Guy Morden - Harley-Davidson XR750

"I was driving home from a local motorcycle shop when my buddy Jim turned to me and asked if I wanted to build an XR750. I thought about it for a minute and said 'well now I do!' I had always been a fan of XR's but had never considered owning one until that moment." Guy says it was as simple as that. Jim put the idea in his head and the rest is history. Well, not quite. This was just the start of a multi-year journey. 

"The most successful race bike of all time"

Harley-Davidson started making the XR750 in 1970 to replace the outgoing KR750. Harley was starting to lose ground to other manufacturers on the dirt oval and they needed a new machine to compete with the faster and lighter import motorcycles. The 1970 and 1971 XR750, with its iron heads, were prone to overheating and lacked the power of their competitors. The problem was quickly remedied in 1972 when Harley-Davidson re-designed the engine with a bigger bore and shorter stroke (same displacement) and new aluminum heads and cylinders. From there, the XR750 went on to win 29 out of 37 races from 1978-2008. Not only is it the most successful bike in AMA history, but it is also often considered the "most successful race bike of all time!" 

By the 1980's Harley realized that most race teams wanted the motor but they were putting them in different race frames. So they stopped offering complete motorcycles and only kept producing the XR motor. Over time, the XR750 community has become a small and tight-knit group. Guy tells me that most XR people don't really want to sell their parts. Instead, they prefer to trade for other XR parts. That way they are never down on XR inventory. Luckily for Guy, Jim already had an XR and knew some of the people he thought they should talk to first to start accumulating the parts for Guy's bike. 

They started by reaching out to Chris Evans (the Canadian flat track rider, not Captain America) and were able to purchase a side-shock C&J frame from him. Next came the pipes, tank, and wheels from the Canadian multi-time champion, Don Taylor. The engine came from Flat Track racer Randy Texter's collection. Guy and Jim drove down to Boston to retrieve it. The engine may have been the last 'big piece' but they were still missing a lot of parts. Over the next few years, the hunt for parts would take Guy and Jim on road trips as far as Texas.

When the last thing they needed was the rockers and hadn't had any luck tracking them down yet. Guy and Jim decided to take a few days and drive through a portion of the United States. They did a loop through New York, Pennsylvania, Ohio, and Michigan. Stopping at every Harley-Davidson dealer they could find to inquire about XR parts. In Ohio, they met a fellow named Geo. It turned out, Geo had lots of XR parts, including the rockers they needed. He wasn't interested in selling the rockers, but true to form in the XR750 community, he was willing to swap for other XR parts. After some discussion, they agreed on swapping the rockers for a set of 1980 XR pipes. A few weeks later, Guy made the 5 hours drive back to see Geo and make the swap. He now had all of the XR750 parts he needed.

Once they got started on assembling the bike, Guy and Jim had some ideas about how they could improve the bike. Custom triple clamps were designed by Jim and manufactured off-shore. A set of Honda CBR600F4I forks were used but first, they turned down the lowers on a lathe to remove any tabs. They then sent the forks to Accelerated Technologies in Buckhorn Ontario for a complete rework. Guy also sent a bar, mocked up to the ideal length, to them and had them make a custom rear shock that can be adjusted for high and low-speed compression as well as rebound damping. The risers were then custom-made by their friend Stark and the handlebars were made to their specs locally by Almost Oldschool Motorcycle Co.

Some of Guys' favorite parts are the ones that Jim designed and printed on a 3D printer. Like the all-new sump. Jim also came up with a one-of-a-kind ignition system which eliminated an impressive 9 lbs! The new system gets rid of all the intermediate gears, spindle, bearings, spindle mounts, stators, and rotors. They achieve this by running the ignition off of the number 4 cam. The cam has a shaft welded to it that extends through the cam cover. The cover itself has been machined to accept an oil seal and they 3D printed new covers and a mount for the new ignition. The ignition itself runs off of a very small 4-cell Antigravity battery which is tucked away behind the front number plate. 

When the day finally came that the bike was complete, they rolled it outside Guys' workshop. After roughly five years, many miles of driving around and searching for parts, more hours of working on the bike than they could count, and an undisclosed amount of money. Guy threw his leg over his XR750 for the first time and fired it up. He rode it up and down the laneway in front of his house. After watching XRs sliding around the dirt oval and winning races for longer than he could remember, he was now riding his own XR750. He brought the bike back to the shop and handed it over to Jim to take it for a ride. Once Jim had taken it up and down the laneway a few times, his daughter asked if she could go for a ride. She got on the back of the bike and Jim took her for a slow ride down the lane and back. Just as he was cresting the hill on the way back to Guy, it all went bad. Jim rolled off the throttle and Guy could hear right away that the motor sounded horrible. Jim cut the engine and coasted the bike back. He suggested they pull the motor right away and see what had happened. After giving it some thought, Guy decided he wasn't ready to dig into it to see what had gone wrong. They rolled the bike back into the workshop for the night. 

They later found out that the front cylinder exhaust valve had stayed open when the piston came back up. It totaled the piston, head, and cylinder. The engine had blown on August 9th, 2018. Guy wouldn't ride the bike again until the summer of 2020. Ultimately, the valve issue set him back a few thousand dollars and undoubtedly, some heartache. Eventually, the bike was repaired and broken in at Shannonville Motorsport Park. It has since been raced at Welland County Speedway as well. Guy was over 40 by the time he started racing Flat Track. He says, "I remember watching old footage of Kenny Roberts flat tracking. There is something about sliding out the back wheel and dragging your foot. Nothing beats the sound and spectacle of flat track racing!" In regards to the XR750 specifically, he says. "I can't think of any other motorcycle that is better looking, but I can think of a million other motorcycles that are more practical to have." 

You can see Guys' mid-90s era Harley-Davidson XR750 at Perth County Moto. It is on display as our window bike for the month of January.