By the mid 1970s, the Big Four Japanese motorcycle manufacturers had already seen the end looming for the two-stroke street bike. Emissions laws, noise regulations, and a new emphasis on fuel economy were ringing the death knell for the smoky beasts. The middleweight class had long been a two-stroke domain, but now the factories needed to start introducing midsize four-strokes.
The Yamaha XS400 appeared in 1977, a bored-out XS360 with an air-cooled straight twin engine that made 36 horsepower at 8000+ rpm. While it was no giant-killer, the XS was regarded as a solid all-rounder, quicker than both the KZ400 and GS400:
“A handsome, functional and economical motorcycle — easy to maintain, miserly with gas, and still competitive in a hotly contested class.” —Cycle
Our friend Nguyen Dinh Trung (@doti.ndt) of Vietnam’s DOTi Motorcycle has become something of a “Thumper King” in Southeast Asia, turning out restomod-style Yamaha singles that manage to combine classic aesthetics, vintage nostalgia, and modern performance. However, most great artists are capable of a great deal of range when necessary, and Nguyen is no exception. The evidence is this 1984 XS400 bobber he recently completed for a customer.
It’s the first twin we’ve seen from DOTi, and the first bobber-style build. Nguyen did all of the work himself, modifying the frame to accept the hand-stitched solo saddle, fabricating the sissy bar and custom exhaust, rewiring the entire bike to run off a minimalist loom with a small lithium battery, and converting the points ignition to CDI. The gas tank has hand-drawn flames, and the bike is running Progressive 412 shocks, a Harley headlight, and titanium bolts and nuts throughout.
Given the style and displacement, it’s no touring bike, but the perfect steed for fun around town:
“Bobber style, it’s suitable for riding in town, meeting friends, drinking coffee together.”
Below, we talk to Nguyen for the full details on the build.
Yamaha XS400 Bobber: Builder Interview
• What’s the make, model, and year of the bike?
YAMAHA XS400 – 1984 from Japan. This is a project for one of my customers.
• What was the design concept and what influenced the build?
Bobber style, it’s suitable for riding in town, meeting friends, drinking coffee together.
• What custom work was done to the bike?
This motorcycle’s frame has been modified to match the bobber style. Flames hand-drawn on the gas tank, the single seat, the center of gravity has been lowered, and the footrests were raised for a rebellious sitting position. All frame details were fabricated, designed, and welded by myself.
The bike had an outdated ignition system with contact breaker points, so I upgraded to a CDI ignition for more stability. The electrical system has been minimized to the fullest extent, entirely encapsulated in a small round electrical box in the middle of the frame, containing a lithium battery instead of an acid battery. As for finishing the electrical system and manufacturing CDI ignition, I have to say it took me a lot of money and time.
In addition, this vehicle is equipped with the following:
– Progressive 412 (for Harley) rear shock absorbers
– POSH CNC turn signals
– Harley-Davidson headlight
– K&N air filter
– Hand-sewn leather saddle
– Daytona speedometer
– Titanium bolts and screws
– Handmade parallel exhaust
– Handmade sissy bar
• Can you tell us what it’s like to ride this bike?
The feeling of riding it is pretty amazing. It has its own style. You feel the personality, freedom, and comfort.
• Was there anything done during this build that you are particularly proud of?
As far as I googled during my search on the net for creating a CDI ignition system, I haven’t found anyone who has done this before with this bike.
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