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Late-Model Magicmagic

Speed's Secrets, August 2008

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Late-model Harleys—the 2007 and 2008 bikes—are great platforms for certain performance modifications. That’s good news for the growing ranks of riders opting to keep their bikes a little longer now, hanging on to what they have rather than trading in for a newer version that’s, well, not much different. And definitely more expensive.
There’s no reason not to dig into these ‘07s and ‘08s for more power, either. And that includes even the newest ride-by-wire Electronic Throttle Control touring models. It turns out that they can be performance-modified and performance-tuned just like any other Harley. The performance gains can even be a little better than in the past. After all, you’re starting with more engine—a 96-incher.
Last issue Wayne Hanson of Speed’s Performance Plus pointed out the benefits of using a standard SPP “Stage I” tune-up on a late-model Harley, and we learned just how well these bikes respond to the normal performance upgrades associated with a Twin Cam. Modifications such as cam and piston swaps, addition of a Power Commander, and new pipes and new throttle bodies work wonders on the newer Harleys, just as they do on the earlier models, including the 88-inch Twin Cams and even the Evo. The result is a fast, smooth-running and ultra-reliable motorcycle that’s specifically built for the street.
For many riders a Stage I tune will be just fine, thank you very much. Pipes, filters, cams and a Power Commander will prove worthwhile, but Wayne goes on to say there’s even more potential for a late-model Big Twin. For starters, a 96-inch motor can easily become a 103 simply by installing big-bore pistons. The engine doesn’t even have to come out of the frame for the upgrade. These engines already have a nice 43⁄8"-stroke crankshaft—in itself a recipe for torque—so working from there it’s not much effort to lift the stock barrels and pistons off the case (those barrels and pistons have the same dimensions as the earlier 88-inch engines) and replace them with the same cylinders and pistons that would turn an earlier 88-inch engine into a 95. But because you start with a longer stroke, the result is a whopping 103 cubic inches. That simple bolt-in conversion of new camshafts, cylinders and pistons and a set of modified heads—which Speed’s also has and are also a direct replacement on the 2007-’08 bikes —results in a street-friendly motorcycle that produces anywhere from 110 to 120 horsepower. Quite a jump from the stock 70-or-so horsepower.

Speed’s has built and sold plenty of the 103” conversions and riders love ‘em. In fact, the Speed’s Performance late-model big-bore kits are a package. All components have been carefully selected and tested to complement the whole, and while the engine kits SPP assembles can match peak horsepower and torque numbers with most other big-bore kits, these engines really shine from idle to about 4,000 RPM. And as any Big Twin rider knows, that’s right in the sweet spot where most of the riding takes place. All components are top-quality, too. The pistons are JE (and Speed’s generally recommends a 10.8:1 compression ratio); the matching cylinder heads have reshaped and resized ports with valve sizes upped to 1.94” for intake and 1.63” on the exhaust, all for better flow; and the heads are assembled with new Comp Cams performance springs, collars and retainers.
Now for the bottom line. What does all of this cost, how long will it take to install and is it really worth it? As for the cost, figure around $3,500 for the parts, and if you have everything installed by Speed’s at a show toss in another $1,200 or so for labor. It can happen pretty fast, too. Done at one of the events—and Speed’s attends a lot of ‘em (check the schedule on their website)—the conversion can be completed during the event itself. It’s best, of course, to let them know ahead of time that you’re coming so they can schedule a specific time for the installation. And finally, is it worth it? Well, that depends on how much you’d like to have an engine with 110 to 120 horsepower and a lot of low-end torque. You can answer that question yourself the next time the light turns green and you twist the throttle.

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