This bike started as a 2015 YZ450F and turned into a garage-built electric bike.


This is a complete one-off, exclusive, unobtainable, not-for-sale, built-in-a-garage, Frankenstein-like project bike. SSE stands for “Sires Systems Engineering.” Dain Sires is the one-man show who is the owner and builder of this bike. Dain lives in Cedar Falls, Iowa, and he’s worked in a few different roles at John Deere. Now, he’s the Senior Mechanical Engineer with the battery team, working on the electrification efforts of John Deere. He’s also an avid motocross rider who grew up on two wheels and has spent time racing dirt track cars as well in the Late Model classes.

Like many gear heads, Dain likes tinkering on bikes. He owns two Yamaha YZ450Fs and a Yamaha YZ250 two-stroke. Dain’s first e-bike build was created to help him race over rocks and logs at local EnduroCross events, and that led to his second SSE electric bike, which is the bike MXA tested, a YZ450F converted into an e-bike. The bike has gone through multiple battery and motor configurations to get to where it is today. 


Dain Sires’s SSE electric bike uses a 2015 Yamaha YZ450F chassis, but because he removed the engine, fuel tank, and radiators, he had to 3D-print support braces for the shrouds, and he also printed a chain guard and motor cable cover. When asked how he made the parts, Dain said, “The process I use for making the 3D-printed pieces is as simple as it gets—make a cardboard template and write some notes and dimensions on the back—then turn it into a 3D model with CAD. I use Autodesk Fusion 360 for home projects, which can be downloaded for free. Another thing to note, I’m also making the parts with a material called “tough PLA.” It has similar toughness to ABS plastic but prints well on any cheap 3D printer.”

The display screen behind the handlebars is typically used for electric bicycles, but Dain explained that it’s easily adaptable, and he’s used it for multiple electric projects. The display shows the amp-hours and capacity of the battery, how much energy he’s used, and how many kilowatts the motor is making while he’s on the throttle (but obviously it’s hard to monitor that when you’re on a motocross track). There is a switch on the airbox cover that can switch the motor into forward, neutral and reverse. Dain explained that reverse is helpful when loading the bike (we tried riding it in reverse on flat ground but couldn’t go more than a few feet). There’s another switch on the left side of the bars to turn the regenerative braking on and off. 

The battery is sourced from a Ford Escape plug-in hybrid. The motor Dain used is built by Mod Energy, and he believes they co-developed it with Zero Motorcycles. Dain bought it directly from the factory. It’s air cooled, and it has a lot of capacity for continuous power. As for mapping, Dain can adjust the power characteristics, but he set the bike to run at full power with his right hand modulating the power. For the gearing ratio, he uses an 11-tooth countershaft and a 60-tooth rear sprocket. To accommodate the extra-large rear sprocket, Dain added a secondary rubber chain guide off a Honda four-wheeler that he found on Amazon. He also had to drop the lower chain guide down an inch. 

The biggest loads on the motor come when you’re landing off a jump at full throttle. That puts a tremendous load on the motor mounts, the shaft, and everything else. Dain actually 3D-printed parts to stick under the motor to act as a cushion. The plastic part absorbs all the shock loadings and transmit that energy into the swingarm bolt. 

We didn’t bring any of our electrician friends with us to this test, so we had to learn all about electricity from Dain without an interpreter. Dain explained that when your voltage goes up, your complexity goes up. A higher-voltage bike requires extra battery management and extra sensors on all the battery cells; all of which adds up to extra weight and takes up space. When your voltage is high and your amperage is very low, your system has a disparity of complexity. Dain’s bike is running 100 volts, and he’s able to go up to 450 amps. 

The electric motor is a direct drive to an 11-tooth countershaft sprocket. There is no transmission to help retain as much power as possible.


The topic of electrification is a polarizing subject; the off-road motorcycle world is certainly against the idea of electric bikes. Truthfully, there are some valid reasons to be concerned with electric dirt bikes making their entrance into the sport. Politicians have muddied the waters big time with their pie-in-the-sky regulations and bans, with serious implications for the off-road motorcycle industry. 

Beyond the gross political agendas, there’s a serious debate about electric bikes in motocross. There are benefits to starting kids out on electric bikes because they are easier to ride and much easier for parents to maintain. Those same e-bike benefits help adults learn how to ride motorcycles more easily as well. We used the KTM Freeride electric bike that we tested in the December 2022 issue of MXA to teach first-time riders the basics with great success. Electric bikes also open opportunities for new riding locations. Noise complaints and dust are the two biggest reasons for tracks closing, and dust can be mitigated.

Where electric bikes present a sticky wicket is in fitting into the traditional class structures of motocross and Supercross. They are not the equivalent of a 250cc four-stroke or 450cc four-stroke and probably never will be. They can be tuned to make abundant power, and that makes catching cheaters a much harder job for race promotors and officials. It is best for the time being to form electric classes, where electric bikes race against other electric bikes, to avoid the AMA travesty that gave four-strokes double the displacement of two strokes, leading to the demise of affordable 125cc and 250cc two-stroke racing. The sport needs to tread lightly down the path of integrating electric bikes into the internal combustion classes.


Hard? No. Weird? Yes! Because there’s no gearbox and no clutch, it’s a simple “twist-n-go” operation. That part simplifies the riding, but it certainly feels unusual to be on a dirt bike without the engine noise and without a shift lever or clutch lever. It was especially weird to try to hit turns and make some roost, because we couldn’t rely on the clutch to help light up the rear wheel. Absent a transmission, crank and piston, the SSE electric dirt bike has a lot fewer internal moving parts inside of the motor. On the track, the rotating mass in an engine has a big impact on the bike’s handling. When you get on the gas in a corner, it’s the momentum from all your bike’s rotating parts that stands the bike up on its two wheels. In the same way, it’s the momentum of the wheels that balances your bike out in the air. When you hit the rear brake midair, your front end drops down. Hitting the gas midair (panic rev) causes your front end to come up. And, if you accidentally hit the front brake midair, you’ll become unstable, and the front end will rise slightly. The SSE could do some of these things, but there is a re-education program that needs to be adhered to to get it right. 

The SSE YZ450E felt like a YZ450F for the first two laps on the track.


If the rider is lightweight and mellow on the throttle, the battery lasts for a while, but if he’s heavy on and off the throttle, it won’t last long. With most MXA test riders weighing over 170 pounds and riding the bike hard, we got about 18-20 minutes of full battery power. It rained a bunch in California before Dain arrived, which meant that Glen Helen (and every other public track) was flooded. In search of a place to ride, we went to a one of our fun tracks in the high desert that had some decent little hills, a few fun jumps, a little rhythm whoop section, some loamy sand corners, and some hard-packed spots.

If the track were dry and hard-packed all the way around, the bike would last longer, because you’d have to be smoother on the throttle. But, because traction was at a premium and some of the sections were soft, the MXA test crew was zapping power more quickly on the e-bike. We wanted to make the most of our day of testing this bike, so we never rode a full-length moto from full charge to empty battery, because then we would have had to wait while the battery was recharged. We rode three sessions on the SSE bike, and we had multiple one-hour charging breaks in between. Instead of riding consistent laps, I made sure to only do a few laps at a time, so our camera crew could capture different areas on the track, and we could discuss how the bike was working with Dain. 

Dain Sires sourced his battery, motor and display from different manufacturers. This display shows the amp-hours and capacity of the battery.


It was impressively quick! For the first two laps, the bike rivals 450 four-stroke power, but after two hard laps it starts to feel more like a 350, and shortly after that a 250. It is difficult to gauge just how fast the bike is without the sound and vibrations coming from the engine. It’s easy to twist the throttle aggressively and be caught off guard by how fast you’re going. It’s also unimpressive to stand by the track and watch other test riders ride it. It is especially confusing when you have to clear big jumps. Without a roaring engine, it’s hard for your mind to process how fast the bike is going. It’s like watching a flashy young Pro rider and a smooth and experienced Pro on the track at the same time. Your eyes are drawn to the flashy kid who looks and sounds faster (and is much harder on his equipment), but when the gate drops or the lap times are revealed, the smoother rider is surprisingly quick. Watching the electric bike go is similar, only it’s magnified because it’s so quiet. 

The biggest difference between an electric bike and an internal combustion engine dirt bike is the consistency of power. Dain’s YZ450E was snappy and fast for the first couple laps, but the battery’s strength slowly depleted throughout the session. 

This is the regenerative braking switch; it acted like engine braking on the track.


Prior to the 2023 Yamaha YZ450F, the words “nimble” and “YZ450F” had never been used in the same sentence—especially not with the 2015 YZ450F; however, even with the Yamaha chassis, this bike didn’t ride like a Yamaha. On any dirt bike, the handling characteristics are never the sole product of the frame and suspension—the powerplant always affects the bike’s balance. A 125 two-stroke engine, with its lightweight piston and crank, has less “rotating mass” with less inertia than a 450 four-stroke. This gives 125s a nimbler quality on the track and allows them to lean over easier into turns. 

Electric bikes have almost zero rotating mass inside the motor, and that means that they have less rotating mass nestled inside of the bike’s frame. The motor produces power, but it doesn’t produce inertia. All of the inertia is created in the front and rear wheels. This allows electric bikes to lean into corners in a different manner. 

Additionally, Dain added a regeneration mode (re-gen) into the bike, which acted like engine braking and recouped some of the kilowatts that we expended on the track whenever we let off the throttle. The re-gen was also linked to the rear brake lever; whenever you pulled in the brake, the bike regenerated more energy to extend the ride time ever so slightly. Additionally, Dain has ways to cut the power whenever the brakes are pulled in. This means that if you’re on the throttle and you drag the rear brake coming down a hill or on a straightaway, the power is cut until you let off the brake. We didn’t want any part of this, but it was interesting to learn about the capabilities of the SSE. 

The re-gen mode was preferred because it acted like engine braking. It helped load the front end coming into turns, which helped us set up for the corners because of the increased traction. With the re-gen turned off, we had to rely much more on the brakes. The bike handled more like a downhill mountain bike; the rear end skipped out over bumps, and it was difficult to turn.  

Long-time MXA test rider Dennis Stapleton came to test the bike with us, and he was a great help, because he had been a test rider on the Alta electric motocross bike project. One of his main quibbles with all e-bikes is their throttle response. Without being able to feel the engine rev up or use a clutch, it can be difficult to figure out when and how to get on the throttle coming out of turns. As with switching from a two-stroke to a four-stroke, it takes time to learn the different styles. 

Yes, Dain uses a gas-powered generator to charge his electric bike. Dain was adamant that he built this electric bike for fun, not because he hates combustion-engine bikes. In fact, he owns multiple two-strokes and four-strokes.


The worst part about this homemade e-bike was the battery life. Because it was so much fun to ride, we just wanted to keep going; however, we can’t knock Dain on the battery life because he built this bike for himself, and he doesn’t ride longer than 20 minutes at a time. Of course, he would like to have a longer battery life, because then he wouldn’t have to charge it as often, but he prefers having big power for a short time over having small power for a long time. Plus, Dain has three young kids who ride, so while his e-bike is charging, Dain either rides his YZ450F or he’s helping his daughters have fun on their bikes. 

Beyond the battery life, the second downside of the SSE electric bike (and any electric dirt bike for that matter) was the lack of engine noise. The power was snappy and fun, dare we say “electrifying,” but the RC-car-like motor noises combined with the chain slapping against the swingarm, rocks hitting the fenders, and knobbies bending with the terrain, makes for a less-than-exciting sound. All these noises make you feel like you’re riding a mountain bike or a cheap Chinese dirt bike. Yes, the rider experience is still thrilling and fun, but onlookers are perplexed by the quiet ride. It’s hard to tell when an e-bike rider is going fast, and it’s visually confusing when you see one jumping a sizable leap. You also don’t hear them coming through the pits, which can make them dangerous to pedestrians.

It’s a little crazy to see a 60-tooth rear sprocket on the rear wheel.


Overall, the bike exceeded the expectations we had coming into this test. We agreed to ride it because the project intrigued us, but we had no idea this built-in-a-barn project bike would rival the Alta in performance. Dennis has spent a lot of time on Altas, and several MXA test riders have tried them in the last year. We all agreed that Dain’s YZ450E was comparable to the Alta and at least equal if not better in the handling department (thanks to the Yamaha chassis).



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