Cylinders

Cylinders: the bore that sets your engine's displacement

The cylinder is where the piston runs, and its bore diameter is the single biggest lever on how much air and fuel your engine can move. Fit a standard-bore replacement when a jug is scored, worn past service limit, or nicked at the base gasket surface. Step up to a big bore cylinder kit when you want more displacement without splitting the cases for a stroker crank. On a V-twin that usually means new pistons, rings and gaskets going in at the same time, so it's a job you plan for, not one you rush.

What we stock

This category shows 10 products from 4 brands: S&S Cycle, Cylinder Works, Athena and TwinPower. Current pricing runs from $122 up to $1,559 for what's in stock right now, which is a range, not a fixed price. Every item here carries fitment data, and coverage spans model years from 1936 to 2024.

The fitment set leans toward Harley-Davidson Big Twin and Milwaukee-Eight platforms alongside powersports machines from Polaris, Yamaha, Kawasaki and Honda - including the Polaris General 1000 EPS, Polaris RZR 4 900, Yamaha YZ 125, Kawasaki KX 65 and Honda CRF 450 R. Concrete examples: the S&S Cycle 99-06 BT 4in bore cylinder kit at the top of the range, the S&S Cycle 97in big bore kit, the TwinPower M8 4.25in big bore pair, and standard-bore options like the Cylinder Works RZR 4 900 93mm cylinder, the Cylinder Works General 1000 EPS 93mm and the Athena YZ 125 54mm factory cylinder.

How to choose

The first fork is standard bore versus big bore. A standard-bore cylinder like the Cylinder Works and Athena pieces gets you back to stock spec and keeps your existing tune and jetting valid - the right call for a straight rebuild. A big bore kit like the S&S Cycle or TwinPower units adds displacement, but it changes the math on fueling and often means fresh pistons and gaskets to match.

The second fork is single jug versus paired or complete kit. A single cylinder covers a rebuild on one hole; the TwinPower listing is a pair, and the S&S kits bundle the cylinders together for a twin. Buy the format that matches how you're doing the work, and confirm bore size against your build plan before ordering.

What else you'll need

Plan on pistons sized to the bore, and don't reuse old seals - grab the right head gaskets or a full gasket kit for the teardown. While the top end is apart, check your bearings. Browse the rest of the Engine Components section for supporting parts.

Fitment help and ordering

Match year, make and model before you buy - every product here lists fitment. If you're unsure whether a jug fits your build, call our team at 813-535-5801 or reach us through contact us. All orders ship free, and Affirm and Katapult financing is available at checkout via our financing options.

Cylinders: the bore that sets your engine's displacement

The cylinder is where the piston runs, and its bore diameter is the single biggest lever on how much air and fuel your engine can move. Fit a standard-bore replacement when a jug is scored, worn past service limit, or nicked at the base gasket surface. Step up to a big bore cylinder kit when you want more displacement without splitting the cases for a stroker crank. On a V-twin that usually means new pistons, rings and gaskets going in at the same time, so it's a job you plan for, not one you rush.

What we stock

This category shows 10 products from 4 brands: S&S Cycle, Cylinder Works, Athena and TwinPower. Current pricing runs from $122 up to $1,559 for what's in stock right now, which is a range, not a fixed price. Every item here carries fitment data, and coverage spans model years from 1936 to 2024.

The fitment set leans toward Harley-Davidson Big Twin and Milwaukee-Eight platforms alongside powersports machines from Polaris, Yamaha, Kawasaki and Honda - including the Polaris General 1000 EPS, Polaris RZR 4 900, Yamaha YZ 125, Kawasaki KX 65 and Honda CRF 450 R. Concrete examples: the S&S Cycle 99-06 BT 4in bore cylinder kit at the top of the range, the S&S Cycle 97in big bore kit, the TwinPower M8 4.25in big bore pair, and standard-bore options like the Cylinder Works RZR 4 900 93mm cylinder, the Cylinder Works General 1000 EPS 93mm and the Athena YZ 125 54mm factory cylinder.

How to choose

The first fork is standard bore versus big bore. A standard-bore cylinder like the Cylinder Works and Athena pieces gets you back to stock spec and keeps your existing tune and jetting valid - the right call for a straight rebuild. A big bore kit like the S&S Cycle or TwinPower units adds displacement, but it changes the math on fueling and often means fresh pistons and gaskets to match.

The second fork is single jug versus paired or complete kit. A single cylinder covers a rebuild on one hole; the TwinPower listing is a pair, and the S&S kits bundle the cylinders together for a twin. Buy the format that matches how you're doing the work, and confirm bore size against your build plan before ordering.

What else you'll need

Plan on pistons sized to the bore, and don't reuse old seals - grab the right head gaskets or a full gasket kit for the teardown. While the top end is apart, check your bearings. Browse the rest of the Engine Components section for supporting parts.

Fitment help and ordering

Match year, make and model before you buy - every product here lists fitment. If you're unsure whether a jug fits your build, call our team at 813-535-5801 or reach us through contact us. All orders ship free, and Affirm and Katapult financing is available at checkout via our financing options.