Harley-Davidson is not reinventing the wheel with the Milwaukee Eight engine. They’re just trying to make the wheel roll a little smoother.
There’s hardly been any larger a raucous caused by a motorcycle manufacturer this year than Harley-Davidson’s with the new Milwaukee Eight engine. The ninth in the company’s history, the Milwaukee Eight engine’s coup de grace is the new four-valve cylinder head and reversion to a single cam set valve train, versus the two valve head and twin-cam set up as per usual.
The hate has flowed thick and fast. Most of the comments I’ve read have centered on the fact that this technology has been around as long as the internal-combustion engine itself, and that Harley has no right to jump up and down about something which is commonplace in thousands of other motorcycles you and I can buy.
But here’s the thing: they can and should jump up and down, and here’s why
Harley-Davidson is as old-school a company as you can possibly get. It prides itself on its heritage, a history that’s been earned through good times and bad, and it never loses sight of what its customers actually want—which is big American V-twins built for cruisin’. These are the engines the company build and these are the bikes the company build. Once the Internet haters out there get this thought in their heads, they’ll realize just how big a deal this engine actually is.
H-D has a sound, a feel that plenty of other companies have tried to replicate and can’t, and keeping the masses happy, as well as attracting new ones, has become company policy number one for the Milwaukee faithful. The Milwaukee Eight engine, gifted to the entire Touring lineup of Harley-Davidsons, is thus the culmination of years of research, chatting to Harley and non-Harley riders alike, finding out what they want from a new Big Twin.
Basically, it boiled down to four key points: keep the noise, keep the feel, increase the torque, reduce the heat. Riders wanted a real Harley Big Twin. That means the rumble—but not too much rumble. Vibration was a big issue with the new engine designer Alex Bozmoski had to deal with. “Our core customers were saying ‘don’t touch it, it’s part of the brand!’ but others that wanted to buy into the brand thought the vibrations were too much,” Bozmoski said of the old twin-cam engine. “With the Milwaukee Eight, we started experimenting with a balancer and eventually we got it to about 75 percent of the previous engine’s vibration, and that made both groups pretty happy.”
Reducing the valve train noise meant it also freed up a few decibels in the exhaust, which was music to the ears of potential H-D owners and still got Harley under the EPA’s noise-meter test limits.
The move to the single cam heads meant much of the valve train clatter from the previous Touring engines has been reduced, with idle now reduced to a thumping low 850 rpm. This deals largely with another problem—heat. Lower revs mean less heat, with that heat dissipation helped by a new exhaust system and is another area Bozmoski’s brain bashed away at for the years of Milwaukee Eight development.
“We’ve reduced the heat with the pipes,” Bozmoski starts, “but it really comes down to the engine control. The precision cooling of the engine is allowing us to have this really high-functional, four-valve cylinder head. It allows us to run as far advanced as possible so we’re not creating heat by returning the spark to keep ourselves away from detonation. To do that we put individual cylinder knock sensors in, and the throttle body now stands at 55mm versus the 50mm of the old engine. So now our exhaust gas temps are much lower (around 100 degrees lower), the pipes are a lower temperature, the heads are a lower temperature and the overall ride is cooler.”
The four-valve head means there’s 50 percent more intake and exhaust flow capacity and with the use of hydraulic lifters, valve adjustments are a thing of the past, according to Bozmoski. There’s also no left-right adjustment on the intake or exhaust.
“Putting the adjustment in caused us to have more adjustments,” said Bozmoski. “We were faced with either having to design this really advanced adjustment system or we were going to do something very different. What we ended up doing was having this factory set. So right now you don’t have to adjust left-to-right for the life of the motor.”
The clutch and gearbox have also come under the microscope. New for this engine is the Assist and Slip clutch that Bozmoski claims reduces the lever pull effort by about seven percent, and the gearbox now has a spring-loaded first gear that takes care of excessive noise, especially when the engine is warm.
Bozmoski is so confident of the design, he says Harley-Davidson has done over 1.5 million miles of accelerated testing and 7000 hours of running without the valves needing to be touched.
In all, there are three new engines in the Milwaukee Eight lineup—the former 103 grew to a 107 with a 99.9mm x 111.1mm bore and stroke; the 110 was hiked up to a 114 via a 101.6mm x 114.3mm B&S, and with the Screamin’ Eagle engine kit, the 114 can be made into a 117 via a new big-bore cylinder package.
Interestingly, despite having about 30 pounds of overall weight in larger components added to the engine, Harley-Davidson claims the weight gain is close to neutral overall, thanks to the much tighter packaging of the engine.
Another advancement for Harley has been the introduction of new suspension for the Touring lineup. The new suspension’s preload can now be adjusted to match the load of rider, passenger and gear without tools or an air pump, with marked lines on the adjuster knob to let you know the right setting for a given ride condition.
The chance to sample this brand new chunk of Milwaukee muscle came in Tacoma, Washington, on a dreary and wet Tuesday morning. It would mean the majority of our ride was either soaking or just slightly drying, giving a perfect demonstration of the low-speed manners of this new beast. For this test, I focused mainly on the Road Glide Ultra Limited and had a quick scoot on a Street Glide with the Screamin’ Eagle 117 kit fitted.
The first thing you notice when firing up a Milwaukee Eight engine is the drastically reduced vibrations at idle and the speed at which the revs rise and fall. The new motor’s lack of vibration is pretty astounding, giving (almost) a Japanese twin feel at the twist grip. It still retains that H-D personality, with the right amount of thump dialed in as Bozmoski describes, but compared to the 103 of last year it’s an astounding difference.
The second thing that springs into mind is the first gear. We’re all familiar with the traditional Harley ‘clunk’ when selecting first gear from neutral, right? This is all but eradicated on the Milwaukee Eight, delivering an even bigger surprise to me than the initial feel of the engine.
The Milwaukee Eight’s throttle response is also improved over the former 103c.i engine. Bosmoski noted that one area Harley couldn’t sacrifice was the engine’s slow speed manners due to the amount of bikes that are used in parades, so navigating the drenched Tacoma roads in peak hour traffic showed his team had got this pretty spot on. There’s not the jolt from a closed throttle you used to get with the former engine, instead the drive is nicely metered when transferring the extra torque to the ground.
Harley-Davidson claims the new “Milwaukee-Eight 107 accelerates 11-percent quicker 0-60 mph, equal to a two-to-three bike-length improvement, and 11-percent quicker from 60-80 mph in top gear, equal to a one-to-two bike-length improvement, compared to the Twin Cam High Output 103.” I can’t comment on the overall acceleration improvements because A) the road was soaking wet and B) because saying “one-to-two bike length” as a form of exact measurement is completely inaccurate and therefore pointless. Why not just quote quarter-mile times?
What I can say is by the seat of the pants, the engine does have more pep from the moment you crack the throttle and up through the midrange. Top end was not ventured into due to road conditions, so I won’t comment on that.
On the Road Glide, the biggest improvement was not so much the extra torque, but the lack of vibration. The reduced vibes and nicer throttle response made the ride so much smoother, and the extra torque meant I would often ride a gear higher than I would normally use and just ride the torque, rather than shift. The new motor pulls smoothly from exceptionally low revs, and the ride is now a bit more relaxed than the 103 c.i. motor. More muscle means less effort to do the same job.
I jumped on the Street Glide for a run on the COV 114 engine and it has just that little bit more of everything, more power, more torque and a similar nice throttle application. Again, you can let the motor run exceptionally low in the revs in a gear higher than you’d expect and it’ll pull you out, no problem. This would be my pick of the two purely because it felt easier to manage than the 110. It’s not an enormous difference, but having that extra torque was a good feeling, especially on the wet roads we encountered on this trip.
Harley’s new motor may not be what many would consider technologically advanced, but it sure feels it. The new single-cam motor feels more refined in every detail to the former lump, while retaining all the sounds and feels that define the brand.
As one of only nine motors in its history, it’ll probably be a long time before we see a new one, so Harley needed to get this one right. Good news is, they did.