S&S 640GE Gear Drive Easy Start Cams greatly improves valve timing accuracy by eliminating timing chain lash and allow stock starter to start any engine. The 640 cam is designed for engines of 95 inch or more with compression ratios between 10.5:1 and 11.5:1 used in S&S 124 inch engines.
Cam set includes inner gears and fits 1999-2006 Harley-Davidson® big twin (except '06 HD® Dyna®).
Note: These cams are not bolt in and will need special valve springs.
Pinion shaft run-out must be checked before installing S&S® gear drive cams.
A hydraulic press and other professional tools are required to install S&S gear drive cams. Additionally, material must be removed from the inner surface of the stock
gearcover. The stock crankcase will require clearancing for S&S .625", .640", and .675" lift cams. S&S recommends that gear drive cams be installed by a professional
New cam bearings and a new gearcover gasket are required to complete cam installation. Gear drive cams for 1999-' 06 models require the use of ball bearing style cam
bearing rather than the stock roller bearing. Roller bearings have more internal clearance which can cause excessive gear lash and increased noise. The correct parts are
provided in S&S Camshaft Installation Kit, part #106-5896.
Due to the inherent characteristics of gear drives, you may experience more valve train noise with gear driven cams. Oversized and undersized gears are available to help
achieve correct gear lash. We have found that with 160 lb. of valve seat force, the S&S gear drive cams will perform well up to 6200 rpm. If higher rpm is anticipated,
valve springs that provide higher seat force should be used.
S&S can do a special order cam. Contact your S&S Customer Service Representative for more information.
Not legal for sale or use on CA or EPA pollution controlled motorcycles.