1958 Harley-Davidson Sportster XLCH
Claimed power: 55hp @ 6,300rpm (approx.)
Top speed: 115mph
Engine: 883cc air-cooled OHV 45-degree V-twin, 76.2mm x 96.85mm bore and stroke, 9:1 compression ratio
Weight (wet): 480lb (218kg)
Fuel capacity/MPG: 1.9gal (7.2ltr)/40mpg (est.)
Price then/now: $1,265 (approx.)/$7,500-$12,500
Competition improves the breed, they say. And while the 1958 Harley-Davidson XLCH Sportster was born of competition stock, its engine capacity eschewed the very type of racing its direct ancestors were designed for. How come?
To answer that, we have to go back to the mid-1930s, when racer and Motorcycle Hall of Famer Reggie Pink helped draw up the rules for production-based track racing. As he was also a British bike dealer, Pink advocated for fair competition between American brands and imports. The result was AMA’s production-based Class C, which allowed overhead valve bikes of 500cc to compete against sidevalve machines up to 750cc — or 45 cubic inches. Harley-Davidson developed the famous WRTT specifically for this class.
But it was post-World War II competition from lightweight British parallel twins that motivated the Motor Company to develop a new 45-cubic-inch street bike, but still with one eye on Class C racing. The result was the Model K of 1952, a unit-construction 750cc 45-degree V-twin in a lightweight (for Harley, anyway) chassis with modern telescopic fork and swingarm rear suspension. The engine retained sidevalves for Class C homologation purposes, and the competition KRTT version ruled Class C until Dick Mann’s Grand National win on a BSA in 1963.
The Sportster XL
But in spite of a capacity increase to 888cc for the KH and KHK, the flathead K bikes couldn’t match the performance of the new overhead valve British 650s. Harley embraced the inevitable with the 883cc overhead valve Sportster, and in doing so, the company acknowledged two things: Overhead valves were the way forward, and the Sportster was not going Class C racing anytime soon. The KRTT would soldier on until Class C rules were changed for 1969, prompting the development of the Sportster-based XR750.
The Sportster was launched for 1957 as the Model XL, essentially a new overhead valve engine in slightly modified Model K running gear. The iron cylinders used a new 3-inch bore with the 3-9/16-inch stroke from the Model K — a stroke dimension that remains in all Sportsters to the present. Iron heads with hemispherical combustion chambers topped the cylinders, with valves operated by pushrods and rockers. Each pushrod had its own single-lobe camshaft, the four arranged in an arc inside the timing chest and driven by a half-time gear that also turned the ignition timer.
A single Linkert carburetor fed the engine, which drove a chain primary to a multiplate clutch and 4-speed “trapdoor” gearbox (the geartrain could be removed without splitting the cases). Final drive was by chain on the right side, and in a break with Harley tradition, the foot shifter was also on the right with a one-up, three-down pattern like British bikes at the time. Early models had a cast alloy outer primary cover embossed with “Sportster,” but this was later abandoned for a simpler pressed-steel item.
The dual-downtube chassis connected to 18-inch wheels by a telescopic front fork and dual coil spring/damper units attached to the seat subframe. Eight-inch drum brakes provided stopping power. The XL produced an estimated 40 horsepower, and as tested by Cycle magazine, turned in a 15-second quarter with a top speed of 101mph. This compared well enough with the 42 horsepower 1957 Triumph Tiger 110 at 16 seconds and similar top speed.
With deeply valanced fenders, a generous 4.4-gallon fuel tank, a large headlight and a subdued exhaust, most reviewers assumed the XL was intended just for touring. All that would change in 1958.
The XLH and XLCH
A year before Triumph introduced the Bonneville in 1959, Harley had a rocket ship of its own. Although the Sportster’s 883cc capacity was too big for Class C, it was fine for open Class TT racing.
U.S. TT was nothing like the Isle of Man version and more of a cross-country steeplechase. In the late 1950s, Triumph Trophy Birds, BSA Catalina Scramblers and Matchless G80s were very competitive, challenging the KRTTs and leading to the development of the race oriented XLR.
With higher compression (around 9:1) and larger valves, the XLR also used a trick frame with thinner walls and lighter weight. It also sported the now famous “peanut” gas tank borrowed from the S range. Ignition was by magneto. And as the increased power could be produced reliably, it made sense to produce a “customer” version. This became the 1958 XLH. The XLH was essentially an XL with the XLR’s cylinder heads, though the castings were slightly different — long reach spark plugs for the R, short reach for the H. Everything else was as the XL.
The 1958 XLCH was a far more radical departure. The “CH” designation, quite logical in Harley-speak (C for stripped bodywork, H for high performance), was variously interpreted as “Competition Hot” or “California Hot Rod.” Though not an XLR, it could have almost passed for one. The stock XLH was stripped of its lights, mufflers and other extraneous items (though lights and a license plate bracket were available for an extra $60), the fenders were bobbed and the peanut tank fitted. The idea seemed plain: Here was an over-the-counter hot rod you could ride to the desert or track, compete in a TT race and ride home again — as long as you did it in daylight.
Sportsters weren’t big sellers in 1958, with the Sportster range outsold four times by the big twin FL range and almost three times by the humble 165cc 2-stroke S range. According to Harley-Davidson, of 12,676 Harley-Davidsons sold that year, just 1,529 were XL variants: 579 XLs, 711 XLHs and 239 XLCHs.
The XLCH reappeared in the catalog for 1959, but in a completely different guise. Mufflers and lights were back, although the performance modifications and magneto were retained. The 1959 XLCH also sported a new, smaller headlight with the now-classic “eyebrow” cowling and a high-level exhaust. It proved to be the most popular XL model with 1,059 sold, compared with 947 XLHs (coil ignition and low exhaust but with the high compression engine) and just 42 base-model XLs.
Performance numbers quoted at the time are inconsistent, but it seems likely a good 1959 XLCH was making around 55 horsepower at the crank and weighed around 490 pounds wet, compared with 46 horsepower and 430-440 pounds for the Triumph Bonneville T120 introduced that same year. The XLCH would turn 14-second quarters at faster than 90mph; the Bonnie’s performance was similar.
Mike Quinn’s Sportsters
Mike Quinn lives in Coos Bay, Oregon, and has a collection of more than 100 Harley-Davidson motorcycles, including seven XLCHs. “I tried to get the whole line up of CHs,” Quinn says. “I had the ’58, ’59, ‘60, ’61, ’62 — I do not have a ’63, a ’64 or a ’65. The ’58 is basically a built-up bike. It came as a ’58, but when I started looking into it, almost everything was wrong,” Quinn says. “It had good numbers on the cases, but I ended up taking everything off it and getting all the right stuff, then putting it back together.” The restoration took two years.
“The preparation work, determining what is correct — parkerized versus cadmium, paint versus chrome, etc. — takes a lot of time,” Quinn says. “Often just waiting for the motor or parts to get back from chroming or painting seems to take forever. The most difficult parts to find were the rear fender, the 18-inch rear Grasshopper tire and the correct peanut gas tank. Most of the parts came from swap meets.”
Quinn eventually found the correct rear fender in Canada, while much of the hardware came from now-defunct NOS Parts and Old Dude Vintage Parts & Service in Atlanta, Georgia. Local Harley dealers were particularly useful, Quinn says. The engine was rebuilt by Doyle’s Harley-Davidson, now in Eugene, Oregon. Owner Mike Doyle and Gene Walker of Salem Harley-Davidson both helped with the project. Coos Bay painter Greg Sweeney applied the glossy black and white paint.
What makes the XLCH so special to Quinn? “Well, more than anything I guess I like the way they look. The first one  of course was an offroad competition bike. And the second one, all they did was add the lights, horn and the high pipe, basically kept the same thing. I like the peanut tank, the Grasshopper-type tires. I just think they’re cool looking motorcycles,” Quinn says. “It’s a little different [from a big twin] since the shifter and brake are on the opposite side. I’m not used to that. I don’t like it, because in a panic situation it’s difficult to remember. It’s not a smooth ride, it bounces, but they’re fun bikes. They have reasonably good power as long as you don’t compare them to today’s bikes.” MC