Speed’s Spotlight: Milwaukee-Eight Cam Swapping

Speed's Performance Plus on upgrading Harley-Davidson's latest Big Twin

That new Milwaukee-Eight sure got popular fast.” That’s what Jamie Hanson at Speed’s Performance Plus has noticed. The lineup of riders rolling up to the SPP mobile shop with those new-for-2017 engines has been impressive. And of course everyone has the same request.

As powerful and torquey as that OE multi-valve motor is, Harley riders being Harley riders, they want more. “And at first there wasn’t a whole lot we could offer,” Jamie says. A performance dyno-tune was an obvious first step, a custom map to replace the factory’s conservative engine-management plan. That’s always a big help. Slip-on mufflers and free-flowing air filters for the 107-inch version became available fairly quickly too (the CVO 114 already had an open, forward-facing air intake). But that was pretty much it.

“And those few changes made noticeable improvements,” Jamie explains. Plenty of those riders took full advantage of the Dynojet Tune License Program Speed’s offers too. A custom tune without the expense of the Power Vision unit itself is a sweet deal. “That License Program has gotten popular with everyone,” Jamie adds. “It isn’t just for the Milwaukee-Eight.”

But back to those Milwaukee-Eights and that lineup of riders. It didn’t take the aftermarket long to begin offering more than just slip-ons and air filters for that newest Harley engine, and just as quickly the techs at Speed’s Performance began incorporating it all into their bag of tricks. So along with performance mufflers, performance head pipes are now available to go with them, completing a full-flowing true dual setup. There are now full 2-into-1 systems for the M-8 baggers as well. And more to the point here, the aftermarket’s attention has also turned to that new motor’s internals. There’s a nice selection of camshafts and full cam kits now. “And we’ve already done a handful of these Milwaukee-Eight cam swaps,” Jamie says. The results have been eye-opening.

“We’ve already done a handful of these Milwaukee-Eight cam swaps. The results have been eye-opening.”

A little background to put things in perspective: Stock bikes—with the exception of some of new slip-ons and free-flow air filters—with the standard 107-inch M-8 engine routinely show horsepower in the 74 to 78 range on the SPP dyno. Torque is generally 95 to 97 pound-feet. Not a bad start. But now “start” can include more of that newly available hardware, specifically the performance cams. One of the recent jobs, completed at the past Sturgis event on a 114-inch CVO Milwaukee-Eight, tells the tale. And it’s a happy one.

“That particular bike already had performance slip-ons in place,” Jamie says, and with its stock CVO air filter, the addition of new head pipes and a License Tune it now pulled 85 hp and right around 117 pound-feet of torque. Impressive numbers on a basically stock engine, especially that torque number. Naturally, the owner wanted more.

Back up on the work table, the guys broke out the wrenches for a camshaft swap, and with this particular bike they stayed with the chain drive and used a .475-lift cam. Retuned with its new camshaft, the bike then delivered 107 hp and torque went up to 123 pound-feet of torque. Compare that before and after, pre-cam swap and after. Now, this particular cam was a T-Man grind, but that’s by no means the only option out there now. Some of the other M-8 possibilities are the 465, 475, and 550s from S&S, all available in choices of chain or gear drive (the first two are straight bolt-ins; the 550 requires new valve springs), and there’s an equally wide assortment from Feuling Parts, with Feuling also offering new cam plates, high-volume oil pumps, and more. And that’s just part of the list. The point being, Milwaukee-Eight cams and cam kits are out there, and with eight valves to play with they work.

And consider this. “We’ve had a Screamin’ Eagle Stage III Milwaukee-Eight on the dyno too,” Jamie says. That’s Harley-Davidson’s hopped-up 114 with special heads, higher compression, and a 2-into-1 exhaust. That bike pulled 109 hp and 125 pound-feet of torque. “Compare that with what we just got with the bolt-in 475 cam,” Jamie mentions. “The numbers, and overall performance, is right there.”
Got an M-8? Lucky you, you’ve got a heck of a motor there. But if you want more—and who doesn’t?—it’s there. The guys at Speed’s Performance Plus can tell you all about it.


Speed Performance Plus
605-695-1401 – MN
605-695-2272 – SD