S&S Cycle 2007+ BT 3.937in x 4-3/8in Piston Set

These big bore pistons work with the stock 4-3/8" stroke flywheels to convert any 2007-'16 HD® big twin engine from 96" or 103" to 107" displacement with 10.4:1 compression with stock heads. Stock cylinders may be bored to accomodate larger pistons, but we recommend S&S 3.927" bore cylinders which feature high strength alloyed cast iron liners. Pistons are compatible with stock rods with tapered wristpin ends. S&S® 3.927" bore pistons are machined to such close tolerances that it is not necessary to measure the piston. Just bore cylinders to nominal diameter +/- 0.0005" for correct clearance. Additionally, the low friction coating on the piston skirt makes taking measurements very difficult. 3.937" standard bore.

Note for Pistons, Rings, Rotors, Rods and engine internals

Unless otherwise specified, some brands supply brake rotors, pistons, strut mounts, rods and rings separately. In some cases, titles may indicate plural, or 'set' - eg the term “ring set” often refers to the rings for a single piston only. If you’re unsure about what’s included with this product, please contact our team for clarification.

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