High-Spec Thumper: Yamaha SR400 by DOTi

Yamaha SR400 Custom

Vietnam’s DOTi Motorcycle builds one of the hottest SR’s we’ve ever seen…

Introduced in 1978, Yamaha SR400 was, essentially, a street version of the legendary Yamaha XT500 — the air-cooled four-stroke thumper that won the first two Paris-Dakar Rallies and established a reputation for one of the world’s toughest adventure machines. Yamaha created two versions of the SR, a 500cc version for export and a shorter stroke 400cc version for the Japanese Domestic Market (JDM), built to comply with the country’s licensing regulations.

Yamaha SR400 Custom

Both SR’s were intended as Japanese replacements for the British singles of yesteryear, featuring simple SOHC single-cylinder dry-sump engines with the oil stored in the frame down-tubes. You might guess that everyone would prefer the larger displacement SR500, but the short-stroke 400 soon gained its own legion of fans:

“With a compression ratio of 9:1 the shorter stroke SR400 quickly acquired a reputation for its free revving abilities and responsive power.” —Silodrome

Yamaha SR400 Custom

The SR400 has remained in nearly continuous production from 1978 until today, gaining fuel-injection, rubber engine mounts, and a front disc brake along the way. Our friend Ben Branch of Silodrome puts it best:

“There are good reasons why this three decade old design has survived and prospered. It’s not because it’s the fastest motorcycle out there… It’s because this is a motorcycle with soul, a bike with a personality that will keep you smiling as its engine transmits its charismatic thump-thump-thump into your chest.” —Silodrome

Yamaha SR400 Custom

Enter our new friend Nguyen Dinh Trung (@doti.ndt) of Vietnam’s DOTi Motorcycle — a garage he opened just six months ago. Nguyen’s story is one of hard work and bootstrapping his way up the industry ladder.  He grew up in a small town in Vietnam and began researching motorcycle customization all the way back in middle school. When he started his university studies, he had just $100 to his name but soon got into the business of making and selling motorcycle accessories.

“I used the money to buy a bigger motorcycle, a Suzuki Bigboy 250, which I modified with the help of my friends. I sold that bike for a higher price, and then did it again, working my way up to motorbikes with a higher capacity: CB400SS, SR400, Harley XL1200…”

Yamaha SR400 Custom

After graduating at the end of 2020, he opened his own garage, DOTi Motorcycle, with the help of his family.

“The garage has been open for 6 months, and now I have a lot of orders. Right now I’m working alone. All the work is done by me, shaping, welding, painting, wiring, etc.”

Yamaha SR400 Custom

The SR400 you see here is a 2000 model that Nguyen built to showcase his brand/garage. We love that it doesn’t follow any specific genre or style — it’s more of a high-spec roadster that retains the general silhouette of the original, yet little of the OEM machine remains. The bike showcases an arsenal of trick accessories: Yoshimura oil cooler, WM Prod Team fiberglass tank and metal electric box, WP steering damper, Ohlins shocks, Takasago rims, titanium hardware, and much more.

Yamaha SR400 Custom

For Nguyen, one of the greatest rewards has been the friendships he’s made across languages and borders:

“I’ve created an SR400 that many people have appreciated and enjoyed — friends from Thailand, Japan, and many other countries love this design.”

We love it here in the US, too, and we’re sure our readers from all over the world will feel the same. Below, we talk to Nguyen for the full details on the build, and we urge you to follow and support this new one-man shop on Facebook and Instagram.

Yamaha SR400 Custom: Builder Interview

Yamaha SR400 Custom

• Please tell us a little bit about yourself, your history with your motorcycle and your workshop.

My name is Nguyen Dinh Trung. I was born and raised in the small town of Di Linh, Lam Dong, Vietnam. I started to study and research vehicle motorbike modification when I was in middle school. When I was 15 years old, I had my first custom-made motorcycle, a Honda CL50. Since then I just like classic motorcycles.

I entered the university with a capital of $100 and got into the business of making/selling cheap motorcycle accessories. After a while, I decided I would take the brand name DOTi. I used the money to buy a bigger motorcycle, a Suzuki Bigboy 250, which I modified with the help of many friends. I sold that bike for a higher price, and then did it again, working my way up to motorbikes with a higher capacity: CB400SS, SR400, Harley XL1200…

So far, I’ve built myself a small garage with the support of my family. The garage has been open for 6 months, and now I have a lot of orders. Right now I’m working alone. All the work is done by me, shaping, welding, painting, wiring, etc.

• What was the bike’s make, model, and year?

Yamaha SR400, 2000.

I bought a used SR400 and custom made it to my liking — I don’t call it any specific style.

Yamaha SR400 Custom

• Why was this bike built?

I really like the simplicity of the SR400, it’s easy to customize. I decided to use it to help create the image of my garage. When people look at it, they will know that this SR400 is custom made by DOTi.

• What is the design concept and what influences the construction?

I didn’t follow any specific style — it’s just that I combined a lot of details to make my SR400 what it is.

• What custom work has been done to the bike?

I replaced pretty much all the parts, keeping only the frame, the engine, and the front forks. The rest of the parts are all purchased from Japan:

– Fiberglass Fuel tank by WM Prod Team Co Ltd, Japan.
– Electric box by WM Prod Team Co Ltd, Japan.
– Takasago Rims, H-type from a Suzuki ST400.
– WP steering damper.
– Ohlins rear shocks.
– Titanium bolts for all of the above details.
– And more!

• Can you tell us what it feels like to ride this bike?

The SR400 is a simple, kick-start bike. Just a fun and exciting motorcycle — the engine thumps like a heartbeat. The feeling when I ride my SR400 is awesome — there are so many people that turn their heads to watch.

• Is there anything done in this construction that you are particularly proud of?

I’ve created an SR400 that many people have appreciated and enjoyed — friends from Thailand, Japan, and many other countries love this design.

Follow the Builder

Facebook: www.facebook.com/DOTi.DL
Instagram: @doti.motorcycle
Instagram: @doti.ndt

3 Comments

  1. SRs make some of the greatest specials. This one is no exception. Pity that Yamaha, when planning to re-introduce the SR400, decided to go with a ultra bland, finish-it-yourself version. Nobody at the tuning fork factory thought to themselves .. “hey, everyone wants scramblers, street-trackers, cafe racers etc .. let’s offer one of those (or all 3) and in a larger, not smaller capacity!” Nope.

    • Couldn’t agree more with you on that. They missed the market on this one. Right now, the smaller displacement market has quite a few contenders here in the US: KTM Duke 200, CBR300, MT-03, and so forth. However, as far as I know there are no simple thumpers like the SR400, and that fact that Yamaha never developed it made it obscure and boring.

  2. Nice machine! I love hearing his story of hard work and ingenuity, very cool. Sr’s are always cool, and this one is loaded with cool stuff.

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