‘79 Honda CX500 – MR Motorcycle
Written by Martin Hodgson.
For nearly 30 years the Honda CX500 cruised the highways and byways of the world as a poor man’s cruiser, for those who couldn’t shell out the bucks for a Harley Davidson but still wanted the bars up style and the V-Twin heart beat. Then in the last ten years some clever folks around the world took the odd ball Honda, so ugly it was known as the “Plastic Maggot” and started turning them into a stunning line up of customs that just keep getting better. Enter Mathieu Renaud of MR Motorcycles in Montreal who picked up this 1979 Honda CX500 Custom for the bargain price of just $1000 (Canadian) and put his years of experience in aeronautics into creating one of the cleanest and well put together CX customs we’ve ever seen.
Mat is not the first aeronautical engineer to be involved in a CX500 build, in fact the designer of the CX500 was Shoichiro Irimajiri an aeronautics master who spent more than 20 years at Honda designing F1 engines, the legendary CBX 6 cylinder and of course the plastic maggot. He was given a blank canvas for the CX project and rather than stick with an inline four engine that was becoming the dominant unit of the period he bucked the trend creating a water-cooled, shaft-driven, V-twin mounted like a Moto Guzzi. At the time Honda had never produced a V-twin, had only once used a shaft drive and to keep things interesting Irimajiri opted for pushrods over overhead cams and rotated the heads 22 degrees so the carbs would be in the centre of the bike.
One of the reasons Mat started Mr Motorcycle was to find a way to best spend his time during the long winters in Quebec. Judging by the quality of his work it is time well spent but a CX for a thousand bucks needs a lot of work to get it to this level of quality and it all started with a full strip down and examination of the parts. Coming from an aeronautical background anything that didn’t pass the test was tossed aside and only the good bits remain, largely the frame, tank and wheels. Mat cleaned up the frame and started working on a way to make clean lines out of the pressed steal rear end. A lot of people simply cut it off at the shock mounts and then weld in a rear hoop but Mat was having none of it and cut the frame right back to the downtube. From here the new metal work is all tubular with a new rear subframe beautifully integrated into the main frame and the shock mounts moved to the lower supports.
With the frame, shaft drive and many smaller components out to powder coat Mat could think about how he was going to tackle the metal work. The Custom model of the CX is often overlooked by modifiers due to its ape hanger bars and gaudy seat but it comes with a distinct advantage, it features a fuel tank considerably narrower than the behemoth that is the stock model. The tank has been body worked to perfection and the latched fuel cap restored to original condition. With the frame back on his bench he then fabricated a tail-piece that matched the clean lines of the tank, with long and low the name of the game. The rich dark green paint work has been laid down flawlessly on the tins and neon lime pinstripping provides a unique approach to showing off just how good the metal work is. With the Mr Motorcycle logos added to each side of the tank in white that’s all the colour there is to the build as Mat lets his fabrication skills do the talking.
Getting the lines right on a CX500 is crucial to the look and the consensus from the top builders has been to keep the back bone near parallel to the ground with about 2-5 degrees of downward angle at the rear. To get that look Mat shortened the front forks 1 1/2 inches and the retention of the heavily bobbed, tyre hugging, fender aids in front end rigidity. The standard steering stem and bottom yoke has been retained but clamping the lowered forks up top is one of Cognito Moto’s brilliant billet aluminium triple trees. With the change to the rear subframe of the bike Mat needed far shorter rear shocks to get the stance right and blacked out adjustable items do the job perfectly. The single front disc has been retained, although drilled for increased cooling and to help apply some extra pressure a master cylinder from a Honda CBR600RR provides a far better feel at the lever.
That modern Honda braking componentry sits on the new clip ons next to a smorgasbord of the very best components from Motogadget. It’s all controlled by the very impressive m-Unit that is the heart of the system and hidden away out of sight. The tiny m-Button keeps the bars ultra clean while there is no need for a key thanks to the wireless ignition courtesy of the m-Lock. A pair of m-Switch housings control the bar end LED indicators also from Motogadget. While the housing on the other side of the bars switches the new Cafe Racer look headlight between Hi and Lo Beam. There is an LED strip tail light/indicator combo and neat bar end mirrors and just when you thought the Motogadget catalogue had been emptied, Mat binned the horrible CX instruments in favour of a Motogadget Motoscope Classic Tachometer that also features a small digital display. He even went to the trouble of neatly remounting the choke so that it’s both in a functional location and becomes another neat touch to admire.
And yet despite all Mat’s incredible work so far the defining feature of any CX500 build remains the unique design of the engine by Irimajiri-san, you just can’t fight it, and Mat has done an amazing job in making it look beautiful and work with the rest of the build. The 497cc, OHV, 80° V-twin, with 4 valves per cylinder remains relatively stock internally but has been treated to hours of polishing and powder coat to get it looking its best. The heavy stock collector box has been thrown away and now individually wrapped pipes run rearward where they vent to atmosphere courtesy of twin black reverse cone mufflers. But it’s the stock carbies that are one of the standouts, cleaned and polished to within an inch of their life, anyone who’s played with Keihin carbs can appreciate Mat’s work. Fitted up with pod filters and the addition of the free-flowing exhaust causes a CX to lean out and rather than just throw random jets at it and hope for the best Mat had his machine professionally dyno tuned so it’s perfect.
If the engine was a talking point of the CX design so too were the Comstar wheels that were used on a number of Honda models at the time. Love ’em or hate ’em they definitely look best in black and the lightweight wheels that are functionally superior to many that replace them wear quality Dunlop rubber on Mat’s ride. Which is really what sums up everything he has done in turning out one of the cleanest, most thoughtfully put together, CX500 Cafe Racers you are ever likely to see. From the brilliant body work and paint, to the frame modifications that allow for that glorious engine displaying negative space and the detail to which every single item is presented at its best shows that the only thing better when it comes to a CX build is not one man qualified to build a spaceship, but two; and as the ice melts Montreal is about to witness this incredible Honda take flight.
[Photos by Jean-Sébastien Dénommé]