No XS: Yamaha XS400 Twin(s)

Yamaha XS400 Cafe

Introduced in 1976, the Yamaha XS400 was highly anticipated in the industry. After all, its two-stroke sibling, the RD400, had been the fastest of the 400s, and everyone was curious what Yamaha could do with a 400cc four-stroke.  While heavier and less sporting than the RD, the XS posted respectable numbers for the day. The SOHC straight-twin engine made 36 horsepower at 8500 rpm, capable of pushing the 400-lb machine to a top speed of 96 mph, while the squarish styling recalled the Italian sport machines of the era.

Yamaha XS400 Cafe

Enter Aaron Lopas of Detroit, who’s spent most of the last few years focusing on sports cars, modifying and racing a wheel-to-wheel car. However, a recent trip to AMA Vintage Days changed that:

“I also raced motocross many years back and re-fell in love with motorcycles after attending AMA Vintage Days at Mid-Ohio with my best friend from those old dirt biking days.”

Soon thereafter, Aaron started looking for a project bike, preferably a midsize twin — a bike for in-town riding, with decent factory styling. Says Aaron:

“I have to some extent moved beyond the horsepower wars, and look and feel and lightness is as important to me as performance.”

Yamaha XS400 Cafe

He found the perfect donor in this 1977 XS400. It wasn’t running, but it was local, low mileage, and the tank was pristine. As you can see from the photos, Aaron took a different tack than many of the bikes we see, preferring to salvage as much of the original styling as possible:

“The build concept was to leverage the good OE looks, but change the not-so-good like the super long seat and the usual large lights, mirrors etc.”

Yamaha XS400 Cafe


We especially like how he retained the factory tail, but shortened the seat pan, subframe, and seat itself for a more compact profile, with a new seat cover from Scott Lynch at Meanwhile, the front-end and cockpit were streamlined and minimized, as were all of the lights and fenders, which gave the bike its nickname: “No XS.” The result is a bike that makes you do a double-take, as you try to put your finger on why it looks so much better than the original:

“It’s the sum of all that detail work that makes the bike in my view.”

What’s more, the bike can quickly transform into its flashier alter-ego, “Little Chromer,” with a set of chrome custom fenders and other bling.

Yamaha XS400 Cafe
“Little Chromer” setup.

Below, we get the full story on these XS400 Twin(s).

Yamaha XS400 Custom: Builder Interview

Yamaha XS400 Cafe

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

I live in the Detroit area and have been into design and building, whether it’s buildings or vehicles, for many years. Mostly in recent years I’ve concentrated on sports cars — I modified and raced a wheel to wheel car, but I also raced motocross many years back and re-fell in love with motorcycles after attending AMA Vintage Days at Mid-Ohio with my best friend from those old dirt biking days. I have a home garage workshop, which has a car lift, but I have space in it enough for working on bikes too. I’ve already bought another bike for my next project. (I’m hooked!)

Yamaha XS400 Cafe

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

1977 Yamaha XS400 — found the original bike locally, inexpensive as it was not running but had only 7k miles and tank was in perfect condition.

• Why was this bike built?

It was built for a fun project, and for personal use as largely an “in-town” bike — literally to go to the coffee shop, but also health club etc. etc., and just to ride, enjoy, and share with other enthusiasts.

• What was the design concept and what influenced the build?

I wanted a donor bike that had good looks to start with and wanted a small to midsize twin, as this is classic cafe racer, and as I have to some extent moved beyond the horsepower wars, and look and feel and lightness is as important to me as performance. These years of XS happened to have a fantastic squarish gas tank and a nice tail section stock, so the build concept was to leverage the good OE looks, but change the not-so-good like the super long seat and the usual large lights, mirrors etc.

Yamaha XS400 Cafe
Before / After.
• What custom work was done to the bike?

Since I believe it’s important to have good fit up of seat to tank and since I love the stock tail, I shortened and sectioned the stock seat pan and reused the stock foam, but modified it to fit the modified pan and lowered its height. The bike’s frame was shortened to allow fit up of the new seat. A custom cover was made by Scott at Bad Ass Bike Seats.

Yamaha XS400 Cafe

The whole upper front end was redone — a 5 ¾” headlight was mounted on custom brackets I made which don’t clutter the forks, and allow everything to package including the custom-made “dash” which houses new mini speedo and tach from Dime City/Mikes XS.

Yamaha XS400 Cafe

I did lower bars, bar end mirrors, a smaller much less ugly master cylinder, and levers without mirror holes too.

Yamaha XS400 Cafe

I also came up with inexpensive but custom solutions to get small turn signals front and rear using some repurposed shapes and tube with standard LEDs.

Yamaha XS400 Cafe

When it comes to the exhaust and fenders I ended up with a main look which has a shortened, painted and striped front fender to match, no (except inner) rear fender and shorty modified slip ons.

Yamaha XS400 Cafe

I also have a second way to run the bike with more chrome with a fantastic old Kaw 10/2 front fender and a rear hugger made from a front SR400 fender with custom made bracketry, and the stock megaphones for exhaust.

Yamaha XS400 Cafe
“Little Chromer” setup. Chrome fenders, stock megaphones, etc.

Many other changes were made including removing excess (hence “No XS”) like the rear footpegs and frames they were on, chain guard, etc., and it’s the sum of all that detail work that makes the bike in my view.

• Does the bike have a nickname?

I call the project XS400 Twins(s) as I have the two ways I run it — the main look is called “No XS” and the alternate look is “Little Chromer.”

• How would you classify this bike?

I guess I would say cafe racer but it’s a little more upright and the seat, while very different, isn’t quite as minimal as most cafes. So it’s really kind of a “perfected” standard or naked bike.

Yamaha XS400 Cafe

• Was there anything done during this build that you are particularly proud of?

Mostly that I did everything myself in my shop with my tools except the seat cover, and while I have done extensive sports car work, I had not done motorcycle stuff in a long time. The front end packaging was a particular challenge I am proud I did not give up on ‘til I got the look I wanted with my chosen components.

Follow the Builder @aaronlopas


  1. Bike looks great. You diffidently accomplished your goals.

    • Thank you Frank – there are quite a number of bikes where some of the OE design elements are great and can be leveraged and perfected and these square tank XS 400s fill that bill….

  2. Appliedscienceguy

    Had one of those in 1990-Bought mine for 500.00 in Tempe Arizona -Exact dame color and trim!!!

    • Tempe AZ 1990 and a little red XS400 sounds like a great place time and bike in your journey – hope is was and happy motoring

      • Ross Mason

        I may acquire one of these soon. How did you reduce the seat length and maintain the OEM look? Solid bike!

        • Aaron Lopas

          Hey just saw this comment, in case you see my reply, I cut the stock seat pan both to shorten length and width, cut the stock foam and shortened and reshaped it, and cut and shortened the frame….but by using the stock pan it guaranteed tail would fit up and seat would fit to tank properly…

  3. Richard Rozario

    Hi, I’m Richard Rozario an Indian presently living in Perth, WA. Yamaha enter the Indian market after Honda. Honda focused more on their legendary 4 stroke bikes as a lot of Indians are obsessed with fuel ecnomy. On the other hand, there were quite a few enthusiasts who loved 2 stroke motorcycles. There was Jawa, a Czechoslovakian company whose motorcycles were manufactured in India by a company called Ideal Jawa Limited. There was Royal Enfield with their flagship model called the Bullet which was a 350cc 4stroke engine in the powered bikes category. Yamaha launched the RD 350 in collaboration with Escorts Motors Limited. Probably the timings weren’t right as sales were a bit low. They worked on getting their 100cc motorcycle called the RX 100 which was a craze in the market as it boasted of excellent pick up, beautiful design and the USP of this motorbike was that it was low on maintenance. I was lucky to buy one in 1994 and it is still alive and kicking. It had a good ELF( Engine Life Factor) which others lost on. During it’s heydays- it was everywhere. It ruled the rally scene, motocrosses and all other events. It outclassed the Kawasaki Bajaj RTZ and IndSuzuki AX 100.
    Sadly, it ceased production as the Government introduced emission laws which this model couldn’t sustain. But it brings me fond memories whenever I ride it. I wanted to get it over here but the rules won’t permit me to ride it over here on the highways.

    Thank You

    • Aaron Lopas

      Hi Richie thks for your response my bike and your memories of your Yamaha in your home country. i actually bought this bike stock (the “before” picture) from an Indian fellow who lives here now. Meeting him reminded me of a few trips I took to India on business and what a huge motorcycle market it is. Motorcycles seem to be a big part of so many people lives as a good form of transportation there, but its also nice to hear of your passion for your bike beyond it being just for transport. I hope you have a motorcycle here, and if not you get one soon! Happy motoring…

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