2006 Dyna Superglide Sets Record as World's Fastest Harley-Davidson
Setting speed records at the Bonneville Speedway is a dangerous but addictive venture.
Hiro Koiso is a speed freak — of the salt variety. The Bonneville Speedway, located on the Bonneville Salt Flats of northwestern Utah, has lured racers since the early 1910s to pit their machines against the clock on the smooth salt straightaways. Koiso is no exception to the addiction and holds records for the world's fastest street-legal and open motorcycle class — all with his 2006 FXD Super Glide.
Master Technician at Red Rock Harley-Davidson in Las Vegas, Nevada, Koiso knows a thing or two about Big Twins. In 2011, at the BUB Speed Trials, Koiso set a record for the fastest street-legal Harley-Davidson with a top speed of 193.596 mph. In racing terms, 'street-legal' means that the machine must have a headlight, taillight, treaded tires, at least two gallons of fuel, and a starter.
Twin Cam Power
Koiso’s Super Glide is powered by a 135 cubic-inch JIMS Twin Cam with a ProCharger B-1 supercharger. Setting a record with the big horsepower FXD was something of a comeback, as the Koiso racing team suffered a crash in 2010. Koiso reflected about the setback, “This year’s preparation was tough but it was all worth it. I was so glad to be back on the salt to redeem myself.”
Racing is an unpredictable affair, especially at record-breaking speeds. Bad luck struck the Koiso racing team again in 2012 at the BUB Speed Trials. A fuel line fitting came loose during a run, causing a massive fire. Koiso was able to walk away from the accident, but it took the team a whole year to bring the motorcycle back to racing its state.
Although racing efforts were dampened by the weather, the Koiso racing team successfully campaigned the Dyna at the 10th annual BUB Motorcycle Speed Trials in 2013. The FXD was completely rebuilt and heavily-modified after the 2012 fire. While the Dyna still qualified for the 'open motorcycle' class, the team had built a fairing to also qualify for the 'partially streamlined' class.
Koiso's new fairing configuration proved to be a winner in 2013. Breaking the 200 mph barrier, the racing team set three new land speed records, including two AMA national records with a top speed of 214.342 mph in the partially streamlined, force inducted class. Despite rain cutting short the event, Koiso also made a single (non-record) pass of 198.941 mph without a fairing.
Due to weather and unfavorable salt conditions, racing at Bonneville was canceled in 2014, and in 2015. Bonneville is also an unforgiving arena. In 2016, the Koiso racing team suffered yet another major crash that required four months of recovery for Koiso. Undaunted, the team returned in 2017, focused on the non-streamlined or 'open motorcycle' land speed record.
True to their word, the Koiso racing team set a new world record for the open motorcycle class at the 2017 BUB Motorcycle Speed Trials. Cranking out almost four times the amount of horsepower than an average cruiser, Koiso managed to squeeze 227.236 mph out of the heavily modified FXD. The record officially makes Koiso's bike the world's fastest Dyna, and the fastest open motorcycle on the salt. Not bad for an old air-cooled pushrod V-Twin.
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