S&S® 97" and 106" Big Bore Kit for 1999-Up Big Twins
No Machining! Easy Installation!
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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® 97" big bore kits for 1999-’06 big twins and the 106" big bore kits for 2007-up big twins. No need to bore or even split the cases, just do the cylinder and piston 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 physically 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
These big bore kits yield excellent results with stock cylinder heads, but a performance cam is recommended to get the best performance. To make the engine easier to turn over at start-up, we recommend the S&S Easy Start cams with built-in compression releases. For the absolute best performance, we recommend S&S cylinder heads with increased head flow and resulting power increase.
The dynamometer shows how much power is available with an S&S top end kit. The upper curves (red) show the performance of the 106” kit and the lower curves (blue) show the 97”. Both engines were set up with stock cylinder heads, stock EFI throttle body, teardrop air cleaner, and S&S performance mufflers and S&S 585 cams.
97" Big Bore Kits For 1999-’06 BT
Silver Powdercoat Finish MSRP $725.00
106-5974Black Powdercoat Finish MSRP $725.00
106-5975 106" Big Bore Kits For 2007-up BT
Silver Powdercoat Finish MSRP $725.00
106-3747Black Powdercoat Finish MSRP $725.00
106-3760
| S&S 97" and 106" Big Bore Kit Specifications |
| Bore | Model Year | Stroke
(Stock) | Displacement | Compression Ratio |
| Stock Heads | S&S 89cc Heads | S&S 79cc Heads |
3.927"
| 1999-’06 | 4" | 97" | 9.7:1 | 9.3:1 | 10.3:1 |
| 2007-up | 43/8" | 106" | 10.2:1 | 9.8:1 | 10.8:1 |
Note:
For most applications, we recommend the S&S single bore EFI throttle body with a teardrop air cleaner or tuned induction. 2008-up touring models will need to use the stock intake or Screamin’ Eagle® 58mm throttle body and Race tuner orPro EFI Super Tuner.
