S&S 128" M8 Big Bore Kit


The old saying is true.  There is no replacement for displacement!!!!  Already have a cammed M8 but want more fun?  This is the kit for you.  While the M8 114"/117" is a great improvement over previous engines, this bolt-on big bore kit takes your quest for fun to a whole new level.  Increasing your cylinder diameter to 4.25" and bumping the compression up to a completely streetable 11:1, this kit puts all the power you want at the twist of your wrist.  All of this is completed without the need to remove your motor from your bike or machine your cases - that means you can do the install in your garage.  The kit comes with pistons, new cylinders(no machining time), piston rings, wrist pins and clips, as well as new cylinder head and base gaskets.  Easy to follow instructions make this install a breeze.  The kit is available in three different finishes including black with highlights(stock), black granite(CVO), or black without highlights.

Fits:  All M8 motorcycles equipped with a 114"/117" from the factory

Note:  We highly recommend new cylinder head bolts.  Our https://fat-head-cycles.myshopify.com/admin/products/4725539209264 are a great choice or you can pick up part #10200303 from your local dealer.  


Shipping Delays

We are aware there are orders outstanding. Rest assured that your order has not been missed nor forgotten. Things here at Fat Head Cycles have changed drastically over the past few months and our small operation has had to adjust and adapt to maintain the accuracy and quality of our products. Our supply chains have been affected, distribution centers are backlogged and national shipping agencies have been severely affected by COVID19. Unfortunately, these things are completely out of our control.

The majority of orders containing Sony and Rockford products take between 21-28 BUSINESS days to custom assemble, ship and arrive at your doorstep. Once your order ships you will receive a SHIPPING CONFIRMATION email stating your order is on the way with tracking information. If you have not received this email your order is still in fulfillment que and is working its way up the list. Due to the fluid nature of the supply chain at this time, Fat Head Cycles CANNOT provide ETAs on bundles that have yet to ship as many times we are simply waiting on one small part or another to complete the package.

We here at Fat Head Cycles appreciate you as a customer and will always do the best we can to accommodate and fulfill your requests and your need for the best Harley Davidson audio and performance products in the industry. Thank you for your understanding.
We appreciate you,The Fat Head Cycles Team