Engine displacement is the volume, measured as the space between the top of the piston at bottom dead center (BDC) and top of the cylinder. The combustion chamber is in the head and is not part of this calculation.
This chart describes the engine displacement based on Bore and Stroke.
- Measurements are in millimeters (mm or mil).
- Bore is the diameter of the engine cylinder.
- Stroke length is the distance travelled by the piston during each cycle of the engine.
- Stroke is affected by the swing of the crankshaft during a rotation and the connecting rod length.
- Q - What is a 4 mil or 10 mil engine?
A - Stroke length is +4 millimeters or +10 mil over stock stroke of 54mm.
Keep scrolling to see some common engine builds below the chart.
Standard or Stock Engine Rebuilds
Standard Bore Engine = 64mm and is 347cc.
Stock Engine Rebuild = If an engine has worn or damaged stock cylinders, the top end of the engine can be rebuilt or repaired by boring the cylinders slightly larger than stock and installing larger pistons.
- 350-375 cc Stock Cylinders = 64.25mm - 66.5mm bore on a stock stroke (54mm) crankshaft. A stock crankshaft or an aftermarket stock stroke crankshaft can be used. Stock cylinders are bored larger than the stock 64mm bore. Displacement varies depending on how large the stock cylinders are bored to. This engine build is often done as a rebuild to repair the stock engine.
A stock engine rebuild can be done a few times over the years if needed. The engine will still perform as a stock engine or slightly better, and can still have a lot of life left in it.
Small Bore Engine Builds
Small Bore Engine = 64mm - 66.5mm. For increased performance, stock cylinders can be over bored (bored over stock diameter), and additional performance parts can be added. For more performance, an aftermarket cylinder kit can replace the stock cylinders, along with other performance parts, which might include a +4 mil crankshaft.
Small Bore Engine builds can be built with stock engine cases or Driveline Performance cases.
Some common small bore engine builds are:
- 385 cc Stock or Cheetah Cub Cylinders = 65 mm bore on a +4 mil stroke (58mm) crankshaft.
- 397 cc Stock or Cheetah Cub Cylinders = 66mm bore on a +4 mil stroke (58mm) crankshaft.
- 403 cc Stock Cylinders = 66.5mm bore on a +4 mil stroke (58mm) crankshaft. This is the biggest small bore engine you can build using a +4 mil crankshaft. This can be a stepping stone on the way up towards a Big Bore Engine Build.
Big Bore Engine Builds
Big Bore Engine = 68 mm or larger.
For +4mil engine builds, stock engine cases can be easily used. For +7mil or +10mil builds, a Driveline Performance engine case is recommended for strength and reliability. We often recommend a +10 mil over a +7 mil crank because there is not much price difference.
Some common big bore engine builds are:
- 421 cc Cheetah Cub = 68mm bore on a +4 mil stroke (58mm) crankshaft.
- 465 cc Cheetah Cub= 68mm bore on a +10 mil stroke (64mm) crankshaft.
- 472 cc Super Cub = 72mm bore on a +4 mil stroke (58mm) crankshaft.
- 521 cc Super Cub = 72mm bore on a +10 mil stroke (64mm) crankshaft.
- 611 cc Cheetah DM = 78mm bore on a +10 mil stroke (64mm) crank. (This is 611.63 cc, so it shows on the chart as 612 cc)
Re-Do Banshee can help you with any of these engine builds. We can help you select the parts for your DIY build, or we can rebuild or build your engine based on the plan you agree on with our help.
What is a Cylinder Package?
A cylinder package (or kit) serves as the core of an internal combustion engine and primarily consists of a cylinder, piston, and cylinder head. This is referred to as the top end of the engine. The bottom end of the engine includes the engine case halves and crankshaft.
Those looking for enhanced performance often replace the original cylinder package with an aftermarket package. These aftermarket cylinder packages are designed to enhance performance while maintaining reliability.
Cylinder Package Options - Which One?
In our opinion:
- Good = Stock Cylinders.
- Better = Athena Cylinder Package.
- Best = CP Industries, Inc: Cheetah Cub, Super Cub, or Cheetah DM Cylinder Package.
About the authors:
This article was written by Janel with plenty of help from Virgil. Virgil is the Banshee mechanic, and I am the website mechanic. I do own and ride a Banshee, which helps.
I need to make sure the products I or we put on our website have correct descriptions and options. I want our technical info to be accurate and helpful. Awhile back, I started creating internal cheat sheets for my own or our shop's use. This is how our Banshee Parts Reference blog began.
I thought my cheat sheets might also help others understand or find some helpful info. Writing and editing these articles helps me make better sense of the parts, fitment, and what goes with what.
I have a lot of draft ideas saved for blog articles I need to finish up at some point. Let me know if this one is helpful or if you think I need to correct something - on this article or anywhere else on our website! You can send an email to info@redo-parts.com - and your comments will be passed along to me.
Thanks ~Janel 😉👌