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S&S Cams for 103"

Camshafts for 103"


S&S has developed two bolt-in cams for an otherwise stock Harley-Davidson® Twin Cam 103™ engine. Choose the cam that best fits your riding style. Available with S&S’ rock solid gear drive or for the economical stock chain drive, and in either Easy Start or standard configurations.

551 Torque Cam:

Ol’ Reliable! Still our best bolt-in bagger cam for 96 to 106 CID engines with 9:1 to 9.9:1 compression. Greatly improves low-end and midrange torque, strongest from idle-4000rpm. Bolt-in torque.

MR103 Midrange Cam:

These bolt-in cams are for the rider who wants more of everything without giving up low-end torque for high rpm horsepower, or vice versa. More power all across the wide power band, from idle to red line.

HP103 Horsepower Cam:

For the rider who really wants the most top-end horsepower. Easily make 100 horses from a stock engine with S&S intake and exhaust. Ideal for lighter bikes and racing applications where getting the most horsepower from a stock engine is imperative.

More Power! with S&S High Lift Camshafts

Open your valves higher and let more air into your engine. S&S high lift valve springs are required for the
S&S 635 H. O. cams.

The S&S exclusive Easy Start cams feature a built-in centrifugal compression release to make starting your big inch engine easy. For the full story, click here:

635 H.O. Horsepower Cam:

This is the cam set for the rider looking for maximum horsepower. With .635" lift, your engine can really breath. They’ll work even better when you have your cylinder heads CNC ported in Step 4. High lift S&S valve springs are required.

The Dynojet® 250i chassis dynamometer shows how much power an S&S air cleaner, performance exhaust and cams can unleash in a stock 103” engine. The lower, black curves represent the stock engine for comparison. The red curves show the new MR103 cams, which produce great torque and horsepower across the rpm range. The blue curves show the new HP103 cams, which are designed specifically for top-end horsepower. Over a hundred horses out of an otherwise stock engine. Sweet!
For the real horsepower junkie. We CNC ported the cylinder heads on the 106" engine, added an S&S 58mm throttle body, installed the new S&S 635 cams, and switched to the S&S Super Sidewinder 2-1 exhaust system. The dyno shows an increase of 46.2 horsepower and 26.4 ft-lb of torque over stock.


Gear Drive Cams

Cam Name
Easy Start

Complete Kit
Cams with Inner Gears*
Complete Kit

Cams with Inner Gears*
551 106-5737 106-5736 106-4868 106-4870
MR103 330-0303 330-0302 n/a n/a
HP103 330-0354 330-0353 330-0350 330-0349
635HO 330-0339 330-0338 330-0335 330-0334
2006 Dyna® uses 2007-up style cams
*Installation kit not included but recommended


Chain Drive Cams

Cam Name
Easy Start
551 106-4947 106-4858
MR103 330-0299 n/a
HP103 330-0346 330-0343
635HO 330-0331 330-0328
2006 Dyna® uses 2007-up style cams


Cam Valve Timing   Valve Duration Valve Lift Lobe Center Line Valve Lift @ TDC
Intake Exhaust Intake Exhaust Intake Exhaust Intake Exhaust Intake Exhaust
MR103 13° 33° 50° 22° 226° 252° .585" .585" 100° 104° .097" .191"
HP103 20° 49° 45° 26° 249° 251° .575" .575" 102.7° 101.5° .199" .206"
635 H.O. 19.5° 43.5° 58.5° 37.5° 243° 276° .635" .635" 102° 100.5° .186" .284"