While ground up builds that push the boundaries of design and engineering are great, its the less ostentatious projects that often win me over. Take for instance this Honda CB500 cafe racer by Sinroja motorcycles. To the untrained eye the bike could be mistaken as simply a clean vintage Honda, but in reality, a hell of a lot of work was done to get it looking this good. The project started out with an incomplete and badly neglected bike but with with a bit of Sinroja ingenuity and craftsmanship, it has been given an entirely new lease on life.
In the case of this Honda cafe racer build a lot of the parts used were transplanted from other motorcycles. This is because much of the donor bike was incomplete, including the engine itself. Engine overhauls are a standard procedure of all Sinroja builds so this didn’t worry the brothers all that much. The build kicked off with a customary engine rebuild or at least rebuilding the parts they had. Once the block had been seen to the cylinders received larger 61mm pistons pushing compression up to 11.5. The CB500 heads were one of the missing components so in their place Sinroja retrofit a set from a CB650. For even more additional power gains a high lift cam and new valves were also installed.
Carburetion is new too with the engine being fed by a row of 650Z carbs wearing K&N filters. Each carb was painstakingly re-jetted to optimise its performance with both the filters and the entirely new exhaust system. The exhaust is a 4-into-1 system put together using CNC bent header pipes and a Cone Engineering muffler. Sinroja then optimised combustion using their pulse-jet ignition add-ons. The resulting overall performance increase is a significant 20bhp which gives this CB500 a final power figure in excess of 65bhp. Not bad for a 40-year-old bike that weighs a fraction of its former self!
Sinroja are also sticklers for balanced bone lines so this CB500 frame is far from standard. All that remains of the stock chassis is the main loop. The subframe extends straight back with only a slight kick up at the rear loop. The passenger foot-peg mounts were also redesigned for a more visually appealing finish and a full set of foot-pegs fabricated for both the rider and pillion. Perched on the frame is the original fuel tank but behind it sits a custom made seat. After shaping the foam the seat was covered in some off-cut leather from a Bentley and diamond stitched with gold thread to match their theme. The seat was designed to allow a passenger so to prevent it from appearing too long the rear third is covered in perforated leather.
Sinroja workshop partner Towzatronics handled all the Honda’s electronic upgrades. The wiring harness is a custom setup and runs all the best bits from the Motogadget catalogue. These include bar end indicators, an M-unit, keyless ignition and push button switches. The small rear indicators are by Rizoma and double as running/brake lights. The headlight is a 7 inch unit from Reno. For a super clean cockpit, Sinroja has also installed a tiny MST Speedster gauge that’s set into a Fastec Engineering top yoke. The bars wear Motogdget grips and the throttle is a classic Domino item.
To further emphasise the bikes classic appeal the stock rims were replaced by flanged Akront aluminium items and wrapped in Firestone rubber. The rear brake remains a drum unit for looks more than anything else, but up front, they installed a second disc for plenty of stopping power.
The icing on this cake is definitely the understated classic paint scheme laid by GD Design. All of the black paint, including the layer on the frame, has been flaked with 24 karat nanoflakes. This gives the Sinroja CB500 cafe racer a warm golden glow in direct sunlight. A classic gold leaf Honda emblem on the tank and matching Sinroja logo on the filler finish things off.