Today, Harley-Davidson launched its new Pan America and Pan America Special adventure bikes with much hoopla. There’s lots of tech packed into the new machines (leaning ABS/traction control, electro-suspension, etc.), but the engine itself could be the most interesting feature.
The new Revolution Max 1250 is Harley-Davidson’s most powerful engine available in an off-the-shelf bike, ever. The Harley-Davidson Screamin’ Eagle 131 Crate Engine, released with much ballyhoo last year, only made 121 hp. The new 1250 is supposed to make 150 hp, and 94 lb-ft of torque. Those are basically sci-fi numbers for old-school Harley-Davidson owners—still behind the latest Multistrada V4, for sure, but a lot more than even the latest Milwaukee Eight 117. And the bike, while not a Skinny Minnie Miller, comes in at 499 pounds dry weight for the base model. So how/why did the MoCo do it?
Old-school Harley-Davidson engines use old-school materials and designs. “Ironhead” doesn’t exactly scream 21st century. More recent engines have gotten with the times, sort of; Harley-Davidson has liquid-cooling at the top of its lineup (the Touring series) and the bottom (the Street series).
The Revolution Max 1250 engine (a 60-degree V-twin) takes things much further. Along with liquid cooling, the engine also has a computer-controlled variable valve timing system (VVT) on both the intake and exhaust camshafts. Other manufacturers (BMW, Ducati) have variable valve timing, but only on the most expensive, advanced bikes, so Harley-Davidson is exploring new territory here.
According to H-D’s presser, the VVT system “advances or retards exhaust and intake camshaft timing independently through a potential range of 40 degrees of crankshaft rotation.” You know how motojournos always say an engine is “tuned for torque” or “tuned for horsepower”? Well, this allows Harley-Davidson to tune for both. The presser says “VVT broadens the overall powerband and improves torque management and efficiency compared to the same engine with fixed valve timing. This allows the same engine to provide both low-end grunt for acceleration off the line as well as the thrill of high-RPM horsepower.” Harley-Davidson also says it can improve fuel mileage.
The engine itself uses single-piece aluminum cylinders, forged aluminum pistons, and magnesium rocker covers, cam covers and primary cover. Not exactly mind-blowing technology, but you need to make these steps to improve performance or reduce weight, or both. The heads are aluminum as well; because the heads are a key mounting section of the chassis, Harley-Davidson used targeted heat treating to make them flexible at the mounting point, but rigid over the combustion chamber.
Somewhat amusingly, the H-D press release has to spell some pretty obvious stuff out. Either they’re planning on dealing with air-cooled MoCo diehards, who don’t understand why you’d want a radiator on a bike, or maybe clueless influencers who’ve never had an air-cooled bike overheat. Or maybe it’s for sloppy online journos, who can’t be trusted to get the details right … errrr, the point here is, liquid cooling allows for tighter tolerances, eliminates overheating, and even cools the engine oil. For the obstinate holdouts who still want a V-twin that sounds like a tractor, H-D says “Desirable engine sounds – a stirring exhaust tone – can predominate because noise from internal engine sources is reduced by liquid cooling.” Take that, you jaded Harley dealers who just want to go back to the Twin Cam 88!
Looking at the engine, it’s unclear if it will “crash well,” an important feature of any adventure bike powerplant. However, Harley-Davidson does seem to have paid at least minimal attention to such realities, with notes like “A coolant drain plug is recessed and guarded by a foot peg to limit vulnerability to damage in off-road riding situations.” Harley-Davidson did go to some effort to hide the whole cooling system, too, although it looks like there’s room for improvement on the electrics placement.
Going into the engine’s internals, there’s a set of 30-degree-offset offset connecting rod journals. This creates a 90-degree firing order, and Harley-Davidson says this allows improved traction in some offroad situations, as well as smoother delivery. The pistons are forged aluminum, with a low-friction coating on the skirt and low-tension rings to also reduce friction. Low-internal-inertia engines are the name of the game these days, and H-D is keen to play. Note that the 13:1 compression ratio sounds high, and Harley-Davidson says the engine needs high-octane fuel to make max power. But, it will run on lower-octane gas if needed, thanks to anti-knock technology. This should spare you from an awkward piston meltdown when you get crappy fuel on the Alcan Highway.
As you’d expect, Harley-Davidson used hydraulic valve lash adjusters, so you won’t have to tweak the tappets every 10,000 miles. The 1250 has roller-finger valve actuation; the valves and valve actuators are in constant contact as the engine’s heat changes, which reduces valve train noise and puts consistent pressure on the valve stem. In turn, that “facilitates more-aggressive camshaft profiles which can boost performance.” That’s a white-collar way of saying mo’ powah!
There’s more. The exhaust valves are sodium-filled to dissipate heat. The MoCo uses a “complex casting technique” to put suspended oil passages in the heads, improving cooling and reducing weight. a semi-dry transmission, to reduce oil drag that causes power loss. Dual spark heads, with “dual side strap” spark plugs, for higher combustion temperatures. A trick airbox that allows tuned velocity stacks over the throttle bodies. The press release goes on and on. Not all of it is earth-shattering stuff, but it’s smart, and it shows Harley-Davidson actually tried to engineer this thing correctly.
That doesn’t mean the company’s succeeded; I haven’t ridden the bike, and it hasn’t gone through a generation of usage on-road or off, the ultimate test. I won’t tell you this is a perfect engine. However, it’s a sign of a mindset shift at the Motor Company.
Why did Harley-Davidson go to all this effort, when it hasn’t before? Two simple reasons: The rules, and the customers, are changing.
There’s no need to go on ad nauseum about Harley-Davidson’s dying customer base. It’s simple: Rich boomers used to buy Harley-Davidsons, and now they don’t, and there aren’t enough rich hipsters to make up the difference. So, Harley-Davidson has to find customers elsewhere, and that means building bikes around better tech.
The changing rulebook is another matter entirely. The variable valve timing tech is a clever way to keep on building big twin-cylinder engines, just like Ducati and BMW, while meeting emissions requirements. Note that H-D even worked to cut down mechanical noise with this new engine. All these things matter in the brave new world of Euro5 and beyond.
It’s a peek at the future of Harley-Davidson, really. In its presentation, Harley-Davidson confirmed its 1250 Custom cruiser, built around this same engine, is still in the works. Don’t be surprised if the 1250 and similar VVT-equipped models are the core of Harley’s Euro lineup within a couple of years.
And sure, that variable valve timing is good for emission and allows more horsepower, but it also allows a lot of low-end torque as well. Looks like Harley-Davidson might have built an engine that appeases all the faithful after all.
For more details, and a chance to see Jason Momoa wearing a pair of pants that he apparently stole from a chain gang, watch Harley-Davidson’s official launch video below: