A 1450cc street weapon inspired by the legendary XR750…
The Harley-Davidson XR750 remains one of the most dominant racing machines in the history of motorsports, no matter the number of wheels. The “most successful race bike of all time,” the mighty XR won 29 of 37 AMA Grand National Championships between 1972 and 2008. It also competed in road racing, hillclimbing, and was Evel Knievel’s preferred jump bike.
“The XR750 has become widely considered to be the most successful race bike in motorcycle racing history, perhaps the greatest vehicle in motorsports history. Is there even any competition? What other machine boasts a half-century reign spent transforming talents into heroes and heroes into legends? And best of all, this legacy might not yet be fully written.” —Cycle World
As recently as 2017, 47 years after the bike’s release, AFT racer and friend of the blog Jeffrey Carver, Jr. won the Lone Star Half Mile on an XR750, and some flat track legends believe the XR750 could still win. Last year, in order to commemorate the bike’s 50th birthday, Harley-Davidson commissioned filmmaker Evan Senn of Fast & Left to create XR750: 50 Years of Wins — a film that traces the remarkable history of this machine, featuring a script written by Gary Inman of Sideburn.
Enter our new friend Max, a veteran racer who’s competed in motocross, speedway, and road racing on both two and four wheels. To him, the irony of the XR750 proved irresistible:
“The XR seemed an anathema to me: a cosmic joke machine, produced by a cruiser company, that became the winningest machine of all time. Next to the Cosworth DFV, the XR750 reigned, cold hard on the opposition, year in, year out. I felt drawn to it: as sculpture, as performance, as a cosmic joke.”
The bike you see here began life as an ’02 Sportster — Max’s race bike, which found “new and interesting ways” of telling him to quit racing it. For instance, melting the Halls sensor, spitting white-hot oil on the rear tire, and high-siding him with alarming frequency.
“It wasn’t that I grew tired of falling. But I borrowed a Halls sensor from a South African Hells Angels rider — you know, to get me through the last race in the series — and of course it melted. I thought, this is a new one: being cornered in the pits by a Hells Angels chapter. End of racing duties.”
With the Sporty freed of racing duties, Max decided to transform the bike into an XR-inspired street machine. In fact, he’d owned an original XR750, though it never seemed proper to set up an authentic XR for street use:
“I thought Evel was excellent form when I grew up. Mert, too. I had an original XR750 that I never used. I always think street set-up XR750s look a bit forlorn, like a thoroughbred taking children on rides up the beach.”
Very little is left of the original Sportster, even the frame has been cut and braced to achieve the right head angle. The 17-inch supermoto rims were swapped out for Maxxis-wrapped 19-inchers, and Paul Holbrecht (@holbrecht.p) engraved Max’s family crest into the engine cases.
The engine has heads provided by none other than Mert Lawwill (true unobtainium items), as well as cylinders/pistons/pushrods/ignition/etc. from Daniel Dunn of NRHS Performance — one of the best-known names in hot-rod V-twins, who recently closed his doors. Says Max of the powerplant:
“The setup should be good for 115bhp, but for longevity I have wound the revs back and I run it at 90bhp.”
The power proved too much for several rear hubs — finally, Max found a solution that may interest other builders dealing with high-torque machines:
“Rear hub has an Excel cushdrive. I grew tired of ripping out the standard Harley hub.”
As for the riding experience, it makes quite the impression on even the most veteran V-twin hot-rodders:
“The engine builder took it up the street and he said: ‘First I opened the throttle and then I shit myself.’ I generally ride it pretty sedately.”
Below, we get the full details on this incredible “XR1340” from Max himself.
XR1340 Street Tracker: Owner/Builder Interview
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
Primarily, I race cars these days, but long years ago I started on motocross and then speedway. The XR seemed an anathema to me: a cosmic joke machine, produced by a cruiser company, that became the winningest machine of all time. Next to the Cosworth DFV, the XR750 reigned, cold hard on the opposition, year in, year out. I felt drawn to it: as sculpture, as performance, as a cosmic joke.
• What’s the make, model, and year of the original donor bike?
To build a nice Harley, you buy a Harley, keep the VIN number and reg, and throw the rest away. This bike says it started its life as a Sporty in ’02. There is truth in here but front to back, the cycle parts of the machine include:
- Maxxis tyres and Excel Takasago rims.
- Motocross shocks from a 450 Suzuki.
- Beringer brakes.
- Magura brake master cylinder.
- Flat tracker bars.
- The tank is handmade in steel.
- Seat unit.
- The frame is a Sporty but it has had to be cut and braced to enable the head angle.
- The pegs are motocross pegs.
- The swingarm is by Metmachex.
- Nitron shocks.
- DID chain.
- Rear hub has an Excel cushdrive. I grew tired of ripping out the standard Harley hub.
The engine might or might not be 1450cc. Whatever it is, it’s more than 1200cc.
- Mert Lawwill provided the heads – not available now.
- Cylinders, pistons, pushrods, ignition module, etc. from NRHS – speak to Daniel Dunn.
- Dell’Orto carbs.
- The oil case was cut down.
- Derby cover engraved with my family crest.
- An alloy oil tank was fabricated
- Screaming Eagle oil cooler.
- Supertrapp exhausts.
- K&N filters.
The set up should be good for 115bhp, but for longevity I have wound the revs back and I run it at 90bhp.
• Why was this bike built?
I had the Sporty as a race bike. Now I hurt in the places I used to play. Pushed hard, the bike would melt the Halls sensor and white-hot oil pumped out the front of the engine. The early indication that this had happened was a high-side. Oil over the rear tyre and a corner don’t mix. This would happen at least once every four races. It wasn’t that I grew tired of falling. But I borrowed a Halls sensor from a South African Hells Angels rider – you know, to get me through the last race in the series – and of course it melted. I thought, this is a new one: being cornered in the pits by a Hells Angels chapter. End of racing duties.
• What was the design concept and what influenced the build?
Form follows function. And it wasn’t functioning as a racer. Time for form. I thought Evel was excellent form when I grew up. Mert, too. I had an original XR750 that I never used. I always think street set-up XR750s look a bit forlorn, like a thoroughbred taking children on rides up the beach.
• Does the bike have a nickname?
Open to offers here. It should have a name. Probably “Veteran” like me.
• Can you tell us what it’s like to ride this bike?
The engine builder took it up the street and he said: “First I opened the throttle and then I shit myself.” I generally ride it pretty sedately. When I turn up the wick, I am reminded of Hildo: https://youtu.be/vjFeC7g6_40
When pushed hard, it becomes happier and will slide front and rear. I suppose more because it weighs quite a bit.
• Was there anything done during this build that you are particularly proud of?
The proportions look right to me. I like my family crest on the engine cases.