Why the BMW Boxer Air-Cooled Engine is Perfect for a Custom Cafe Racer

The day I bought the BMW R80/7 - First photo

How’s it going folks? My name’s Marcus and welcome to the montmoto blog. I’ve created this blog to document me stripping down a 1979 air-cooled BMW R80/7 motorcycle to each individual component and then rebuilding it into my dream bike. My hope is that folks will be able to follow along on this journey, help me make some of the design decisions along the way and ultimately maybe encourage some people that have always dreamed of taking on a project like this - to just give it a go. So let’s do it. :)

Who Am I?

I have been riding motorcycles since I was 16 years old. I’ve had most types of bikes - starting with my first 50cc Suzuki CP50 scooter. Although it was just a small bike, I was instantly hooked on the freedom and in the moment feeling you get from riding on two wheels. Those of you who ride or have ridden bikes know that feeling - being able to reach out and touch the world around you as you move along. And yes, I know I’m talking about an old 80’s 50cc scooter when I say this. But It’s a unique feeling I’ve never experienced from any other thing.  Since my first scooter I’ve had a couple of other Vespas (ET4 and 300GTS Super), a loud cruiser (250cc Yamaha Dragstar) naked street bikes (Honda CB400 and Honda CBF600) and more than a few big bore Adventure bikes (BMW R1150GSA and right now I own the R1250GSA). 

Throughout this time, I have always wanted to build my own custom motorcycle. A couple of years ago I restored a Vespa scooter which gave me the confidence to give an even bigger project a go.  And that’s where this blog comes in.

BMW R80/7

I’ve bought a 1979 BMW R80/7 Airhead and I’m going to spend the next (however long it takes) restoring it, and customizing it to make it my own dream motorcycle.

I’m hoping for those of you interested in taking a similar journey that this blog might inspire you to give it a go and custom more or restore your own dream motorcycle. I’ll be creating blog posts and videos as I go to help people follow along. So let’s get down to business. 

Selecting a Motorcycle

It all started in January 2019 when I decided I wanted to restore an old motorcycle in my garage in the back garden. I quickly narrowed my search to the BMW R series of air-cooled models (known as ‘Airheads’ as opposed to ‘Wetheads’ for the later liquid cooled models). I knew I wanted an old bike because:

1. I knew it would likely be easier to do without all the computers and electronic components in a modern motorcycle and

2. somewhat from a romantic standpoint, I wanted a bike that was as old as, or older, than me. I turned 40 this year - so just chalk it up to a mid-life crisis. 

The reason I picked an air cooled boxer has 3 parts to it: 

(1) Boxer Engine

The boxer engine was first created by Karl Benz in 1897 and was frequently using in aircraft more so than cars. The most famous use of a Boxer engine is likely the VW Beetle which used the air cooled rear mounted  engine in it’s design from 1938 to 1982 when it switched over to water cooled. A notable mention is also Porsche, with the 911 exclusively using boxers from 1964 until present day.

Sometimes called “Flat Engines” or “Horizontally Opposed”, the Boxer Engine is basically a V-engine with pistons 180degree apart so they stick out the sides directly opposite each other. There are several different types of Flat Engines but what makes it a Boxer is that the pistons shoot in and out at the same time, so they both “punch out” from the crank at the same time and both meet in the center at the same time and is analogous to boxers touching gloves at the start of a bout. This gives the engine a very distinctive feel and the boxer wobble/ vibration which many of us love.

Boxer engines were particularly suited to early motorcycles due to the cylinders and cooling fins sticking out to the sides, offering lots of airflow to the cooling fins prior to the introduction of liquid cooling. Additionally, the engine offers a nice low center of mass - which as you know allows for a more stable, controlled ride.

(2) Availability Parts & Advice

The second reason is I live in Berkeley in Northern California and these Airhead BMW’s are easy enough to come by. A quick search of Craigslist on any day will bring up a couple of different options. Beyond that there are old BMW specialists still making new parts for these old motorcycles such as Boxer2Valve, Euromoto Electric and for custom parts Cognito Moto. More on these in later blog posts. And finally there is a good community of enthusiasts online to help answer my questions and steer me when I get lost. Resources like www.adventurebikerider.com and www.Airheads.org are incredibly invaluable if you want to see for yourself.

(3) Looks Amazing

Finally and being honest, most importantly, it looks incredible. That boxer engine sitting in front of your shins as you vibrate sideways down the road is exactly the kind of perfect bike I want. It sounds great, feels great and was a no brainer for me. 

In my next blog I’m going to go through finding the right bike for the right price, what to look out for when buying one of these old R80/7’s as well as some of the things I wish I knew at the time. So if you’re interested in that, sign up to the mailing list and I’ll see you in the next one. :)