What a 107" Twin Cam build makes
Simulated rear‑wheel horsepower and torque — measured after the primary drive, clutch and transmission, the same way a chassis dyno reads a bike. These are not flywheel numbers, and they are not directly comparable to a manufacturer’s crank rating. Rev ceiling for this combination: 5900 rpm, limited by cam.
A 107 is a 96 or 103 taken out to a 3.937" bore. It is the most common step up that still uses the stock crank and cases.
The extra displacement shows up as torque everywhere, not just at the peak, which is what makes this size popular on bikes that carry weight. The cam here is a step past the 100 hp build and takes the useful range with it.
Note what sets the rev ceiling on this page and compare it with the 117. Once displacement and head flow stop being the limit, the camshaft and the valvetrain are what decide where the pull ends.
The build
| Engine | TC107 big bore (96/103 + 3.937) |
|---|---|
| Crank / balancer | A motor — non-balanced (Dyna / Touring / CVO) |
| Pistons | Forged flat-top (11cc combustion gain) |
| Head gasket | Cometic .030" — neutral baseline |
| Cylinder heads | STOCK -06 + S&S CNC port service · 1.9/1.575 |
| Porting | Stage 2 CNC port (full) |
| Camshaft | S&S 570 · 240/255 dur · 0.570" lift |
| Valve springs | S&S 106-5909 Sidewinder — .650" max lift — 7mm stem, Twin Cam 2005-2018 |
| Rocker arms | Stock rocker arms — 1.625:1 |
| Pushrods | Stock pushrods |
| Lifters | Short-travel hydraulic (Feuling/Andrews) |
| Induction | HPI / SE 55mm throttle body |
| Exhaust | 2-into-1 stepped (D&D FatCat / E-Series) |
| Air cleaner | Screamin' Eagle / Stage I high-flow |
| Tune | Dyno-tuned (matched to build) |
| Power adder | None (naturally aspirated) |