The Madness of Muscle: S&S Takes Harley’s Milwaukee Eight Engine To 136 ci

S&S is at it again, with a massive new big-bore kit they claim will hit 150 hp on a Milwaukee Eight engine. Credit: S&S

Harley-Davidson’s Milwaukee Eight engine is already a heavy hunk of muscle, with as much as 114 ci capacity. But if you think bigger is better, the aftermarket tuning wizards at S&S might have what you want—they’re now offering a big-bore kit that will take your MI8 engine to a whopping 136 ci and a massive horsepower boost as a result.

Converting to metric, that works out to roughly 2229 cc. It’s a big boost in displacement, and it requires more than just swapping out a set of jugs. According to S&S, achieving this growth requires you first buy their 4.32-inch-bore cylinders and pistons, which will fit the MI8 crankcase or the S&S MK-series crankcase. Then, you’ve got to install the 4 5/8-inch Stroker flywheel kit—presumably this is to manage the weight of those oversized components.

Put it all together, and you’ve got a big-bored MI8 engine that will still slot right into the original chassis, retaining the same height as the stock engine. S&S was even thoughtful enough to match the powdercoating on the new cylinders to H-D’s stock engine finish. Riders can opt for highlighted fins, or non-highlighted fins, or a Black Granite finish. You retain your engine’s original serial numbers, too.

Multi-layer steel gaskets are included, and a 136-inch cam cover badge, so all your friends know you’re cool.

Credit: S&S

How much power does the new top end make? That depends on other components (exhaust, EFI programming). S&S says “Huge displacement increase means huge power increase,” and shows a chart implying 150 hp is possible from this setup (see above). Find more details on the kit, including pricing options, at the S&S website here.


Join the conversation!