What does the '.030in' designation mean for these piston rings?

The '.030in' indicates that these rings are intended for cylinders that have been bored out by 0.030 inches larger than their original factory size. This is common during engine rebuilds to clean up cylinder walls or increase displacement.

How many cylinders does one pack of these piston rings cover?

This pack contains enough piston rings to service two cylinders. If your Big Twin engine has more than two cylinders, you will need to purchase additional sets.

Are these piston rings suitable for all 1984+ Big Twin engines?

These rings are specifically for Big Twin engines with a 4-1/8 inch bore that has been machined to a 0.030 inch oversize. Always verify your engine's bore size and condition before ordering.

Specifications

Brand: S&S Cycle
Part #: 940-0017
UPC: 940-0017

S&S Cycle 1984+ BT 4-1/8in .030in - 2 Pack

Name: S&S Cycle 1984+ BT 4-1/8in .030in - 2 Pack
Brand: S&S Cycle
SKU: s-s-cycle-s-s-cycle-1984-bt-4-1-8in-030in-2-pack-t14-661733
Price: 171.74 USD
Availability: BackOrder

$171.74

On Backorder — Expected to ship by May 7, 2026

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

S&S Cycle 1984+ BT 4-1/8in .030in piston rings. Essential for engine rebuilds needing precise cylinder sealing.

Key Features

Fits 1984 and later Big Twin engines.
Designed for 4-1/8 inch bore cylinders honed to 0.030 inch oversize.
Thin ring design for reduced friction and improved responsiveness.
Includes rings for two cylinders.
From S&S Cycle, a popular name in motorcycle engine performance.

These piston rings are designed for 1984 and later Big Twin engines with a 4-1/8 inch bore that has been honed to 0.030 inch oversize. Not CARB approved and cannot ship to California.

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About this part

Product Details

If you're rebuilding the top end of your 1984 and later Big Twin motorcycle, getting the right piston rings is crucial for proper engine performance. These S&S Cycle piston rings are designed to fit 4-1/8 inch bore cylinders that have been honed to a 0.030 inch oversize. They are a key component in ensuring your engine seals combustion gases effectively, which translates to good power and efficient operation.

S&S Cycle is well-known for making solid engine components for performance and custom builds. This set includes rings sized for two cylinders, so you'll have what you need to get both pistons properly seated. The thin ring design is often chosen for its ability to reduce friction and improve responsiveness in performance applications. Make sure your engine is running its best by using well-made parts like these.