Easy Start Cams from S&S Cycle make hard starting obsolete for 1999-16 Twin Cams. Chain drive version Start any engine with a stock starter Save your starter and battery! Reliable - tested for 10,000 starts and didn't even run the battery down! Automatic - no buttons to push Camshafts that exceed the limits of the stock valve springs require the use of special high lift springs. Most S&S cams have higher lift than stock and are designed to take advantage of the extra flow of ported stock heads or S&S Super Stock heads. Due to the high lift of these cams, S&S adjustable pushrods are recommended. To get the best performance from a performance cam installation, a high flow intake and exhaust system is also recommended. Quick installation and Easy Start Cams allow stock starter to start any engine. Kit contains cams, gearcover gasket, cam bearings, and instructions. 1999-2004 stock springs will handle camshafts with lift up to 0.510". If a camshaft with higher lift is installed, high performance valve springs capable of handling a greater lift must be used. 2005-up stock valve springs will handle camshafts with lift up to 0.585". If a camshaft with higher lift is installed, high performance valve springs capable of handling a greater lift must be used. Cams with over 0.585" of lift will cause interference between the valve spring top collar and the valve seal with stock cylinder heads. Installation of S&S chain drive cams requires special tools. Attempting the cam change operation without these tools will be difficult. Damage can result which will not be covered under warranty. S&S Cycle chain drive cams are compatible with the stock splined chain sprocket used in 2000-06 Twin Cam 88 engines, but may be used in 1999 engines if the Harley-Davidson 2000-06 splined rear cam sprocket and appropriate 2000-06 sprocket spacer are used. For lifts over.510" S&S strongly recommends that the stock chain drive cam be upgraded to the S&S Cycle gear drive or to the H-D part number 25284-08. This kit upgrades the problematic spring loaded chain tensioners to more reliable hydraulic tensioners, and also upgrades the oil pump 640 Camshafts are used in S&S Cycle T124 engines, this cam makes horsepower! Intended for engines of 95 CID or more w/ compression ratios between 10.5:1 and 11.5:1. 3000-6000 rpm.