Darn near twice the horsepower and torque in a day, without taking the engine out of the frame. No complicated or expensive machine work required, all done with wrenches. Sounds good? That’s a 96 or 103 Harley putting out 110-plus hp with a torque number to match or with a few quick parts substitutions bumping those numbers up into the 125 ranges, torque, and horsepower. That’s power and performance that’ll get your attention, the kind of oomph that’ll have a bagger bike towing the motor home and not the other way around. Almost.
For a while now we’ve been listening as the guys at Speed’s Performance Plus repeatedly told us all the boosts and benefits of big-bore cylinders, cam swaps with a gear drive, and big-port/high-flow heads. Well, at this past Biketoberfest in Daytona we got to see up close and personal the results of all this, all at once. “It our complete 106 kit,” Jamie Hanson said. “We’re doing one right now. Want to stick around for awhile? I think you’ll like the results.” An invitation hard to refuse.
The package the SPP guys have come up with, and something Jamie uses on his own bike and has refined to perfection, is an easily installed complete top-end swap, able to be completed in a day. And the result, he quickly points out, is a big-power motor that can be ridden anywhere, anytime. No hard starting, no hot running, no problems at all. Just horsepower and torque galore. It all begins with a pair of S&S 106-inch cylinders with the matching forged pistons and rings, bringing the bore size from the stock 3.750 inches to 3.927 inches.
a pair of S&S 106-inch cylinders with the matching forged pistons and rings, bringing the bore size from the stock 3.750 inches to 3.927 inches.
No case-boring or crank rebalancing required. “Those flat-top pistons usually put the bike at about a 10.6:1 compression ratio,” Jamie says. That’s tight enough to produce a big bang but not so high as to cause starting or running woes. It’s a setup perfectly compatible with ordinary pump gas. That’s matched with a gear-driven 635 cam set, the S&S Easy Start versions further increasing the everyday friendliness, and SPP installs them using one of their own super-strong billet cam plates. Depending on the bike and the condition of the original lifters they’ll drop in a set the S&S performance rollers too. All this is then topped off by a pair of S&S Super Stock 79cc cylinder heads. Compatible with the stock Harley-Davidson rocker boxes (more of that no-machine-work/all-bolt-on approach) and coming with 1.940-inch intake and 1.575-inch exhaust valves, 0.640-inch lift springs and reconfigured high-flow ports those heads are an economical performance upgrade and a big step in the right direction. And that’s it—at least as far as the major parts go. Now, on a 103-inch engine the gain of just 3ci might not seem worth the effort or expense of new cylinders, but, remember, this setup is a coordinated package and is about more than just displacement.
“The cool thing about it all,” Jamie says, “is that it’s something we can do right at an event, like right now. And with that comfortable 10.6 compression ratio and the Easy Start cams we know it’s going to be everyday friendly on pump gas, ready to go anywhere in the country, anytime.” An option, he tells us, is to use a thinner 0.030-inch head gasket and bump the compression up to 10.8 for a little bit more bang. Jamie did this on his own bike, also stepping up to the next level of performance heads with the R&R Stage III Torque Ports. He switched to a marginally bigger 58mm throttle body too. The result? He came away with 123 hp and 130 foot-pounds torque.
He came away with 123 hp and 130 foot-pounds torque.
In either case, 110 to 115 hp with the standard package or going big like Jamie did, with power like this a beefed-up clutch, is a must, and Speed’s includes it in the package. They’ll install a Speed’s Clutch Pack with an extra friction plate and an extra drive along with a stronger-tension diaphragm spring, 10-percent stiffer than stock. One of those trick Speed’s lifetime oil filters/oil coolers is included too. Anytime you bump up performance like this you’re creating more heat, and that finned filter/cooler helps dissipate it.
Anytime you bump up performance like this you’re creating more heat, and that finned filter/cooler helps dissipate it.
And of course the job winds up with a Power Commander and a custom dyno tune, a performance map written specifically for this engine.
Talk about a jump in performance. Stock 96-inch engines average 62 or 63 hp, maybe 68 from an original-spec 103. Contrast that with what’s on hand after that 106 kit joins the party. And as we saw in Daytona it can happen in a matter of hours. Next time the Speed’s Performance crew is at an event in your area (the schedule’s on the website) stop by and take a look for yourself.
Source: Speed’s Performance Plus speedsperformanceplus.com (605) 695-1401 — MN (605) 695-2272 — SD