HARD to believe, but it will soon be some 20 years since Harley-Davidson started to replace the Evo engine with the Twin Cam. Indeed it is already 31 years since the 1984 debut of the powertrain that is widely regarded as turning Harley around after the 1981 management buy-out from AMF and subsequent near-death experience.
Though not a revolution in technology terms as such, the Evo did feature much new thinking relative to its predecessors. Initiatives such as the improved cooling and elimination of temperature differentials by using all aluminum rather than aluminum mated to cast iron construction; then there were the revolutionary customer-friendly initiatives such as being oil-tight, reliable and durable.
My, how the purists howled - for as long as it took to get an order placed at their nearest dealership!
Initially the company was only making some 30,000 or so of the Big Twin Evo configuration; indeed the company's entire output was only around 36,000 bikes in 1986, but by the time Harley closed down production of the Evo, estimates suggest that some 1.4m 1,340cc/82 cu in Evos had been made, plus the 883/1200cc unit construction Sportster variants.
Indeed, in addition to saving Harley-Davidson, the Evo is also credited with taking customizing in an altogether new direction, fuelling the ground-up build boom of the 1990’s, with the wait-list inspired closure of the factory crate motor program in the mid-1990’s handing the momentum that Harley had built to the aftermarket on a plate.
Not surprisingly it was right around that time that S&S Cycle themselves went in the opposite direction, bringing together packaged component offers into a single part number complete engine order opportunity for the first time. The rest, as they say, is history.
The abiding characteristic of the Evo, the one big factor that was truly revolutionary in Harley engine terms, was its durability. Evo engines could do tens of thousands of miles, hundreds of thousands of miles even, in a way that prior Harley power plants simply couldn't.
In the wake of all those miles there emerged a stock replacement and performance upgrade component aftermarket the like of which had also never been seen before - with S&S Cycle leading that market. Fast forward to 2015, and there are still thousands, probably hundreds of thousands of Evo engines still doing the miles, no doubt repeatedly 'breathed on' since they came out of the factory gates, and no doubt many of them 'breathed on' by S&S dealers and their customers.
Having paid homage to what the Evo did for us, time perhaps to remind ourselves what we can do for the Evo. Here we present a round-up of some of the components and performance upgrade packages that S&S Cycle still has as active SKUs, 31 years after that fateful launch.
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| "Boost performance without having to split the crankcases" say S&S about these kits. For 1984 - 1999 carbureted engines, installation is "as easy as a stock top-end rebuild" with no flywheel rebalancing required. The kit delivers 80 cu in at 10.2:1 compression ratio. The kit includes cylinder heads, a Super Stock cylinder head kit with valves and springs installed, manifold with o-rings and flanges, all the required hardware, top end gaskets, a 561 S&S cam, adjustable chromoly pushrods, an HL2T spacer kit to limit the range of travel of the hydraulic tappet plunger, a Super E carb kit - just add the required oversize pistons, or order with mated and fitted pistons; available natural or Wrinkle Black powder coat finish |
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S&S has been making stock bore stroker kits since the early 1960s. The excellent power gains for the money and ease of installation mean they are still popular. Stock bore strokers reuse the stock cylinders, heads and crankcase, which helps make them economical, and since they don't require crankcase modifications, they are easy and economical to install. For maximum performance S&S recommends their 89" Stroker Hot Set Up kit which includes an S&S camshaft, carb, pushrods and S&S cyclinder heads. They fit 1984 - 1999 carbureted and 1995 - 1998 EFI engines, can be configured to order (CTO), and S&S report "significant" increases in horsepower and torque |
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| Available from 88" out to 103" displacements, S&S 3-5/8" big bore/stroker kits are available for 1984 - 1999 carbureted and 1995 - 1998 EFI engines. S&S say they offer a significant increase in horsepower and torque and include cams, tappets, valve springs, rocker arms, rocker covers, manifolds, carburetors, EFI throttle bodies and EFI modules. The kits can be configured to order (CTO) and are available natural or Wrinkle Black powder coat finish |
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| Built around their most popular 3-5/8" bore Sidewinder, these kits include a 585 camshaft, carb, pushrods, and all required hardware and gaskets in addition to the standard 4-5/8" flywheel assembly, 3-5/8" cylinder and piston kit, .640" valve springs, adjustable chromoly pushrods, an HL2T spacer kit and a Super E carb. Described as an economical route to a large displacement engine, performance can be further enhanced by the addition of Super Stock cylinder heads, but the kits can also be configured without heads if S&S performance replacement or stock heads are to be used |
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| For those who want to "go the whole hog", S&S V124s for stock Evo carbureted, fuel injected or custom Evo style frames feature their recently introduced press together 1.671" diameter crankpin/.927" wristpin 3-piece flywheel assemblies with the long piston stroke and high performance gear driven cam resulting in large horsepower increases over the stock engine. Available in natural or Wrinkle Black powder coat finish, the Super G carb has a signature S&S teardrop slotted "Slasher" air cleaner cover, 640 camshaft, S&S forged pistons (and piston cooling jets), 10.8:1 compression ratio, 4-1/8" bore by 4-5/8" stroke, large fin pack on the heads and cylinders, high-volume/high-pressure oil pump and electric compression release for easy starting under any circumstances. Options include Intelligent Spark Technology (IST) or Super Stock ignition system on carbureted engines. For fuel injection engines, single bore EFI throttle body with S&S Classic Teardrop air cleaner, Magneti Marelli style S&S Variable Fuel Injection (VFI) module with built-in three stage engine overheat protection, closed loop fuel system, dual oxygen sensors provide air-fuel ratio feedback for correct fuel delivery under any condition and S&S ProTune II software provides base fuel maps for most aftermarket exhaust systems |
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| Available for '84 - ’99 carbureted chassis and custom Evo-style frames, the shorter than stock height makes for easy installation. Short stroke is said to produce less vibration and longer engine life, with piston cooling jets, large cooling fins, High Volume High Pressure oil pump, S&S 585 cam and lightweight single coil valve springs to minimize valve train noise, S&S forged rocker arms, chrome plated rocker covers, tappet guides, and gear cover and Super E carb. The V111 features the recently introduced press together 1.671" diameter crank pin and .927" wrist pin 3-piece flywheel assembly. Options include natural, Wrinkle Black powder coat or polished finish and Super Stock ignition |
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