Harley Davidson M-Eight 107" to 124" Bolt-On Big Bore Piston & Cylinder Kit. This Bolt-on kit will fit a stock 107ci M8 engine without the need to bore the cases of your 2017-19 Touring or 18-19 Softail with a stock 107ci Motor (4.375 Stroke). The cylinders in this kit increase your cylinder bore size from the stock diameter of 3.937" to 4.250".Increasing your engine's size to 124ci which, can produce 20% gain in performance with a proper tune. Combined with a the proper Cam, Exhaust, Intake, and Tune, this kit will turn your bike into an absolute beast. 107" to 124" Bolt-On Big Bore Piston & Cylinder Kit comes with. CP Carrillo 11:1 compression ratio 4.250 piston kit with coated skirts and X Forging (The Best). Cometic head and base gasket kit. NOTE: The compression ratio is based off of stock cylinder head combustion chamber volume. The item "Harley-Davidson M8 107 to 124 Bolt-On Big Bore Kit for Softail & Touring" is in sale since Saturday, April 13, 2019. This item is in the category "eBay Motors\Parts & Accessories\Motorcycle Parts\Engines & Engine Parts\Big Bore & Top End Kits". The seller is "stfuscott" and is located in Lafayette, Louisiana. This item can be shipped worldwide.