Feature three-piece assembled flywheels with shafts. Do not require any motor case modification. 4-1/2" stroke. 103" stock motors or motors with factory 95" kits require piston kit only; stock or S&S cylinder heads can be used. Stock cylinders will require boring to 3.875". Made in the USA. Fuel-injected motors will require recalibration of the fuel-injection system.. This project requires a skilled technician. It is the responsibility of the person assembling the parts to check all clearances and assembly specifications..