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10 Things You Need To Build A Street Legal Dirt Bike

Need To Convert Your Trail Rider Into A Street Legal Dirt Bike? Here’s How!

So you want to convert your off-road thrasher into a street legal dirt bike? In this guide we’re going to tell you how to do it, why you should do it, and tell you what bikes are already street legal, just in case you’re thinking of putting in unnecessary work. Now before we get started, this is by no means a definitive list, and rules and laws have a habit of changing at the drop of a hat, so before you get serious with your tools, check in with the Department of Motor Vehicles (DMV) and the Department of Transportation (DOT) for fully up to date regulations. Consider this an outline guide that gives you an idea of whether you’d even want to convert your strictly off-road machine into a fully functional street legal dirt bike.

Why Convert Your Dirt Bike?

Street Legal Dirt Bike - Honda CRF

There are plenty of good reasons to convert your bike. The main reason riders have is purely economical – they’ve already got a great off-road motorcycle but need the practicality of a road-legal machine, but rather than spend money on buying a second bike, it might be cheaper to adapt what they’ve already got. Another good reason is the comfort factor; a rider might be happy with the riding style, performance, and easy ergonomics of a dirt bike and would prefer to stick with what they know and are already used to rather than jump on a street bike. Sometimes it’s just a darn good project to get stuck in to. But it’s not an easy feat, and before we go through the broad strokes, you might want to consider whether it’s worth your time, money, and effort first, because there are some exceptionally good street legal dirt bike models already on sale, and buying one of those might save you a headache in the long run.

What Machines Are Street Legal Dirt Bikes ALREADY?

Street Legal Dirt Bike - KTM

Before you fun headlong into converting your off-roader into a dedicated street legal dirt bike, take a look at these already legal machines first. If you can buy an already street legal bike that has been on the right side of the law since the day it was born, that’s always better. So here are some street legal dirt bike models from the world’s biggest manufacturers:

Yamaha:

  • The Yamaha XT250
  • The Yamaha WR250R
  • The Yamaha TW200

Honda:

  • The Honda CRF250L
  • The Honda XR650L
  • The Honda CRF450X

Suzuki:

  • The Suzuki DR650S
  • The Suzuki DR-Z400S
  • The Suzuki DR200S

KTM:

  • The KTM 690 Enduro R
  • The KTM Freeride 250 F
  • The KTM 350 EXC-F

Kawasaki:

  • The Kawasaki KLX250

Obviously, there are plenty of other street legal dirt bikes out there, but this is a just quick snapshot to set your search in the right direction. But if you’re still not convinced, let’s get started with that street legal dirt bike conversion…Starting with the legality issue.

Legality And Location

Street Legal Dirt Bike - Kawasaki KLR650

Different states have different opinions about what the minimum requirements are for road-going dirt bikes, and knowing what to do and where, and getting all of that important paperwork together can be a real stress. Before you even consider converting your machine, we suggest you do one of two things. First things first, do your homework. Research the “Federal Minimum Requirement” for road motorcycles, and see if you think you can conform to your local laws. That’s not all though, you’ve got to get your bike legal on paper too, so research what you have to get your tag, registration, and title. It’ll be a lot of phone calls, so be prepared.

Street Legal Dirt Bike - Suzuki

The second plan of attack is to get in touch with a specific legal service that can do all of this paper pushing for you. Naturally, it’s not a charity service and they charge for their time, but if you’re short on time of your own or can’t face the bureaucracy, these legal companies offer quick and concise, hassle-free motorcycle document services, allowing you to focus on the fun part: the physical conversion.

Street Legal Dirt Bike - Husqvarna

The U.S. government has set up what is called “The Federal Minimum Requirement” for on-road motorcycles to make it easy to see the many requirements in one list since the details of many are buried within several sections of U.S. Department of Transportation Federal Motor Vehicle Safety Standard (FMVSS) regulations. Any motorcycle, whether born in a factory or created in a workshop, must follow the guidelines below to be considered legal for operation on state and federal roadways.

Street Legal Dirt Bike - KTM E-Ride

Either way, know this: if you’re trying to do this in California, hang up your tool belt, put down the phone, and buy another motorcycle because unfortunately, it’s just not possible in California at this time.

Essential Resources

Street Legal Dirt Bike - CRF Supermoto

No matter what route you decide to take, familiarize yourself with the specifics from the Department of Motor Vehicles (DMV) and the Department of Transport (DOT). The following street legal dirt bike conversion pointers may be applicable to one state but not another, so double check everything before getting started. So without further ado, let’s look at the most important things to consider when converting your off-roader into a street legal dirt bike.

10 Essential Components For A Street Legal Dirt Bike

Street Legal Dirt Bike - Garage

#10. A Headlight

Street Legal Dirt Bike - Headlight

Every state requires that you install a DOT-compliant headlight, and even if (for some very odd reason) your zip code doesn’t require one, it should be on your list anyway because riding on the road at night without one is crazy. To make things a little more complicated than simply bolting a torch on your handlebars, the DOT requires your headlight to have a switchable high and low beam, can function in the daytime as well as at night, and come complete with an indicator light that lets the rider know which beam is currently engaged. Not so difficult really, but consider the power drain. Many street legal dirt bike conversions rely heavily on power efficient LED units to help conserve power.

Why is conserving power an issue? Well, many off-road only dirt bikes don’t come with efficient power systems, but we’ll cover that a bit later. For now, know that you’ll need a headlight with high and low beam, with an indicator for the rider, and depending on your state, it may have to be linked to a switchgear located specifically on the left hand side of the handlebar. As long as you can see it and access it quickly, you should be good, but the traditional location is what you should really be aiming for.

#09. A Functional Tail Light

Street Legal Dirt Bike - Tail Light

With lights up front, you’re going to need to add some light at the rear too. While seeing in front of you seems like it should be your number one priority, letting vehicles know where you are and what you’re planning to do is just as important. That’s why the Department of Transport insists that your rear light isn’t just a back light, but also a functioning brake light too. Other road users need to know when you’re slowing and stopping, and it just makes sense. Now, finding a tail light that you like isn’t hard, but if you can go the extra mile and find a full on tail piece that acts as a license plate holder with integrated turn signals, then you’ve struck gold, and you’ll find out why later. But before we get ahead of ourselves, here are the tail light requirements:

In some states, your tail light will need to be connected to a proper battery that can maintain a strong light for at least twenty minutes without assistance. On top of that, it needs to be able to function as a brake light for both the front and rear brakes, which is easily achieved with pressure connectors that trigger the brake light. Either way, LED units are your best friends here with regard to the battery issue.

#08. Consider Turn Signals

Street Legal Dirt Bike - LED Signals

While turn signals aren’t mandatory in some states, they’re pretty handy to have equipped. Hand signals are generally fine, but let’s not forget that we live in a time where many young drivers don’t know how to operate a clutch…or even a can opener…so while the old fashioned method is acceptable, it’s always best to avoid a potentially dangerous situation entirely by using regular turn signals. Flashing lights are always going to trump hand signals anyway, and especially at night. It makes you more visible and allows your hands to keep control of the steering instead.

The only reason not to install them is to cut corners and costs, providing your state allows it. That’s fine, but a few dollars on blinkers and a bit of time installing them is much better than getting hit up the backside because some dumb driver doesn’t understand your hand signals, right? Anyway, you need to approve DOT approved signals that have been manufacturer no earlier than January 1, 1973…depending on your area, because some states have different laws about what can be used, and how they’re installed. Once again, we advocate LEDs in this circumstance because of the power issue.

#07. Add Mirrors

Street Legal Dirt Bike - Mirrors

Mirrors are essential. We’re using the plural here, because although some states allow you to get away with only one equipped, you really want two installed. The more awareness that you have of what’s going on around you, the safer you’re likely to be on the road – it’s as simple as that. Sure, you can wing it with one, but the bigger the picture of your surroundings available to you, the easier your ride will be. So with that in mind, we recommend installing two mirrors regardless. With mirrors, it’s always worth buying a decent set that display what’s going on with clarity, and as little distortion as possible. This is a good time to avoid cheap products: not only to they offer sub-par visibility but you can guarantee the threads will suck, the chrome will flake off, and they’ll rust in a matter of seconds. True story.

Luckily, most enduro style motorcycles already come equipped with clamps that can accept mirrors. If not, the best alternative is to buy a set of universal clamps and mount them on your bars, or opt for bar-end mirrors. We don’t recommend the latter though, because dirt bike riding stances don’t really work well with bar-ends. That being said, anything is better than nothing. Putting mirrors on is probably the easiest job on the list.

#06. A Working Horn

Street Legal Dirt Bike - Horn

Horns are also odd street legal dirt bike requirements. Sure you should have one – there’s little debate about that, but there’s a kind of legal grey area that causes trouble. You see, all states require a horn, but some allow you to get away with a non-electric one, while others require a fully-electric, connected horn to pass. What we want to know is what rider is riding around with an old-school, vintage, squeeze bulb hooter? Because we want to shake their hands. To keep things legal across the board, we suggest going full electric and leaving the nostalgic squeeze horn well alone.

Luckily, horn setups are easy to procure, easy to install, and cost next to nothing. The internet is literally bursting with options, complete with install videos and easy to follow directions, and they cost as little as $10 – you could go even cheaper if you’re willing to roll the dice on an unknown brand. What’s more, these horn setups don’t demand too much power, and usually draw around 10 amps or less which is very handy when we get to the power issue that plagues some street legal dirt bike conversions.

#05. Check The Exhaust

Street Legal Dirt Bike - Exhaust

Exhausts can be a massive problem or a very insignificant one. It all depends on what your base model was and for what purpose it was built. Generally, there are three things to consider: the shape of it, the sound levels, and of course, the gas emissions. California is very strict about this, and that’s probably one of the biggest contributing factors against allowing street legal dirt bike conversions.

Some off-road exhausts are competition-use only and emit more decibels than is generally considered polite. A lot of other off-road exhausts have been bashed around to high heaven and have holes where they shouldn’t, or have broken components, which can be a huge problem. The best way to ensure that your street legal dirt bike conversion meets regulations is to buy an EPA approved exhaust and install it accordingly. Nine times out of ten, making it appear legal-looking will do the trick, and a slip on muffler generally achieves this, and should keep any sound emissions within the legal limits. You’ll want to check this one properly though, because the wrong exhaust could easily scupper your street legal plans.

#04. Street Legal Tires

Street Legal Dirt Bike - Tires

An often overlooked requirement when building a street legal dirt bike is the rubber. Every vehicle on the road in the USA is shod with tires that meet strict DOT requirements. Off-road only dirt bike rubber doesn’t need to conform to these rules, and since these dirt bikes aren’t designed for the road, their rubber isn’t strong enough to deal with highway speeds. Your tires are what keep you connected to the road, so this is something you should take seriously. It doesn’t matter if you choose knobbly tires or strictly road-use tires, they just need to have the DOT seal of approval on their sidewall. The last thing you want is for your tires to fall apart when you’re tearing along the asphalt, so don’t forget about them.

If you want to go the extra mile though, you could give your dirt bike a supermoto make-over. Essentially, a supermoto bike is a street legal dirt bike equipped with 17 inch rims and street bike tires that doesn’t compromise the dirt bike’s natural agility but actually enhances it with road bike practicality. Supermoto mod kits are pretty common and they’re definitely worth considering when you’re converting your off-roader into a street legal dirt bike.

#03. An Odometer

Street Legal Dirt Bike - Instrumentation

Only one state in the country requires you to have a fully functional speedo (Indiana) we recommend you attach some kind of instrumentation. Knowing your speed is obviously an important detail, but keeping tabs on your RPM, your mileage, engine temperature, and your fuel consumption is a pretty useful thing. Most dirt bikes don’t come equipped with enormous gas tanks, so unexpectedly running out of fuel is a possibility, especially since you won’t have ridden it at highway speeds or over long distances before and won’t be able to make a guesstimate. Aftermarket instrumentation is pretty easy to source, and fairly straightforward to install.

We mentioned that a headlight indicator visible to the rider was a mandatory requirement for street legal dirt bikes conversions, remember? Kill two birds with one stone by sourcing a dash that comes with a handy little indicator light to let you know when high beam is operating. Having it integrated into the dash isn’t essential, but it will save you rigging up some odd DIY device, and keep your bars nice and uncluttered.

#02. A Side Stand

Street Legal Dirt Bike - Side Stand

Real off-roaders don’t come with any kind of stand, center or side, and that’s because they’re a nuisance. Off-road, they can easily catch on things and cause you to crash, or in a race they’re another thing that can cause harm in the event of an accident. For off-road purposes, going without a stand makes absolute sense. But we’re building a street legal dirt bike here – and while having a stand isn’t a legal requirement at all, it’s a fairly common sense one. Despite how obvious it might appear to be, it’s one of the most commonly forgotten components during conversion.

In an ideal world, it would be awesome if we could just ride into town, hop off the bike and rest it up against the nearest wall, or lean it up against a street light. Unfortunately, that vacant stretch of wall or lonely looking street light is rarely classed as official designated parking…so you can expect the powers that be to come along and forcibly remove it. Failing that, an unofficial authority might come along and wheel it away instead. It’s not really a safety issue though, it’s just a practical one. Riding without a stand is just an annoyance you’re better off without.

#01. A License Plate Holder

Street Legal Dirt Bike - Tail Tidy

This is a pretty important thing, the ‘ol license plate. We recommend getting yourself a nice aftermarket license plate bracket or a tail tidy – ideally one that comes with an integrated rear tail light, and turn signals, but one with fixings to attach those things will do just fine. With the right product you can solve the tail light, turn signals, and license plate problem in one fell swoop. Another thing to consider is how you illuminate the plate if you don’t go for an all-inclusive arrangement, but that problem can easily be solved with an LED strip light if needs be. In fact, the whole tail tidy approach can be avoided in a pinch, providing you put the plate on display at the rear in a place where it can easily be read. Some states have different rules about placement and location, but generally, as long as it’s visible, it’s good.

But before you worry about where to mount your plate, you’ve actually got to get the whole thing declared street legal. You can’t mount a plate if you haven’t got one yet. Depending on how your local service goes, you may get the plate and will be required to mount it as soon as possible, or you may have to install your mounting bracket before being scrutinized by an inspector before they issue your documents. It all depends on your location, and how lucky you are, really. Play it safe and make the tail piece a priority, dealing with the plate, turn signals and rear light all at the same time. Once all these jobs are done, you’re pretty much good to go. But there are still a few interesting things you might want to consider.

Extra Street Legal Dirt Bike Considerations

A Proper Electrical Upgrade

Street Legal Dirt Bike - Electrical

You might have noticed that we’ve been talking about the electrics a lot. It all depends on what bike you’re converting, but since many street legal components require power you might want to consider upgrading your bike’s electrical system. It might not be necessary, but check it out just in case. Open your service manual and get familiar with the wiring, and decide whether a stator upgrade is a thing you require. You may be able to source a charging system for your model, which will make your life easier. However, if you’ve got to build from scratch, you may need a better battery, a stronger stator, and a rectifier to help convert that electricity into a usable current. If electrics are your thing, this should be a breeze…but if you’re anything like us, seek out YouTube tutorials, forum gurus, or throw money at someone else to deal with it.

Think About The Gearing

Street Legal Dirt Bike - Gearing Ratio

Off-road bikes are geared differently to road machines, and while you’re going through your street legal dirt bike conversion, you might want to pay a bit of attention to the gearing. There’s no legality involved here, you can play around with those sprockets as much as you want, but considering your bikes new purpose, new gearing ratios could really boost your on road performance. Fortunately, the internet is no stranger to gearing charts, and we’ve even covered it a little bit in the past…so give that a look.

The Final Things

Street Legal Dirt Bike - Husqvarna 2

Laws are different in every state, so there’s no real comprehensive conversion guide for building a street legal dirt bike, however, there are always odd little details that slip through the net and could give you a headache during your build. For example, your fuel tanks is supposed to be a DOT approved steel unit, but it’s hardly ever mentioned. No one really checks, but it is still the law, so don’t get tripped up by these little forgettable details.

Street Legal Dirt Bike - Supermoto

It sounds like this whole debacle is more effort than it’s worth and more complicated a task than anyone should care to take on – but the reality is that it’s quite straightforward, easy, and rewarding, providing that you follow the rules and do your homework. Get your paperwork in order, write yourself a checklist, and go shopping online for all of the right bits and bobs, and before you know it you’ll be able to bolt on what you need, stick that license plate on, and ride off into the sunset on your incredibly unique, and completely custom built, street legal dirt bike. It might look like a lot of work, and it is, but it’s totally worth it… Buying a factory made bike is great and all that, but there’s nothing quite like finishing your own project and breathing a new lease of life into an old dirt bike.

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Joe Appleton
About Joe Appleton

I’ve done a bit of work here and there in the industry – I’ve even ridden a few bikes for actual money but what it comes down to is this: I ride bikes, build bikes and occasionally crash ‘em too. I like what I like but that certainly doesn’t make my opinion any more valid than yours…

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