# Engine & Engine Build Terms

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This is an article from the TBolt USA Tech Database, the store's free online library of pit bike technical info. The text below is the article as written.

Section: [How Things Work](https://tboltusa.com/store/how-things-work-tech-115.md)

## Article

Square Bore - An engine with the same bore x stroke , example 54mm x 54mm

Under Square - An engine with smaller bore than stroke , example 52.4mm x 57mm

Over Square - An engine with a larger bore than stroke , example 51mm x 57mm

Deck height - The distance from the top edge of the cylinder to the outer edge of the piston crown at top dead center.

Pin height - The distance from the center of the wrist pin to the upper edge of the piston crown or face.

## Tech Database sections

- [Tech Database home](https://tboltusa.com/store/tbolt-usa-pit-bike-minimoto-technical-info-database-tech-15.md)
- [Pit bike Buying and Ownership info](https://tboltusa.com/store/pit-bike-buying-and-ownership-info-tech-98.md)
- [Pit Bike Wiring Info](https://tboltusa.com/store/pit-bike-wiring-info-tech-56.md)
- [General Motorcycle Maintenance](https://tboltusa.com/store/general-motorcycle-maintenance-tech-95.md)
- [General Motorcycle Troubleshooting](https://tboltusa.com/store/general-motorcycle-troubleshooting-tech-97.md)
- [How Things Work](https://tboltusa.com/store/how-things-work-tech-115.md)
- [Identifying Parts, Bikes, and Engines](https://tboltusa.com/store/identifying-parts-bikes-and-engines-tech-96.md)
- [Parts Diagrams and Breakdowns](https://tboltusa.com/store/parts-diagrams-and-breakdowns-tech-120.md)
- [Pit Bike Installation Info](https://tboltusa.com/store/pit-bike-installation-info-tech-99.md)