
S&S CYCLE Bolt-In Sidewinder® 4" Big Bore Kits
In stock items will be shipped within 1-3 days.
You can return the products within 14 days for a full refund, check our returns policy.
We accept many payment methods

In stock items will be shipped within 1-3 days.
You can return the products within 14 days for a full refund, check our returns policy.
The Bolt-In Sidewinder® 4" Big Bore Kits are designed for easy installation without the need for machining, balancing, or splitting the crankcases. You can install these kits even with the engine still in the frame. The kits feature a cast ductile iron sleeve in cast aluminum, which provides superior heat transfer.
For those looking to enhance their engine performance, 88" engines are boosted to 100", while 96" and 103" engines are boosted to 110". With a compression ratio of 10.5:1 (with stock 85cc heads), you can expect a streetable and dependable engine that responds well to performance cams. This complete kit includes cylinders, forged pistons, rings, piston pins, clips, and gaskets. Please note that these kits are not for use with S&S 79cc heads.
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We do not ship to the Canary Islands, Ceuta, or Melilla.
Shipping costs are calculated automatically at checkout based on destination and weight.
Free shipping may be offered for qualifying orders, as specified on our website.
Orders are processed within 1–2 business days after payment confirmation. Orders placed on weekends or public holidays are processed the next business day.
If your order is delayed or arrives damaged, you must notify us within 14 calendar days. We will investigate the issue and offer a resolution in accordance with applicable consumer protection laws.
In accordance with Royal Legislative Decree 1/2007 (Ley de Defensa de los Consumidores y Usuarios), you have the right to withdraw from your purchase within 14 calendar days from the date of receipt, without giving any reason.
To exercise this right, contact us via email or through our website, providing your order number and contact details.
If you want to return an item, please contact us first to give you detailed instructions.