A motorsport composite tech builds a carbon-fiber cafe racer…
Unveiled in 2015, the BMW G310R represented the company’s foray into the sub-500cc streetbike market. The entry-level roadster is powered by a 313cc liquid-cooled single-cylinder engine good for 33.6 hp, utilizing an unusual reverse cylinder layout — the intake is at the front of the engine, the exhaust at the rear. Reviews for the 349-lb thumper have been mainly positive, noting the bike’s build quality, chassis stability, fuel economy, and fun:
“A bike meeting BMW’s standard for quality that belies its $4750 price tag.” —Cycle World
Enter Michael Horn, a UK-based motorsport mechanic and composite technician who has 25 years of experience working with teams in the highest echelons of motorsport:
“World Rally, F1, endurance racing, World Rally Cross and Formula E for teams such as the Subaru World Rally Team, Brawn GP, Mercedes F1, and most recently Multimatic Motorsports Europe with the Ford GT’s at Le Mans 24Hr and the Mazda DPI prototype in the US.”
Michael has been a great admirer of custom bikes, particularly BMW cafe racers, but the extensive travel required for his work kept him on the road and out of the shed. Until 2020, that is…
“I was due to travel extensively to the USA for racing; however, covid travel restrictions meant this was not possible and sidelined me to a factory-based role, here in the UK.”
After coming across the DK Design BMW G310R we featured here on BikeBound in 2018, Michael decided on one of these pint-size roadsters as his donor:
“They are a relatively cheap bike to purchase, with an easy frame to modify with the rear section being bolt-on, there are very few conversions of this bike in Europe and I wanted something a little different and I started to look for a bike.”
He bought a lightly used donor, commuted on it all summer, then tore it apart as soon as the rains started to come down, working through the details of modifying a 21-century bike with fuel injection, liquid-cooling, ABS, Lambda sensors, and more:
“With most cafe racers, the final pictures rarely show the level of work hidden from view, this bike was no exception.”
Given Michael’s background in carbon fiber, it’s no surprise the bike is littered with one-off carbon parts: the headlight brackets, radiator side covers, exhaust heat shield, chain guard, rear number plate bracket, race number panels, and more. As for the tank, he took a mold from an R100 tank and built a carbon fiber cover that conceals an alloy fuel tank, battery, new alloy expansion tank, and a reworked airbox.
We’ll let Michael himself give you the rest of the details on build.
BMW G310R Cafe Racer: In the Builder’s Words
This BMW cafe racer was built by myself in Oxfordshire, UK, as a shed build and is my first go at building a custom bike.
I have been a motorsport mechanic and more recently composite technician for over 25 years, working for high level teams in World Rally, F1, endurance racing, World Rally Cross and Formula E for teams such as the Subaru World Rally Team, Brawn GP, Mercedes F1, and most recently Multimatic Motorsports Europe with the Ford GT’s at Le Mans 24Hr and the Mazda DPI prototype in the US.
I greatly admired the BMW R80/100 custom bikes by WalzWerk Motorcycles and Reynolds Custom Motorcycles and also the CCM Spitfires (with there extensive machined alloy and carbon fibre). However, the extensive travel involved in global motorsport meant I had very little spare weekend time for riding bikes or starting a project build.
This year I was due to travel extensively to the USA for racing; however, covid travel restrictions meant this was not possible and sidelined me to a factory-based role, here in the UK.
With time on my hands, I started to look for a project bike and I saw on the internet, the DK Design BMW G310R from Taiwan where he’d fitted an R80 tank to it, they are a relatively cheap bike to purchase, with an easy frame to modify with the rear section being bolt-on, there are very few conversions of this bike in Europe and I wanted something a little different and I started to look for a bike.
I actually found and purchased an R100 tank before the bike and then purchased the BMW G310R, which was two years old with 800 miles on the clock — the salesman thought I was nuts when I said I intended to take the hacksaw to it as soon as I got home. However, the project was delayed for some months due to the fantastic summer weather in the UK and I used the bike for commuting, until the first day I got wet on the way home from work, the toolkit came out that night!
Below are some details on the build…
With most cafe racers, the final pictures rarely show the level of work hidden from view, this bike was no exception. Once I had stripped the BMW of its extensive array of plastic panels, I soon realised that fitting the R100 tank was way more involved than I had thought. I needed to use the stock G310 fuel pump/sender unit, which is housed within the tank and the stock fuel cap. The R100 tank was now going to be just a cover and so instead of cutting up a perfectly good tank, I took a mould from it and manufactured a carbon fibre cover, concealing beneath it an alloy fuel tank, battery, new alloy expansion tank and a reworked airbox. The cover is secured with the BMW tank badges, which where turned on the lathe from alloy bar stock and laser-etched.
Once the tank was done, I turned my attention to the seat frame. I purchased a basic rear hoop from eBay as I did not have access to a tube bender and then modified this with extra tubing to the design required to give enough space for all the electrics and ABS unit beneath the seat. A pair of Highsider proton Indicator Stop Tail Light Combined units are concealed within the seat frame; I made the seat pan and outsourced the leather seat trimming.
As it is my job to work with carbon fibre, I had to have some on the bike. Although the tank I decided to paint as the bike didn’t look retro enough with it in carbon fibre, I made from carbon: the headlight brackets, radiator side covers, exhaust heat shield, chain guard, rear number plate bracket, and the race number panels. The original framework for the rear foot pegs was cut down and modified to give the illusion that they were designed from new to hold the race number panels.
The exhaust is a combination of original pipework, retaining the Lamba sensor, but with the G310 being reverse cylinder it was then re-routed under the engine to meet up to a shorty silencer followed by a slash cut exit pipe. After welding it was painted with Cerakote Piston-Coat ceramic spray coating and wrapped in titanium exhaust wrap.
Other features include pedals and foot pegs modified to billet style, new ACE handlebars, bar end mirrors, bar end indicators, 7” LED headlight. The original LCD dash was retained and is now housed in a CNC machined alloy billet housing, designed to replicate two round old school clocks.
As the bike was virtually new in terms of mileage, forks/rear suspension, engine, wheels/tyres, and brakes are all standard and untouched — electrics are only modified to suit the rear lights.
The tank cover, seat frame, hugger, and front mudguard (RnineT) are finished in gloss black within the original rear peg frames changed from silver to a satin black alongside the front mudguard brackets (again RnineT).
Most of the unused brackets have been removed; however, one holds the retro 1977 tax disc, which is a homage to the age of the fuel tank, and another to hold a remote battery connection, to save having to take the fuel tank cover off to charge or jump start the battery if ever required.
I have not given the bike a name but would suggest that the r now stands for re-imagined.