S&S Cycle 106-3688

These big bore pistons work with the stock 4" stroke flywheels to convert any 1999-'06 HD^® big twin engine from 88" to 97" displacement with 9.7:1 compression with stock heads. Stock cylinders may be bored to accommodate 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. 3.927" standard bore. Install Instructions Download

FITMENT DISCLAIMER

Fitment information is provided as a general reference only and is not guaranteed for any motorcycle, whether stock or modified. Compatibility may vary by year, model, and individual configuration.

Customers are responsible for verifying fitment prior to purchase. House of Harley-Davidson assumes no liability for purchases made based on incorrect or unverified fitment information.

Please contact our Parts Department with any questions before ordering at 414-282-2211