The great thing about Harley-Davidson’s 883 Sportster is that it’s an easy bike to big-bore, since it’s basically the same motor as their 1200.
If you want to go bigger than 1200, though, S&S has introduced a new big bore kit that might be the ticket. They’ve come out with a 1250 cc conversion for 1986-2014 Sportsters that can bolt directly to stock crankcases. Besides an 883, you can also use the kit to big-bore a 1200, but the gains won’t be as extreme.
The kit comes with new pistons, cylinders and gaskets and will cost around a grand in the US; you can get the cylinders in a silver or a black finish. You can likely expect to pay more in Canada thanks to our exchange rate, but that’s still a pretty cheap way to hot-rod your mild-mannered 883.
Supposedly, by combining the big bore kit and S&S’s CNC ported heads, you can double an 883’s horsepower and torque, to roughly 100 hp and 82 ft-lb respectively. You can order domed or flat-topped pistons; the pistons have been designed to handle bigger valves (valve pockets work with two-inch valves). For more details, check out the kit here.