Bonneville Speedweek 2026 Sponsored Items (EN)

An Interview with Team B.B.B., Taking on Bonneville Speed Week

Taking on the Last Frontier with a HONDA CM90

──What led you to take on this challenge with the HONDA CM90?

Mukasa (M): We race vintage bikes in the BOBL (Battle of Bottom Link) series, so it felt completely natural to attempt a land speed record with a machine that truly represents who we are, a bike with a bottom link suspension and an OHV engine.

──Your team is entering the M PBG100 class. Does the "B" stand for Bottom Link?

M: No, the "B" stands for Blower, meaning a supercharger. Last year we competed in the 50cc class, but this year we're stepping up to 100cc because we want to go faster. We also gained a fair amount of supercharger know how at Bonneville Speed Week last year and want to build on that experience.
Besides, it would not feel right to show up once, set a record, and call it a day. We have a lot of respect for the people who have dedicated years to this challenge. We'd like to keep challenging ourselves at this historic event for at least several years. This class is also relatively unexplored, so the records here feel attainable.
Top Speed Is Not an Instantaneous Number: The Deep Rules of Bonneville

──Tomoka, how are you feeling about competing on such a big stage?

Tomoka (T): Honestly, I'm just focused on doing my best ride (laughs). I'll get to ride through scenery that simply doesn't exist in Japan. My boss and Taku san have prepared the bike so meticulously that I can ride with complete confidence. As the main rider, my job is simply to give it everything I've got.

──It's basically just riding in a straight line. What kind of technique does it require?

T: People often think Bonneville Speed Week is about achieving an instantaneous top speed, but it's actually completely different. We're running the Short Course. The first mile, about 1.6 km, is the acceleration zone, and the second mile is the measured mile.
In other words, your record is based on your average speed over that measured mile.

──Wait, it's not based on peak speed?

T: No. You accelerate to top speed during the run up, and then the challenge is maintaining it, or even increasing it, through the measured mile. They do record your peak speed as a reference, but it does not count as your official record.

M: If you exceed the current record during that measured mile, your bike goes into what is called impound. You leave the bike with the inspectors, and the first thing the next morning you make a return run. Your official record becomes the average of the previous day's speed and the return run speed, after they verify certain items such as engine displacement.

T: So it takes at least two days to set a record. Early mornings are best because the air is cooler and denser, but conditions change throughout the day, which means the bike setup has to change as well. If you make a mistake on day one, you're back to square one. That's what makes Bonneville so fascinating.

The Pride of Running Without a Fairing and the Reality of Supercharging

──If you're aiming for top speed, why not add a fairing to reduce drag? People must suggest that all the time.

M: They do. But once you add a fairing, you move into an entirely different aerodynamic class. This year we're committed to running in M PBG100.
M stands for Modified frame.
P stands for Pushrod engine.
B stands for Blower, meaning supercharger.
G stands for Gasoline class.

──Then what are you doing to improve aerodynamics?

M: Since there are no corners, we're focusing on straight line stability and doing everything we can within the rules. We use a seat cowl that allows air to flow smoothly behind the rider and add a rear wheel cover similar to a moon disc. The rules do not allow a front wheel cover, so we removed the front brake and built a special hub to reduce drag as much as possible.

──Does adding a supercharger dramatically increase speed?

T: No, it's not some magical item. Last year my boss and Taku san spent a lot of time struggling with it.

Takahashi of Sakai Boring (S): It depends on how you use it, and there are compatibility issues with a four stroke single cylinder engine. At the end of the day, we're basically mounting a pump in front of the engine, so there are still many unknowns.
There are not many commercially available superchargers. The smallest ones are generally designed for kei cars, around 600cc engines. The one we're using displaces 200cc per revolution, and finding anything smaller is difficult.
Supercharging is actually an old technology that originated in aviation. The idea was simple: if the air is thin, compress it. For engine enthusiasts, it's an irresistible field.
Supercharging is actually an old technology that originated in aviation. The idea was simple: if the air is thin, compress it. For engine enthusiasts, it's an irresistible field.
Electric supercharging is not allowed under the regulations for this event. Your choices are limited to a crank driven supercharger or an exhaust driven turbocharger.
That's what makes it so fascinating, and also why so few people are doing it.
To be honest, we still do not understand it deeply enough to speak with authority. More often than not, we're humbled by it. Sometimes it feels like we have not even fully explored what naturally aspirated engines are capable of.

M: In fact, if you look at the records in our class, there are cases where naturally aspirated bikes are actually faster. We cannot rule out the possibility that small displacement engines simply are not well suited to forced induction.

Toward the Last Frontier No One Has Explored

──So, what's your goal this year?

Everyone: The current class record is 53.968 mph.

M: If I wanted to dream big, I'd say 70 mph. But I'm more cautious, so I'd say somewhere around 60 to 65 mph.

S: I think we could reach 120 km/h, just under 75 mph. If we can complete a run at 110 km/h, I'd say we did well. If we exceed 120 km/h, I'd say, "We're really doing something here."

Everyone: As a reference, there is a naturally aspirated pushrod powered Honda C200 record of 68 mph, about 110 km/h. Hitting 70 mph would be meaningful. Surpassing that record would have real significance.

──Why take on Bonneville?

M: The current record is only in the low 80 km/h range, about 54 mph. Surprisingly, very few people are running small displacement engines with superchargers. We've jokingly started calling this class "the Last Frontier."
There's still room for improvement, and that's why we're here. In other classes, the records are already so incredible that they feel completely out of reach. But here, we still feel like we have a shot.
If we managed to hit 120 km/h or even 140 km/h, people would probably say, "Come on, nobody's finding another 30 km/h from there!" (laughs)
That's what makes it fun, exploring territory where nobody has gone before.

2026.06.18, at ANIMALBOAT