You two-stroke riders think you’re so cool. Belching smoke everywhere, yelling BRAAAP at random people, telling your relatives at Christmas that you just love being on the pipe. I’m not here to question your judgement, but you’d be even cooler if you had a street legal two-stroke dirt bike to run the streets on.
There are infinite reasons why riding a dirt bike on public roads is the most fun you’ll have with your clothes on. And if you know dirt bikes or vintage road bikes, it’s safe to say you’ve heard stories about two-strokes and how wild they are. But there are some questions. If you were to build a street legal two-stroke dirt bike, would it be any different to live with than a four-stroke? And the biggest question of all…
Should You Make a Two-Stroke Street Legal?
Feast your eyes on The Power of Sound, the greatest ode to two-stroke dirt bikes ever produced. Featuring the venerated KTM 300EXC two-stroke dirt bike, after seeing everything that bike can do it’s no wonder people want to ride them legally on the streets.
If you’ve read our other article on two-strokes you know how a two-stroke engine works, why two-stroke dirt bikes are so punchy and lively, what being “on the pipe” is, and the unfortunate reasons why street legal two-strokes aren’t more common than they are today. You also know that two-stroke engines have better power-to-weight ratios, around 30% higher than those of equivalent displacement four-strokes. And if you haven’t read it yet, now’s your chance.
So how does all that extra power reach the road?
Two Stroke vs. Four Stroke: What’s the Difference?
A two stroke is a totally different animal in several areas.
Starting and idling
For starters, you wouldn’t let a street legal two-stroke warm up in the morning the way you would a four-stroke. Excessive idling leads to a buildup of oil in the exhaust system, and that built-up oil acts like a magnet for all the small particles leftover from the combustion cycle. Before long the exhaust system gets gunked up, which is why you don’t see people letting their two-stroke dirt bikes idle for long even after a cold start.
Instead, you’ll want to start riding immediately – just go easy for a bit. Stay off the pipe for a few minutes by keeping your throttle inputs smooth and your revs low.
Oh, and remember to be deliberate if you’re kick-starting a high displacement two-stroke dirt bike. People have broken ankles over less.
On a smaller displacement two-stroke, basically a 125 or less, you’re not going to have any engine braking to speak of. The difference from a four-stroke is like going from a Honda CBR to a Ducati Streetfighter, with even more immense torque if you step up to the bigger two-strokes. In short, you’ll use your brakes more often than you may be used to. No big deal.
Two-stroke dirt bikes don’t have the linear power curve you’re familiar with on your ZX6R and in your Honda Civic. Actually, VTEC might be a good comparison for what these bikes will do at the right RPMs. In that sense a two-stroke is like VTEC on steroids.
If you don’t keep two-strokes in their power band they fall flat on their face. To stay on the pipe, you’ll have to shift a smaller two-stroke more than an equivalent displacement four-stroke. But if you’re riding a larger street legal two-stroke on the road, you won’t shift as often as you would on the trails or in the woods. It’s all in the CCs.
Once you learn the bike’s power curve you’ll know how to unleash the power exactly when you want it – and not when you don’t. On that note…
Even experienced riders with years in the saddle can end up on the ground at the mercy of a big two-stroke dirt bike.
You don’t want your first two-stroke experience to be astride a heaving 400cc or 500cc monster. Starting on a 125 or smaller helps you get familiar with being on the pipe and how instant that torque can be. Deploy that power at the wrong moment and you’ll send your ass straight to the concrete, ass-first.
As with any motorcycle, riding a smaller bike first will you learn to maintain momentum and rely less on raw power to make the bike respond how you want.
How a Street Legal Two-Stroke Handles on the Road
You essentially have a super light, super powerful, highly capable off-road machine with an unforgiving power band that you’re now trying to harness on public roads. Sounds fun right?
There’s a reason you hear old dudes raving about the street legal two-stroke road bikes of the 1970s and how “kids these days don’t understand what speed really is. They need to ride a two-stroke!”
I used to think they were delusional, or maybe they just hadn’t ridden a modern bike in a few decades. Throw a leg over one of these smoke-belchers and you’ll see how wrong I was. Two-strokes are every bit as crazy as they say, which makes getting them right extremely rewarding.
Making a Two-Stroke Dirt Bike Street Legal
If you think you’re up for the challenge, all you need is a two-stroke dirt bike and a few hours’ time.
For starters your bike will need a headlight, tail light, blinkers, horn, license plate light, and anything else required by your state’s laws. We sell most of those accessories in our store, and almost any two-stroke dirt bike can be converted for street legal use in just a few hours. You might also find some sticky tires to help keep all that power in check – and hey, why not some supermoto wheels like the Warp9s we carry?
The most important things you need are a license plate, registration, and title. But what if your bike only came with a bill of sale or an MSO? What if there was never a road-going version of your dirt bike?
Dirt Legal will get you a title and tag to make your two-stroke legal in all 50 states. The whole process takes only a few weeks and costs less than $400. We’ll get you a clean and legal title and you won’t have to visit the DMV, fill out miles of nasty paperwork, or even have your bike inspected. It’s a win-win.