Custom Build: Josh Mott Racing ’79 CX500

MotorcycleUSA Staff | August 7, 2014
Back February 2013 I was wandering around the One Show in Portland just after the doors opened on Saturday morning, getting in before the second round of revelry kicked-off to take a closer look at the machines on display. There were beautifully-built bikes scattered throughout the downtown warehouse, but a modest purple-tanked CB450 Nighthawk held its own with a sporty, flat-trackesque aspect that, more than anything, looked like a blast to ride. A little card on the bike stand indicated that this was the work of Josh Mott Racing, a bike shop out of Boise, Idaho.

We chatted a bit about the Nighthawk and left it at that until the following year when I got in touch again to see if he would be showing anything at the 2014 show. Mott sent along a picture of a 1979 Honda CX500 Custom he’d just completed that was even more enticing than the Nighthawk, so I chased him down by phone to get the scoop.

To start with, Mott is an avid off-roader, racing desert events, on dirt ovals and everywhere in between when he can tear away from work. Some of his earlier projects, like the Nighthawk and a 1981 Honda GL1100X Gold Wing dual sport, allude directly to his personal riding preferences, but the CX500 is a completely road-focused machine. He’s not all that interested in street riding, but building motorcycles has become a serious outlet for his two-wheeled passion and the allure of making a CX look bitchin’ was too tempting a thought to refuse.

The CX bug was planted when Mott started noticing an uptick of the Honda retros on the customs scene, and it didn’t take long for him to develop an appreciation for the look of the engine – a V-Twin mounted across the frame. After that the design wheels started to turn and he began to plan what he’d do if he had one to customize, so asked his go-to boneyard resource to keep an eye out for any CXs.

The 1979 Honda CX500 Custom as it looked fresh from the boneyard.
The 1979 Honda CX500 Custom fresh from the boneyard.

They soon spotted a ’79 Custom, though it was trashed. Here’s what Mott has to say about the condition of the donor bike:

“It was pretty roached. It had been sitting for a long time, and in my head I was like ‘whoa, this thing is pretty rough, do I even want to do anything with this bike?’ I went ahead and did a compression check and checked for spark, it had both of those. Then I cleaned the carbs, just a patch job to see if I could keep it running and it fired right up and ran so I said ‘alright, I’ve got something to work with.’”

He got the bike back to the shop and stripped it down. The engine required a full rebuild, and Mott quickly discovered some of the quirks of the CX’s design. Overall, the mill was in pretty good shape, aside from the fact that the cam chain shoes were broken. A clean and polish and new water pump later he was ready to put the engine back in the frame. When he fired the bike, however, the water pump immediately went out. According to Mott’s father, Randy, who’s been in the motorcycle business since the ‘60s and runs the shop with Josh, this is a common issue with CXs.

Thanks to the design of the engine just about any maintenance work, like replacing a water pump, requires the powerplant be pulled completely out of the frame. Another design aspect to cause some frustration is the placement of the ignition coils, which are located right underneath the gas tank. There’s a rubber heat protector under the tank to help keep the gas cool, but heat gets trapped in there over time and eventually knocks the ignition coils out, according to Mott.

After the headache of getting the engine dialed, Mott created an exhaust which he started to imagine as soon as he saw the splayed heads of the Honda V-Twin. The result is two symmetrical header pipes that swoop out and behind the engine to a single point underneath the seat, with spent gasses pushed through a megaphone canister on the back.

One of the biggest challenges with the new exhaust setup was moving the airbox and electronics that sit under the seat on the stock machine. To open the space up Mott built a custom battery box underneath the engine to house all the bits that needed to be moved and ran the wiring down the frame.

Mott then turned to designing the fender, which he formed through trial and error with paper templates until finding a shape he liked. The tank is a stock CX500 Custom, though the tail is a custom piece. The front end screen/headlight mount/dash are custom fabricated as well. He wanted a single unit to hold the headlight, speedo, key switch, and dash so began bending sheet metal, molding it first around the bucket of an XS650 headlight. He then made places for the dash and key switch, finding that there was still enough room on the right side for the choke as well.

“It took me a couple of days,” explains Mott. “I started on it as an idea and got committed so just went ahead and finished it. It actually came out pretty good, but I won’t do it that way again. There’s easier ways of doing what I accomplished and it’ll be a lot cleaner next time.”

From early on in the project, Mott wanted whitewall tires and knew that a clean look could be achieved using black powder-coated Comstar wheels. But he also wanted to put his unique touch on that element, so decided to drill holes around the rims every two inches. Mott then designed a special tool to highlight the holes, giving each a “dished-out” look. Braking components are stock, though with a smaller master cylinder on the front and new shoes on the spruced-up unit out back.

The front suspension required some time to get right because Mott wanted the CX to have a more aggressive streetfighter stance. He had to ditch the stock triple clamp setup because it set the bars close to an inch-and-a-half higher than the top of the clamp, giving a sort of chopper-inspired taller front end. So he went back to the boneyard until he found a CL360 unit that fit perfectly and immediately cut the distance between the top of the clamp and the bars. Out back he grabbed two Ohlins shocks that were an inch longer than stock and was nearly there. He pulled out the internals of the forks and shortened the springs a bit to get things just right.

Paint work was all done in-house as well. The CX marks the first time JMR has done its own painting on a project, a point they’d reached after a few bad experiences sending pieces out.

Mott’s next project brings him back into the realm of off-roaders, somewhat, with a customer requesting work on an XL250. It’s currently missing the rear portion of the frame, and the owner is asking for a hard-tail board-tracker. Should be a cool one to see once it’s all done.

If you want to check out more of Mott’s work, head over to the JMR Facebook page or check out the Instagram feed where many of his new projects make their debut.

Oh, and in case you were curious about how the CX500 rides and sounds, check out the video below to see the machine in action.

Josh Mott Racing 1979 CX500

Mott modified the front end to get the stance right  and added inch-over-stock-length Ohlins shocks out back. Detail of the exhaust. The exhaust was one of the first features Mott imagined when rebuilding the CX500.
Custom exhaust pipes meet underneath the seat of the restyled CX500  ending in a single megaphone. The CX500s engine needed a good clean and polish  so Mott stripped it down for a full rebuild. Josh Mott stands with his creation.