Custom Motorcycle: The World’s Fastest Street Sportster?

Custom Motorcycle: The World’s Fastest Street Sportster?

A rip-roaring, S&S-equipped Harley-Davidson beast

Jorgen Karlsson’s 2032cc Sportster never wins any shows—it’s a total sleeper. And most people who see it have no idea what they’re looking at. But the engine was built by Top Fuel drag bikerider and motor genius Charley Karling, and the bike has an incredible 163 rear-wheel horsepower!

“I’ve never dared let any of my friends test-ride my bike, it has way too much power,” Jorgen says. “You know, it delivers 100 hp at 3000 rpm! Nothing like a big Japanese four—that’s nice and civilized at low revs. Here the power hits you like a knockout punch, and when you back off the throttle the engine braking effect is equally violent. Charley Karling has gotten a test-ride, but he is used to 1500 hp nitro bikes so that’s a different story.”

Jorgen Karlsson is from Stockholm, and he works as an engineer and shipbuilder for the Swedish Navy. He’s very passionate about everything that involves technology. Among other things, he’s a member of the Vintage Fleet, a group of guys that keep old torpedo boats and other navy ships in shape and have their own harbor on an island in the Stockholm archipelago, so it was only logical to do the photo shoot there. In fact, it was Jorgen’s passion for engines and technology that made the bike so extreme.

“I want to try to push the limits of what’s possible, you know.” he remarks. Jorgen bought the Sportster, a 1993 XLH 1200, way back in 2004. The Swedish Harley-Davidson importer had given it a bit of flat track style to show off in the shop window on Stockholm’s main boulevard. He rode the bike for a few years before he got bored with the engine and started dreaming of a 100″ S&S Sportster engine. “I bought a 100-incher and put fuel injection on it, but I never got it running really right,” he says. “Worse, it wasn’t reliable. The pistons seized up twice, and there was a rattling noise from the cylinders. My engine-genius friend Charley Karling took the engine apart and found that the Axtell cast iron cylinders weren’t perfectly round, and the rear connecting rod wasn’t 100-percent straight. Maybe that engine would have worked OK for someone who would settle for revving it up to 5500 rpm—but I wanted at least 7000!”

Jorgen fixed the S&S engine and sold it. The tech head that he is, he had already started dreaming of the ultimate, no-compromise XL-type engine. When he started ping-ponging ideas back and forth with his friend Charley, he got the kind of feedback that convinced him to really give it a try. Both men wanted a dependable and strong engine with good fuel mileage. They decided on 4.125″ of stroke and 4.375″ bore, which adds up to 124″ (2032 cc), an over-square and rev-happy engine. “Also, Charley wanted to use as many S&S parts as possible. I told myself I’d better let him do as he wants to get the best possible results, which was exactly how it turned out.”

The boss at the S&S Racing Department is an old friend of Charley’s, which meant there weren’t any problems putting in orders for tailor-made stuff from S&S Special Applications: racing cases, heads with 2.2″ intake valves and 1.8″ exhaust, cylinders, roller rockers, and a Delphi VFI fuel injection, diameter 2mm x 51mm. The stainless exhaust system was TIG-welded by Jorgen himself. The cams are Red Shift 625 V2s, and the 8″ con-rods were special order from Carrillo. The JE pistons are also one-off. The cases were made for racing only and had no space for an alternator, so the guys put a three-phase generator from a Hayabusa inside the primary case.

World’s Fastest Street Harley-Davidson Sportster

Even with its relatively short stroke, the engine became too tall for the stock frame. The guys at Unique Custom Cycles in Stockholm replaced the top frame tube with a higher one in chrome-moly. In the back is a Metmachex aluminum swingarm and a pair of Ohlins HD 143 shocks; up front is an ISR-Ohlins front fork in custom-made triple trees. The aluminum rims are from Akront, and the hubs and brakes are also from ISR.

“My front brakes, 230mm ISR discs with six-pot calipers, are officially the most powerful motorcycle brakes in the world,” Jorgen says. “I can lock up the front wheel going 100 kmh!”

World’s Fastest Street Harley-Davidson Sportster

With the paint job and final assembly taken care of, it was time for the maiden voyage. Jorgen had a high pulse rate as he got into the saddle and clicked into first gear. “We had tried to create a civilized engine, and it ran nice and smooth at low revs,” he reports. “But, of course, there are huge gobs of horsepower. You have to handle that throttle grip with a lot of respect. It was literally shocking to begin with but now I have gotten used to it.”
In 2014 Jorgen put his super Sportster on the dyno and got the result: 163 horsepower and 195 newton metres of torque. Three times the stock output! So is the headline to this article true? Is this really the fastest street Sportster in the world?

“Of course, you can never be completely sure,” Jorgen admits. “I know there is another 124-incher in the USA, but it doesn’t seem to be built as good as mine. A guy in the north of Sweden has a 120-incher, and there is also an American 137-incher, but I think it only runs in Pro Street drag racing.”

To sum things up, Jorgen has created a very extreme bike that looks so discreet that a lot of folks don’t realize what they’re looking at. Doesn’t it frustrate him that a lot of people think it’s just another slightly modified Sporty?

“Well, if I park my bike next to a flashy long-fork at some show, I won’t be the winner,” he says. “Sure, it feels a little unjust. But I get a lot more appreciation from those who really understand what this is all about. That’s good enough for me!” RC