40th Anniversary Edition: 2023 Yamaha RZ350!

What if Yamaha and Bimota teamed up to build a 40th anniversary RZ350? 

That’s the question San Francisco-based engineer and road racer Julian Farnam asked himself. Of course, that would entail combining the legendary liquid-cooled, YPVS-equipped two-stroke parallel-twin from the Yamaha RZ350 — one of the baddest street-going smokers of all time — with a bespoke chassis, revised geometry, and modern suspension, brakes, wheels, and more. 

It wouldn’t be the first Yamaha-Bimota creation — Jon Ekerold won the 1980 350cc World Championship on the Yamaha-powered Bimota YB3, after all. However, since such a machine obviously wasn’t in the cards for the 40th anniversary of the ’83 RZ350, Julian set out to create his own “2023 Yamaha RZ350.”

Julian was uniquely prepared for the project. While he designs electric farm tractors by day, he says he’s just a big kid at heart who likes to build things, and motorcycle chassis design has always fascinated him. In fact, his first big project back in 1990 was his Yamaha A-N-D FFE 350, featuring an experimental forkless chassis with a Yamaha RZ350 engine!

Around 2000, Julian started his own frame company — A-N-D Vehicles — and began to produce a Kawasaki EX500 chassis kit called the AK-1, which saw a good deal of success on the track:

“Quality was apparent, and there were definite shades of Bimota in the brightly painted trellis spars mated to milled alloy rear plates. The AK-1 competed in AMA Pro Thunder and AFM Twins, with some notable victories in AFM – A-N-D framed bikes took 2nd and 3rd in 2001 and won the championship in 2002.” –Silodrome

There was a lot of talk around a similar trellis-style frame kit for the RZ350, but when nobody put their money where their mouth was, Julian decided to take matters into his own hands:

“About four years ago I said ‘fuck it’ and decided to build one for myself just because I wanted one.”

The entire chassis — frame, subframe, swingarm, etc. — is all custom-built, with an asymmetrical frame design that allows larger diameter expansion chambers to be run on the right side of the bike.

Julian goes into the full process in his 30-page build thread on BARF (Bay Area Riders Forum), with everything from his initial design sketches to the full execution of the bike you see here — including all of the many detours, challenges, mistakes, lessons, and triumphs along the way.

The bike weighs in at just 290 pounds with a half tank of gas and makes an estimated 75 hp from the 375cc Tony Doukas Racing engine. While Julian hasn’t ridden the bike as pictured yet, he has logged over 600 miles on a prototype with the same geometry:

“I often refer to the handling as ‘telepathic.’ It’s almost as if the bike knows what to do with very minimal rider input. It is an absolute joy to ride!”

Julian’s “2023 RZ350” was a stand out from this year’s One Moto Show, and we can’t wait to see what this Bay Area mad scientist turns out of his workshop next.

Yamaha RZ375: Builder Interview

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

I grew up riding both dirt and street bikes in the 70s and 80s. By my mid-20s I was road racing on RD400s and RZ350s. I still ride as much as I can. But to be honest, I probably spend more time in my shop than on a bike.

My educational background is in transportation design from Art Center College of Design. I currently work as a mechanical engineer for a company that manufactures electric farm tractors. But inside I’m just a big kid who likes to make stuff.

For some reason I’ve been particularly interested in motorcycle chassis design. I’ve spent countless hours studying how motorcycles do what they do. I’m particularly interested in alternative suspension configurations and am a huge fan of people like Tony Foale, James Parker, Nico Bakker, Normal Hossack, and others who have developed alternatives to the modern telescopic fork. My first big moto project was an experimental forkless chassis also powered by a Yamaha RZ350 engine.

In my own moto work I tend to wear two hats. Often, I take the role of a scientist, or more accurately a mad scientist. I am wanting to try new and unconventional things just to learn and see what happens if I try something weird. Then with other projects I’ll put on my engineer’s hat and apply best practices to create something that will perform at the highest level.

I live in the San Francisco area and have spent most of my career commuting via public transportation. This has allowed me to spend much of my commute time filling sketch books with motorcycle concepts. From sketches, I quickly convert my ideas into CAD. From there it’s (usually) an easy transition to building parts.

From early on, I’ve always wanted a well-equipped home shop. After buying my first house, I started accumulating tools and equipment. My two favorite machines are my Hitachi 2M horizontal mill and a Victor 16 x 30 lathe. The Hitachi has very rare vertical head that came as a factory option. It’s a large machine and the vertical head makes it very versatile.

The Victor lathe has a relatively short length relative to the swing diameter. It is perfect for making motorcycle parts. I’ve even used it when making my own wheels. I’ve also got a basic Bridgeport mill, a 20” Apex sander, a 250 amp Miller “blue box”, and a bunch of other basic metal fab tools.

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

That’s a funny question. The engine is from a Yamaha RZ350, but there never was a “donor bike” per se. That said, there are parts on this bike from a Yamaha R6 (tank and seat), Suzuki GSXR and SV650 (forks and wheels). Major components like the frame and swingarm are all scratch-built and unique to this bike.

• Why was this bike built? (Customer project, company promotion, personal, etc.)

This was a “well, fuck it” project. After the success of my AK-1 race bikes back in 2001/2, I’ve had several people asking about custom RZ frames. None of those conversations resulted in bikes getting built. So about four years ago I said “fuck it” and decided to build one for myself just because I wanted one.

That said, I’m actually building three and one has already been delivered to Tony Doukas for his team to do some track testing. The third bike will be built with a few minor changes. If I decide to build more and offer them for sale is yet to be determined. I’ve certainly got interest, but I need to catch my breath at this point and evaluate how I want to proceed.

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

The concept was kind of a “what if”… what if Yamaha and Bimota teamed up to build a 40th anniversary RZ350? Of course that never happened, so I made my own interpretation.

• What custom work was done to the bike?

The entire chassis (frame, sub-frame, swingarm, etc) are all custom-built. The tail is also a custom piece and has a long story as to how it was developed. I could and have written many pages on how the bike was built. (Details can be found in my build thread on BARF.)

• Does the bike have a nickname?

It’s an AY-2…but most people won’t know the significance of that designation, so I just call it a “2023 Yamaha RZ350.”

• Any idea of horsepower, weight, and/or performance numbers?

Tony Doukas who built the engine has an identical engine that is making around 75 hp. He is confident that I should expect the same. That’s not bad for a bike that tips the scales right around 300 lbs.

 

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

The bike as pictured hasn’t been ridden yet, however I have logged over 600 miles of California backroads on a prototype bike that was built two years ago to test the geometry. That bike is amazing to ride. It is super flickable through tight twisty stuff, yet still very stable at higher speeds. I often refer to the handling as “telepathic.” It’s almost as if the bike knows what to do with very minimal rider input. It is an absolute joy to ride!

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

With the frame I wanted to follow the geometry of my AK-1 race bikes from 20 years earlier, but with a little bit of a refresh. I pulled lots of inspiration from Bimota without copying anything directly. I’m very happy with the results.

I also wanted to design a tail that looked like a Yamaha part and matched the design language of the R6 tank, yet also be unique to this bike. I went through many ups and downs in the process… I liked the direction, then didn’t, then liked it again, then didn’t like it. In the end it came out perfect and the graphics also worked out really well with it.

• Is there anyone you’d like to thank?

• Brian Turfrey Racing for the awesome expansion chambers.
• Tony Doukas for the RZ375 engine.
• Rick Fitgerald / Aerocraft for the fiberglass tail.
• Anthony and Alex at Monarch Tractor for help with the 3D scanning.
• Bobby Keith / Cycle Finish for the amazing paint work.
• Brad Wood / Motodemic supplied the super high tech headlights.
• Ken’s Garage for the Penske shock.

And my amazing wife Laura for allowing this craziness to intrude into our lives!

Build Specs

• Wheelbase: 1410mm (55.5″)
• Swingarm Length: 585mm (23″)
• Rake: 21 Degrees (Yes, it’s that steep!)
• Weight: 290 lbs (with 1/2 tank gas)
• Weight Distribution: 55% F / 45% R
• Seat Height: 810mm (32″)
• Notes:
  • Asymmetric frame design allows for larger expansion chambers on the right side
  • Rear suspension geometry based on the TZR250-3XV design

Follow the Builder: BARF (Bay Area Riders’ Forum) Build Thread