Complete Cylinders
About Complete Cylinders
The cylinder is the bore the piston travels in, and on an air-cooled engine its outside is finned to shed heat. Wear shows up as lost compression, hard starting, oil smoke and a drop in power, and a scored or damaged bore usually means a new cylinder instead of a repair. Riders also buy a cylinder to raise displacement or compression.
Read the title closely, because there are several forms. A cylinder only is the barrel alone. A cylinder kit generally adds a piston, and the contents are listed in the description. Cylinders come in standard bore, which matches the original size, or big bore, which is larger and adds displacement. Some are listed with a compression ratio, such as 11.8:1 or 14.4:1, and higher compression generally calls for fuel suited to it, so follow the maker's instructions. A bigger bore or compression change can also call for a new tune. Listings cover dirt bikes, ATV and UTV models such as the Kawasaki Teryx, and Harley-Davidson Shovelhead and touring models, and each is made for a particular engine and years.
Brands in this category include Athena, Colony, HardDrive, Drag Specialties and S&S Cycle. A new cylinder goes with Gaskets, Seals & Kits, Cylinder Bolts and often Cylinder Heads. The full group is Engines & Engine Parts. Pick your machine in the Ride Finder at the top of the page.
FAQs on motorcycle cylinders
What is the difference between a cylinder only and a cylinder kit?
A cylinder only is just the barrel, while a cylinder kit usually adds a piston and sometimes rings or gaskets. The contents vary, so read the listing. If you order a barrel alone, check whether you also need a matching piston, rings and gasket set.
What does big bore mean?
Big bore means the cylinder has a larger diameter than standard, which increases the engine's displacement. It requires a matching piston and usually changes how the engine runs, so a retune is often needed. Fitment depends on the maker's kit for your exact engine.
What does a compression ratio like 14.4:1 mean?
It compares the cylinder volume with the piston at the bottom of its stroke to the volume at the top. A higher ratio squeezes the mixture harder, which can raise power, and it also asks more of the fuel. Use the fuel and tune that the maker specifies.
How do I know if I need a new cylinder?
Look for deep scratches or scoring in the bore, a bore that is out of round or tapered beyond the service limit, or a damaged sealing surface. Low compression and smoke can point the same way. Measure with the tools and limits in your manual.
What else should I replace with a new cylinder?
Install a new piston and rings unless the kit includes them, and use new gaskets. Check the cylinder studs or bolts and the head gasket surface. Break the engine in as the maker's instructions describe, and change the oil afterward.
