Bolt-In Sidewinder 4" Big Bore Kits / '99-'17 Twin Cams
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The S&S Bolt-In Sidewinder 4" Big Bore Kit raises a '99-'17 Twin Cam to 100 or 110 cubic inches with no machining and no case boring.
No Shipping to California.
Every other route to this much displacement sends your cases to a machine shop. The Sidewinder does not. It bolts in, which turns a multi week project into a job a competent shop finishes in a day. An 88" motor becomes a 100, and a 96 or 103 becomes a 110, without the engine ever leaving the frame in pieces.
How the Sidewinder Kit Works
A cast ductile iron sleeve inside cast aluminum handles heat transfer, keeping cylinder temperature down where a bigger bore would otherwise raise it. Compression lands at 10.5:1 with stock 85cc heads, which is a dependable streetable number that responds well when performance cams are added later. The kit is complete: cylinders, forged pistons, rings, piston pins, clips and gaskets. Made in the USA.
Sidewinder Big Bore Kit Specifications
- Fits '99-'17 Twin Cam models
- 100" kits for '99-'06 Twin Cam, 110" kits for '07-'17 Twin Cam
- Bolt-in design, no machining or case boring required
- Cast ductile iron sleeve in cast aluminum for heat transfer
- 10.5:1 compression with stock 85cc heads
- Includes cylinders, forged pistons, rings, piston pins, clips and gaskets
- Finishes: silver or wrinkle black
- Made in the USA
Before You Order the Sidewinder
Not for use with S&S 79cc heads. Not recommended for Trike models or for use on Twin Cooled models.
⚠️ VERIFY your model year and head configuration before ordering. Retuning is required after installation.
Complete Your Sidewinder Build
The Sidewinder is a no-machining kit, which keeps the job in your own garage — but it still needs a retune and fresh gaskets. See how bolt-in kits compare to machined builds in our big bore kit guide.
- Tuners & Fuel Systems — required after the swap
- Gaskets & Seals
- Engine Tools — piston ring compressor, torque tools
- Feuling Parts — cams and lifters to match
- Oil, Filters & Lubes — break-in oil
- Shop all S&S Cycle
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