Engine Blocks & Accessories

Is your cylinder worn, scored or bored to the limit, or do you want more displacement? This category brings together cylinders and cylinder kits in standard bore, big bore kits and high-compression kits for engine projects where you want to rebuild or increase your engine's capacity. You choose based on model, year, bore and compression.

What the cylinder does for the engine

The cylinder forms the frame for the piston's movement, and the bore dimensions and surface condition affect compression, oil consumption and sealing. If the bore is worn, a new cylinder in standard bore – e.g. from Cylinder Works – can be an alternative to reboring the old one. Big bore kits, e.g. from S&S Cycle, increase the bore and thus the displacement, but may require matching pistons and gaskets. You'll find complete kits under cylinder kits.

How to choose a cylinder or cylinder kit

Start with the model and year, which are stated in the product name, and then choose based on these criteria:

• Bore: standard bore retains the original displacement, while big bore increases it and may require changes elsewhere in the engine.
• Compression: a high-compression kit (e.g. 14.1:1) can deliver more power, but typically places demands on fuel and ignition.
• Contents: some items are a single cylinder, others a kit with piston and gaskets – check the product description.
• The rest of the engine: more displacement may require different camshafts and valvetrain or new engine management.

Installation and break-in

Check piston clearance, ring gap and gasket thickness before assembling the engine, and follow the manufacturer's torque specifications. If you change the bore, the piston and rings must match – see pistons and piston rings. A new cylinder typically requires a break-in period with varying revs and an early oil change so the rings seat correctly. Whether the modification is road legal depends on the product and vehicle, and changed displacement may require an inspection – check this for the specific part number.

Frequently asked questions

Should I choose standard bore or big bore?

Standard bore is the right fit when you want to rebuild the engine to its original displacement. Big bore increases displacement and power potential, but may require different pistons, gaskets and adapted engine management. The choice depends on your goal and the rest of the engine's parts.

Can I fit a new cylinder without changing the piston?

It depends on the product. Some items are supplied as a kit with piston, others as a single cylinder. The piston and rings must match the bore, and new rings are typically recommended on a new cylinder surface.

How do I break in a new cylinder?

Follow the manufacturer's instructions. Typically you ride with varying revs and moderate load at first and change the oil early, so the rings seat and wear particles are removed from the engine.

Does big bore or higher compression require an inspection?

It depends on the product and vehicle. Changed displacement or power may require approval or an inspection before the vehicle can be used on the road. Check the requirements for the specific part number before you order.