 upgrades to make it faster and more comfortable? Whether you’re an adult that wants to keep riding without breaking your dirt bike or you’re trying to make your XR last longer before upgrading to a bigger bike, you’re in the right place!

In this article, I’m going to show you the top 5 XR100 performance mods that will make it a better, faster, and safer dirt bike. Whether you’re on a tight budget and just want the cheapest upgrades or you want to go all out, there are multiple options for you.
Many of these modifications will also work on the Honda CRF100, which is just a newer version/name for the XR 100.

5. Frame cradle upgrade

Before you go any faster, you may want to consider bracing up your frame with a frame cradle. They can be a little costly, but if you are going to be jumping or doing any kind of racing, it is a must.

An XR100 relies on the stress of the engine and its mounts to hold it together, making it flex and eventually break. A BBR frame cradle (check price on Amazon) adds much-needed rigidity to the frame, taking the stress off the engine.

4. Suspension upgrades

Next, you’ll want to upgrade the suspension. Yes, you’re probably asking why we’re not doing any “go-faster” mods. Trust me, we’ll get there, but your bike must be able to handle the abuse before it can dish more out.

Every adult that’s ridden a stock xr100 knows the suspension is less-than-satisfying. In two words; it blows. Literally, it bottoms out just riding over bumps if you weigh anything over 140 lbs.

Cheap fork upgrade

Heavy-duty fork springs (check price on Amazon) are a cheap upgrade and can be swapped out at home with some basic shop tools. They’re claimed to be 30% stiffer than the stock springs, which is more than enough if you’re 150-180 lbs.

In fact, it may even be too stiff if you’re just trail riding. When it’s too stiff, every bump will feel sharper/harsh and you’ll get fatigued quicker.

Pro Tip: If adding both BBR springs is too stiff, then remove one and use one OEM stock fork spring. This will split the difference and only make it 15% stiffer than stock.

You can also use heavier-weight fork oil (Amazon) to increase the damping, which gives you a little more control when the forks are compressing and rebounding, as well as preventing bottoming – especially if you raise the fork oil height.

Cheap shock upgrade

A heavy-duty rear shock spring (check price on Amazon) is even less but is just as important – especially if you are going stiffer on the front forks. If you don’t have the front and rear suspension balanced, then you will have poor stability and/or traction, causing you to wash out more easily.

For less than 200 bucks you can have an xr100 that rides much better and is ready for those “go-fast” mods.

Upgraded rear shock

Want something better than just a ‘stiffer spring’? An aftermarket Vonkat Fat Boy shock (check price on Amazon) is an affordable way to get an adjustable and much better-performing rear shock.

Not only will it perform better than a stock shock due to its damping adjustment, but you can also rebuild it. That means when it gets worn out, you can get it serviced so that lasts longer instead of just throwing it away.

Fork conversion upgrade?

The stock damper rod conventional forks are difficult to modify unless you’re well experienced with how this type of fork works. A popular, yet much bigger mod, is swapping the stock forks with front forks from a Honda CR80.

It takes some custom modifications and fabrication work to get them to fit, and you also have to raise the rear end to get the bike balanced for proper handling. Supposedly, a 1982-1985 CR80 front-end is close to a bolt-on mod.

The newer rears require steering stem mods and a complete CR front-end because it has a disc brake. You’d almost be better off putting the XR100 engine in a CR80/CR85 frame with better suspension already.

3. Intake mods

Like many other things on this dirt bike, the intake is highly restricted. Honda XR’s run rich from the factory, but that can be fixed with a better air filter and jetting set up.

High-flowing air filter

The stock foam air filter works, but it’s not made for performance. Simply put, an aftermarket UNI Air Filter (Amazon) replaces the stock air filter and gives your XR100 better airflow, which is needed if you want to make more power while still keeping dirt out of the engine that will wear it out quickly.

Just remember to oil the air filter before installing it so that any dirt or debris sticks to it. If you don’t properly oil it, the dirt will get sucked past the filter and into the engine, which will cause a failure sooner than later!

Pod filter – is it worth it?

Swapping out the entire intake system for a pod-filter (check price on Amazon) would be the least restrictive and provide the most power gain, but I wouldn’t recommend it unless you’re doing supermoto with the bike. It’s out in the open, so it’s more susceptible to sucking in water and dirt.

Free/cheap airbox mods

A free mod you can do is drill several 1/2″ or 1″ holes around the airbox. This will allow more air to get in and to the engine.
If you’re worried about dirt getting through these oils, then you can use some Uni Air Filter Vents (check price on Amazon)

You can also pull off the air filter and remove the backfire screen on it. It restricts airflow, and an xr100 has very little chance of starting a fire by back-firing.
However, do so at your own risk. I’m not liable for your own actions.

Carb Swap

Another common intake mod that xr100 owners do is replace the carburetor with one from an ATC200X. That’s right, an old Honda 3-wheeler.

An XR200 carb will fit as well, but the 200X is the most because it’s a slightly bigger bore than the XR100 carb (24mm vs. 22mm) and bolts directly onto the xr100. If the throttle cable is too long, just buy one from a CR80/CR85.

The 200X carb will likely need to be taken apart for a cleaning, so you might as well re-jet while you’re there (or get a rough estimate on where to start).

Cheap stock replacement carb

Maybe you just need to replace your stock XR100 or CRF100 carb because it’s been sitting for so long and won’t start. While I don’t normally recommend cheap knock-off carbs, this one from Amazon has pretty good ratings and is an affordable way to get your Honda 100cc dirt bike running again if you already tried cleaning your original carburetor.

Jetting – the forgotten mod

A common mistake is modifying or upgrading the engine or exhaust and not changing the jetting. Not only are you missing out on more power, but it can actually damage your engine if the jetting is too lean.

By spending a little time adjusting the jet circuits, your XR100 will start easier, run smoother, make more power, and last longer. You can get started in just a few minutes with my Free guide here.

Stock Honda XR100 jetting:

• Pilot jet: 35
• Needle: Middle (3rd) clip position
• Main Jet: 98

Jetting with uncorked mods (a good starting point):

• Pilot jet: 38
• Needle: 4th clip position from top
• Main Jet: 105

2. Exhaust upgrade

Just want to make your XR 100 louder with a cheap but nice-looking muffler tip? This Billet Tip & Spark Arrestor (check price on Amazon) is an affordable way to get more noise that sounds better.

This only fits on your stock XR/CRF 80/100 muffler if it has the removable end cap/baffle. This means that it should work on all model years 2001 and newer.

More power with your sound

An FMF exhaust (check price on Motosport) is a relatively cheap and easy way to hop up your XR100. Not only does it open it up for more power, but it sounds a lot better than the choked-up stock exhaust.

However, if you ride in a noise-conscience area, you might want to consider keeping the stock exhaust on. Any aftermarket muffler or system will make your XR or CRF100 much louder, which could result in neighbors complaining.

Race exhaust that’s not FMF or PC

Don’t want the popular FMF or Pro Circuit pipe that everyone else puts on their XR100 or CRF100? You can get a Big Gun Evo Mini exhaust (check price on Amazon) that gives you a little more power potential.

The only downfall is that it’s pretty loud, so I don’t suggest installing it if you’re riding in an area that might get noise complaints from neighbors.

Do you need to re-jet the carb with an exhaust?

You may not need to re-jet the carburetor with just an exhaust, but it depends on your climate and current jetting specs.
In most cases, your XR100 will need some jet tuning, especially if it still has the stock jet sizes and if you’ve done the previous intake mods to make it run smoothly and get the most power out of the modifications.

1. Engine upgrades

One of the easiest ways to get more torque and horsepower from your XR100 is to give it a bigger engine. By adding a 120cc big bore kit (check price on Amazon), you’ll be able to accelerate faster to get up hills quicker or pop the front wheel up to wheelie over logs with less effort.

A big bore kit simply replaces the stock piston and cylinder. It comes with everything you need to rebuild the top-end, so if you need to rebuild the stock engine because it’s smoking or worn out, this is a no-brainer deal.

Is a big bore kit reliable?

This really depends on the parts, how they’re installed, and how well you maintain your dirt bike. A big bore kit can actually be more reliable than stock because you don’t have to rev the engine as high to get the same acceleration.
Think about it – the less RPM, the less wear and tear on the engine.

Common mistakes that make a big bore unreliable:

• Using poor quality (cheap) parts
• Not properly installing or inspecting the parts beforehand
• Warming up the engine too quickly
• Not doing proper engine maintenance

Hotter camshaft

The stock camshaft is very tame, which is fine for the stock engine. But if you upgraded to a big bore kit and better-flowing exhaust, then the stock cam is going to be restricting power – not giving you the compete performance that you hoped for.

Using a Hot Cams Stage 1 camshaft (check price on Amazon) is a pretty affordable way to get noticeable more torque and horsepower throughout the RPM range. If you’re planning on rebuilding the top end, an aftermarket cam is just as easy to install as the OEM camshaft.

How to get the most power out of your XR100

Before you do any of the last three mods, though, you should know that in order to get the most out of the bike, modifications should be done to all of them.

In other words, you’ll gain a lot more horsepower if you open up the intake AND get an aftermarket exhaust, instead of just doing one or the other.

You can get the cylinder head ported, shaved, and/or blueprinted if you’re looking to keep stock displacement. If you want to go all out, there are “Super Head” kits that come with a complete top-end, including a larger cylinder head with bigger ports and valves to increase airflow.

For this kind of money you could buy another dirt bike, but, if you’re racing it in a highly competitive class and have a lot of extra cash, I’m definitely not going to stop you.

It’s not a race bike, but…

In the end, it’s going to take either a lot of money or time (or both) to make an XR100 competitive on the motocross track. But that’s not what an XR100 is intended for; it’s a fun, backyard, play-bike.

If you have the mechanical abilities and motivation, check out my budget xr100/rm80 conversion build for some ideas on how to build the ultimate pit bike for adults…

The best mods to ride faster & safer on the trails

You can have the baddest XR100 in the state, but a good rider on a stock XR100 will beat you every time in the woods. Want to learn how to ride faster with better control? Click here to get started in just a few minutes with proper riding technique.