S&S, 640G (IOG) gear-driven camshaft kit

.640" valve lift. IOG = gear driven camshafts, with internal and external drive gears. Complete kit with installation fasteners, bearings and gasket.
For 95" and up models with a compression ratio of 10.5:1 to 11.5:1 (standard on S&S 124" engines).
The gear drive system is, in fact, a revolutionary, different and far more reliable construction. Especially in high lift/performance applications, compared to the OEM chain drive design. A gear-driven camshaft is stronger and will suffer none of the mechanical problems associated with OEM chain-driven camshafts. The S&S gear drive kit will increase valve timing accuracy and therefore power, by eliminating timing chain slack and the loose fit of stock cam gears. The only downside of gear drive is that you may experience a slight increase in mechanical noise; which is why the OEM uses a chain. It has no other mechanical advantage. Since the chain guides and tensioner are removed, there is no longer any chance of these parts failing and damaging other parts of the engine. The S&S gear drive kit reverses the rotation direction of the rear camshaft, providing additional operating clearance between the cams. As a result, higher cam lifts are possible with the S&S gear-driven cams.
Note: With the exception of the 475G and 510G camshafts, adjustable pushrods (such as MCS 503573) are required to compensate for the smaller base circle of the camshaft of these cams.
Note: It may be necessary to remove material from the inner surface of the OEM gearcase cover before installing the S&S external drive gears.
Note: The S&S installation kit required (503566) for the gear driven camshafts is included in this complete kit (IOG).
Note: Using camshafts with .625", .635", .640" and .675" lift will require crankcase grinding.
Note: OEM beehive valve springs on Dyna 04-17; Softail 04-17 and Touring 04-16 models support valve lifts of up to 0.590" and a valve seat load of 160 lb, up to 6200 RPM. Running above 6200 RPM or with lifts greater than 0.590" will require high-performance valve springs.


Specifications


Brand
S&S


Application
99-06 Twin Cam (Excl. 2006 Dyna) with stock non-hydraulic chain tensioners (NU)


Sales unit
Kit


Material
Steel


Packaging weight
2.77 kg


HS Code
84831021


Motorcycle family
DYNA, SOFTAIL, TOURING


Original name
S&S, gear drive 640G camshaft kit (IOG)