No Machining! Easy Installation!
Despite what some say, bigger is better, and if making something bigger is easy, that’s the best! A big bore kit is an easy way to achieve more displacement, and if you can install it without rebalancing flywheels or boring the crankcases, that’s about as easy as it gets. That’s the idea behind the new S&S® 106” big bore kits for 2007-up big twins. No need to bore or even split the cases, just do the cylinder swap. In addition to the ease of installation they look great because the cylinders are available with the same silver or black wrinkle powdercoat as stock, so they match the stock finish of your engine.

At 3.927” bore, these cylinders have the largest bore that we feel can safely be used in a cylinder with stock spigot diameter. In fact, this kit is only offered with S&S cylinders because, even though stock cylinders can be bored to fit the 3.927” pistons, we are not confident that the material used to make the stock cylinder liner and spigot is strong enough. The cylinder liner material in S&S cylinders is much stronger, and has proven its ability to stand up to the added power in numerous dyno pulls, street miles, and a lot of quarter mile drag strip runs. There is a trade-off for the ease of installation, which is that only one piston oversize is available for this kit. This really is as big as we are willing to go with a stock diameter cylinder spigot.

Performance Recommendations
The 106” big bore kit yields excellent results with stock cylinder heads, but a performance cam is recommended to get the best performance and to make the engine easier to turn over at start-up. However, for the best performance and easiest starting, we recommend S&S cylinder heads. In addition to the increased head flow and resulting increased power, S&S heads are machined to accept S&S electric or manual compression releases for easy, reliable starting

The SuperFlow® Cycledyne shows an increase of nearly 30 horsepower and 20 ft/lb of torque with the 106” top end kit. This engine was set up with stock cylinder heads, S&S 585 cams, stock EFI throttle body and teardrop air cleaner, and S&S performance mufflers. Stock curves are shown for comparison.

106" Big Bore Kits For 2007-up BT
Silver Powdercoat Finish . . . . . . . MSRP $695.00 106-3747
Black Powdercoat Finish. . . . . . . . . MSRP $695.00 106-3760