Project Lethe: BMW R100 Cafe Racer

BMW R100 Cafe Racer

For many of us, building and riding motorcycles is crucial to our mental and emotional health. Whether it’s the ability to swing a leg over the saddle and crack open the throttle, letting the wind clear away some of our daily troubles, or the satisfaction of working with our own hands, motorcycles offer freedom, focus, and healing far out of proportion to their size and cost. It’s like that old Winston Churchill quote, slightly revised:

“There is something about the outside of an [iron] horse that is good for the inside of a man.”

BMW R100 Cafe Racer

This is certainly the case for our new friend Marshall Hewitt (@mrshlhwtt), a mechanical engineer who became obsessed with BMW boxers while working on his first build, a CB750K. So he picked up a 1988 BMW R100, nicknaming it “Project Lethe” after the river Lethe from Greek mythology, whose waters were known to erase the memories of the dead. After they’d drunk of the river and forgotten their past lives, they be reborn.

BMW R100 Cafe Racer

It was an especially appropriate name for the build, as Marshall built the bike during a hard time for him personally:

“Completely rebuilding motorcycles provides me that mental ge away I need, even though some of it can be frustrating. I know it’s just a motorcycle, but I’m blessed to have had the resources to rebuild this BMW in the middle of this storm. This bike may have been reborn into something it wasn’t before, but so was I. This motorcycle was my river Lethe.”

BMW R100 Cafe Racer

He did all of the work himself, including the fabrication, welding, painting, engine rebuild, wiring, tuning — everything but the upholstery and powder coating. And what a fantastic job he’s done, creating a minimalist German cafe racer that not only turns heads, but is lighter, faster, and much more nimble that the original:

“It’s a new experience driving an unguarded BMW being cognisant of just how close those wonky cylinders are getting to the ground!”

BMW R100 Cafe Racer

Below, we get the full story on the build from Marshall himself, as well as more photos from photographer Dan Johnson (@hoosier_sc).

BMW Cafe Racer: Builder Interview

BMW R100 Cafe Racer

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

My name is Marshall Hewitt, I am a mechanical engineer with a strong passion for motorcycle building. I love re-imaging the look of classic Japanese and German motorcycles while still honoring their original designs. On my builds I do as much of the work as I can, which typically includes engine rebuilds, fabrication, painting, wiring, tuning, etc. — only outsourcing the purchased parts and powder coating while learning new skills along the way (currently getting proficient at TIG welding.)

BMW R100 Cafe Racer

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

Ever since I first saw my first cafe racer, I became infatuated with the stripped down look, especially in the modern era where the bike appears minimalistic but still contains upgraded features, particularly on-board programmable controllers. Being a mechanical engineer who works with automation daily, building fully featured cafe racers hiding all the electronics was an instant passion once I bought my first CB750k. I am constantly building and creating, rarely letting myself sit down long enough for a meal. Project Lethe was built as my second personal build after my first, Norma Jean, a 1981 CB750k.

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

I have a habit of falling in love with ugly/weird things, and the first time I saw a BMW boxer engine I was put off at the thought that anyone would like such a funky offset engine like that. Naturally, over the year building Norma Jean, my hate for the boxer engine became an obsession, I HAD to build one. The R series is truly the perfect platform for cafe racers. Leaning into the weirdness: offset engine cylinders, pegs, exhaust runs and intake inlets, single-sided mono shock, etc., I absolutely wanted to showcase this. That big hunk of aluminum had to be the focal point of the build.

BMW R100 Cafe Racer

Most paint it black and never get to see the original paint scheme of the engine as it’s usually hidden by a fairing, so I wanted to honor the way BMW painted them, except for the front engine cover, which I painted black and gave an accent line in aluminum. I wanted it to look like an engine, a tank, and wheels; bare bones, but with no compromises. The tank would be classic black so as not to draw attention away from the engine, with the normal BMW pinstriping — the logo being almost stock with only the blue being replaced by black.

BMW R100 Cafe Racer

I named this bike after Greek Mythology’s river Lethe; the place where those reborn into a new life drink from so that they are no longer weighed down by the events of their past life. 2021 going into 2022 was the hardest year of my life, having to face something I’ve spent the past 14 years trying to protect myself from. It’s hard to heal from something that takes so long to distance yourself from, so all you have during is distraction. Completely rebuilding motorcycles provides me that mental get away I need, even though some of it can be frustrating. I know it’s just a motorcycle, but I’m blessed to have had the resources to rebuild this BMW in the middle of this storm. This bike may have been reborn into something it wasn’t before, but so was I. This motorcycle was my river Lethe.

BMW R100 Cafe Racer

• What custom work was done to the bike?

Donor Bike: 1988 BMW R100
Frame: Stripped, cleaned and powder coated
Body: Refinished tank, seat and subframe from Walzwerk, hidden battery box under swing arm
Motor: Complete rebuild for engine and carbs, modified airbox
Exhaust: MCU split headers, Sport-Evolution exhaust kit, HAT TECH muffler
Brakes: Front full brake rebuild, stock rear drum brake
Controls: ABM raceClips, Brembo Brake, Domino Clutch, Walzwerk throttle, Highsider mirror, Biltwell grips
Wheels: Powder coated stock wheels, Michelin road classic tires (110/80-18 front, 130/80-18 rear)
Front Suspension: Shaved fork legs, lowered (3in)
Rear Suspension: YSS Topline 410mm
Electronics: M.unit blue controller, Firepower feather weight battery, M.blaze disc and Highsider turn signals, M.button switches, Motoscope Tiny

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

The stripped weight is noticeable, as this 980cc bike gives exactly what you ask of it. The fully rebuilt engine is extremely responsive while the drivetrain, also fully rebuilt, feels very smooth. It’s a new experience driving an unguarded BMW being cognisant of just how close those wonky cylinders are getting to the ground!

BMW R100 Cafe Racer

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

The custom exhaust composed of components from MCU, Sport-Evolution and HAT TECH. It’s a clean stainless steel racing exhaust that merges under the bike and exits on the left side of the bike. The exhaust wraps around and hides the battery mounted behind the engine and under the transmission, painted aluminum to look like a natural extension of the engine.

BMW R100 Cafe Racer

I am proud of the work that I can claim as mine for this build; I did all the fabrication/welding, painting, rebuilding, tuning, wiring, etc. The only notable third party work was the seat from Walzwerk Motorcycles (I haven’t ventured into upholstery yet) and powder coating.

BMW R100 Cafe Racer

Follow the Builder

Builder IG: @mrshlhwtt
Photographer IG: @hoosier_sc


  1. Vorrei comprare la bmw r100 verde. Sono italiano. Mi sapete dire il prezzo?

    Grazie buon lavoro

  2. That Boxer is simply stunning! You have retained the classic black with white pinstriping. The seat is my favorite part. It has a beautiful curve. It fits the whole silhouette of the machine. By golly… it even looks remotely comfortable. What a beautifully simple cafe racer!

  3. Marc Devereaux

    Sir,,very nice build indeed..however you rear fender has fallen by the way side..from personal experience, I can help you retrieve your missing part..simply retrace your route, watching closely along the side of the tarmac..good hunting sir.

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