Just available from S&S Cycle, these proven performance kits don’t need any machining, any rebalancing. Just bolt on in pistons and cylinders (4” bore, 4 3/8” stroke) in place of the stock ones. Installation can be done with engine still in the bike!
Kit works well with stock cylinder heads, or let S&S CNC port those heads for even more power. The factory 1999-2006 Twin Cam engines will roll up to 100” and the 2007-later models (except 2017 touring models) will become 110” monsters.
The 10.5:1 compression makes for a very street able and dependable engine that also responds well to performance cams. S&S 4” bore kits are available in color matched silver or wrinkle-black powder coat finish. See your local S&S Dealer or go to S&S Bolt-On 4” Bore Kits.