Unlike the earlier Ironhead (that always used solids), the Harley-Davidson Evolution Sportster utilises hydraulic lifters. There are 3 year groups of these, and they are not interchangeable. We supply and fit these as part of every engine rebuild and anytime that the camshafts are changed in order to maintain reliability. Whilst a misfunctioning hydraulic unit can cause some aggravating valve train noises, failure of the roller, the needle bearings, or the axle, can be responsible for serious (and expensive), engine damage. It is false economy to cut corners here, so we only use high quality versions that have no known issues.
The 4 speed Evolution Sportsters use the same lifters that the Evolution Big Twin does. They run in seperate lifter blocks, similar (but not the same) to the Ironhead.
With the advent of the 5 speed Evolution Sportster in 1991, there were also a number of substantial engine modifications. The crankcases were redesigned and the lifters run directly in the case, not in seperate lifter blocks. These lifters are also noticably different, and are not used in any other Harley engine, although the Buell variants also have them.
The crankcases were redesigned again in 2000, and these engines use the same lifters as the Twin Cam. The further redesign in 2004, for the rubbermount motor, also uses the Twin Cam lifter. Buells and the XR1200 also have these.