Howard Kelly at S&S said their Super Stock Hot Set Up Kit would get me going in the right direction, so we placed the order and got the parts in quickly. Included in the $2,815 kit were pistons, cylinders, Super Stock heads, and .585 gear-drive cams. Lifters, push rods, and assorted gaskets were also in the box. This set up would take the stock 88” Harley motor out to a more respectable 95” which is pretty much the minimum for good performance nowadays and a favorite displacement for many engine builders. I had always been a great fan of the S&S gear-drive cams, so I was eager to try the rest of the kit. While we had the engine apart, we sprayed the cylinders black, another effort to make the bike look a little older (not such a great effort after reading about the Twinpan engine in last month’s issue. That Twin Cam engine was much older looking than mine). Everything slipped into place as expected, and it was off to put about three hundred break-in miles on it before dyno testing. We are always careful with motors.

At first, things didn’t start off so well on the dyno. I had my FLSTS header pipes on the bike and the kit didn’t seem to like them much. Also, my cute little ‘60s-style, round air-cleaner cover was overly restrictive. We only got this 100-horsepower kit up to 88hp during our first try. So after some head scratching, we looked around the shop and found a two-into-one Thunderheader and we simply took the round outer cover off the air filter, leaving the element exposed. We should have gone to a larger air cleaner since the kit was designed to work with the familiar tear drop-shaped S&S one, but we didn’t have one handy. The horsepower numbers jumped up into the low-to-mid 90s on the second go around and I’m sure with more tuning we could have got the engine into the upper 90s. Overall, the kit clearly worked as advertised. It was as easy as doing a top-end job on a Twin Cam, it retained good balance and felt like a factory part going down the road.

If you check out the dyno results, you’ll find a fat 52% increase in torque at higher RPMs and a solid 27% increase in torque down low. Horsepower was up 55% with the S&S kit. The new Twin Cam Harley motor was designed to handle this extra power, so there should be no long-term problems. This is a great benefit of hopping up the later-model Harley-Davidsons, you don’t have to worry about fragility. S&S warranties their products for a year to the original owner, so you aren’t left out on your own if you have problems.

We learned three things during this project. One, which we knew but confirmed, was that 95” is a great displacement. With proper plumbing, upper 90’s in horsepower and torque are easily available, probably the full 100hp with carefully chosen parts and scrupulous tuning. This puts you up in the top 20% of hopped-up motors, only the 113’s, 120’s and 124’s will show you their hind ends, but you’ve none of their giant-motor worries. The second lesson learned, after experimenting with the two different exhausts and the air cleaner, was the importance of matching parts. I’m putting my FLSTS pipes and round air cleaner back on because that’s what I want, and I’ll give up 5 to 7hp and ft-lbs to keep the look I like. I also left the stock, quieter lifters on my bike. If you are simply after the power, however, you have to use the parts the kits were designed for. In this case, the S&S tear- drop air cleaner and a good two-into-one seemed to suit this engine better. And I’m sure the S&S lifters were probably better for sustained RPM running.

Finally, especially with fuel injection, some careful tuning of the bike needs to be done to get the hard parts to produce all the power of which they are capable. The kit can be installed in a garage, there was nothing complicated about it. But the tuning needs to be done by a skilled technician; you can count on an extra 5 to even 10hp and ft-lbs at the tuning stage. We’ll do a follow up article in the future and let you know how it compared to other hopped up bikes in our area. The stories always get back to us.