01 Here is S&S’s 4-3/8-inch stroke flywheel assembly (MSRP $1,249.95). The flywheels are CNC-machined from heat-treated, closed-die, steel forgings, and the assembly is pressed fit together.
After 10 years of solid performance out of his 2002 Road King, our friend, Oscar, was ready for more power. He’d done the normal upgrades such as pipes and air cleaner, but now the 88ci mill just wasn’t putting down the horsepower and torque he desired. Over the 10 years Oscar has owned his King, Harley has continued to up the engine displacement of its OE models from 88 ci to 96 ci and now surpassing the century mark with the 103s found in the latest models.
Of course Oscar’s first thought was to upgrade to a brand-new Harley with more power, a better frame, and an extra gear for highway cruising. But then a new bike would mean new payments and that didn’t sit too well with him. So after weighing his options, he decided the easiest way to get more power would be to bump up his displacement with a big-bore kit from S&S. Just by swapping out the stock cylinders and pistons for a set of 3.972-inch bore cylinders and pistons, he could nearly hit the triple-digit displacement mark, arriving at 97ci. Going this route would be a relatively easy bolt-on affair and wouldn’t require splitting and boring the crankcases.
Once the bike was at his local dealership, Los Angeles Harley-Davidson of Anaheim, and the top-end was torn down, the service tech, Kevin, noticed a problem. After nearly 60,000 miles, Oscar’s flywheels had taken a turn for the worse and had shifted and come out of true. As he cycled the flywheel assembly, Kevin noticed that they were beginning to bind up. Fortunately the issue hadn’t gotten too severe yet and hadn’t caused any internal damage, or worse, left Oscar stranded on the side of the road somewhere.
At this point, Oscar considered just having the dealership pack the engine up and ship it to Harley to go through the company’s remanufacturing program. While this would result in a factory-fresh engine, it wouldn’t solve his need for more power; he’d still be sitting at the original 88ci displacement and relative performance the bike came with. Not sure where to go next, Oscar hit us up for advice, and in turn we went straight to the source and asked S&S its opinion.
After some investigating and discussing Oscar’s dilemma with his collogues, S&S Marketing Manager Bruce Tessmer came back with a solution: ditch the stock flywheel assembly and shove one of S&S’s 4-3/8-inch stroke flywheels in between the cases. With the same stroke as that found in Harley’s late-model 96ci and 103ci bikes, S&S stated that its 4-3/8-inch flywheel would fit into the Oscar’s 2002 crankcase. Best of all, the flywheel assembly would squeeze in without having to machine the crankcases—like the big bore kit, it would essentially be a pressed-in/bolt-in affair. The combination of the big bore kit and the stroker flywheel would put the bike’s displacement to 106ci, past Harley’s late model OEs displacement. To help squeeze even more power out of the big-bore/stroker setup, S&S recommended adding a set of its 585 Easy Start cams, 58mm Single Bore Throttle Body kit, 58mm manifold, and one of its new Stealth/AirStream Air Cleaner kits. Oscar took the advice and added to his order some S&S Quickee Pushrods and tubes and hydraulic tappets. To dial everything in and make sure the bike stays in tune, he also got one of Dynojet’s new Power Vision EFI modules. The combination of all these components and the huge jump in displacement should result in some great horsepower and torque numbers, but more importantly for Oscar, the end result will be like riding a completely new and exciting bike.
This is a pretty involved hop-up so we are going to break it up into a couple articles over the next few issues. Follow along as we show you some of the main components from S&S that will be used to rebuild this engine.