I put it all together using whatever parts I had on hand. A rare Dax with a knob-head engine! [Portrait of a 4MINI Enthusiast]

The term “enthusiast” can take many different forms, from those who are completely eccentric, to those who have an insane collecting habit, to those who customize their beloved cars themselves. Such enthusiasts are respectfully referred to as “perverts,” and 4MINI enthusiast Katsumi Nagasawa, introduced next, is certainly worthy of the title. He has been fond of motorcycles since high school, and after branching out into four-wheeled vehicles, he spent his 20s, 30s, and 40s customizing old trucks and other vehicles. When a Honda Ape purchased for his son became obsolete, Nagasawa, the father, inherited it and discovered the joys of minibikes.

However, since it is a moped, there is a limit to how much performance can be improved. So he started tuning the engine, which led him down the path to customization. Nagasawa is self-employed, undertaking exterior wall and foundation work on buildings, and has relatively free time. He has been buying parts with his pocket money and customizing the Ape in his spare time. As mentioned in a previous article, the only original parts remaining on the Ape are the frame and fuel tank, and the engine, transmission, suspension, exterior, etc. have been thoroughly customized.

When he takes his customized Ape to events such as meetings, he often meets like-minded people. Meeting people who also do DIY customizations has further broadened the scope of his 4MINI customizations. The reason he decided to interview Nagasawa in the first place is because he met him at the Monkey Meeting held in the spring of 2025. Apparently he attends every year without fail, and it’s no fun to have the same machine every time. So he has decided to customize not only Apes but also many other bikes.

Of course, Nagasawa also tried his hand at the 50cc era Monkey, a symbol of the 4MINI’s popularity. However, he was not satisfied with the results, and several of them were left unfinished. Because they are popular cars, simply customizing them in the usual way would mean that they would be the same as someone else’s. It seems that as he searched for his own unique method, work inevitably came to a halt.

He has done similar work on nearly 20 machines so far, so he has purchased a wide variety of customization and tuning parts. However, since he is working with his pocket money, many of the parts are second-hand. Of course, he does not use the parts he obtains as they are, but disassembles them first and finishes them to a state that he is satisfied with.

This is the height of perversion. Nagasawa’s garage, which we introduced in the first issue, is what he himself named “Nagasawa Cycle Industry,” and to the unfamiliar, it would look like a motorcycle shop. The 20 machines he has is impressive enough, but what makes it even more bizarre is the sheer number of parts he has. Frames, mufflers, and exteriors are lined up on the walls, and disassembled cylinders, heads, and other parts of many machines are lying around on homemade shelves. With just these parts, you’d think that almost any customization and tuning could be done.

If you look at it from the outside, you’d think so too, said Nagasawa, the man behind it. He set out to customize a Dax that only had a frame, using a collection of parts. This is the machine we’re introducing today, and the engine, which has been made into 88cc with Kitaco pistons and cylinders, is based on a rare old engine called a “cob head.” The reinforced clutch and cross transmission are made by Takegawa Special Parts, and the muffler is also made by Takegawa Special Parts from that time. A full range of customizations have been made, including lowering the bike and changing the front brake to a disc.

So far we’ve introduced three of Nagasawa’s favorite custom machines, but there is one that he will never forget. It’s a Honda CBX400F that a friend bought new when he was in high school, and then inherited a year later. In fact, the reason he decided to build a garage was because he had too many bikes, but the CBX400F is the only one that he doesn’t keep in the garage. It’s actually stored in his newly built parent’s house. When the house was built, a dirt floor was added near the back door, and the boundary with the living room was separated by a row of arowana tanks. It is here that Nagasawa keeps his CBX. This shows just how attached Nagasawa is to it.

The CBX400F has been with essentially two owners for over 40 years. It was Nagasawa’s favorite machine for a while after he acquired it, and it was equipped with Tomaselli clip-on handlebars, a Yoshimura muffler, and a BEET under-cowl and tandem bar, just like in those days. He has maintained it in that condition for over 40 years, and even after his passion for the 4MINI grew, he has kept it in that condition. He has not made any further customizations, probably because it is a companion from his youth.

Although he has fewer opportunities to ride the CBX400F than the 4MINI, on the day of the interview the CBX400F was in such good condition that the engine started up on the first try. The CBX400F will probably be stored at Nagasawa’s house until the day comes when he can finally put down his bike.

Owning over 20 vehicles! What is the moped customization mania that started with the Ape seven years ago? [Portrait of a 4MINI Maniac] | Motor-Fan [Motor Fan] A media platform that distributes mainly automotive-related articles

As previously mentioned, the 17th Monkey Meeting, held in May 2025 at the Tokyo Summerland parking lot, was a huge success, attracting over 550 vehicles. I have covered this event many times in the past, and as the name suggests, it was truly a […]

https://motor-fan.jp/article/1298611/

Only the frame and tank are genuine! A modified Ape finished with used parts [Portrait of a 4MINI Enthusiast] | Motor-Fan [Motor Fan] A media platform that distributes automotive-related articles

In a previous article, we introduced Katsumi Nagasawa, who enjoys customizing only mopeds, also known as 4MINIs. He has been steadily customizing his bikes in the garage he built behind his house, and now has a collection of 20 bikes. He’s always loved motorcycles […]

https://motor-fan.jp/article/1302763/