Zipper’s Muscle 124” Big Bore Kit for the 107” M8 is the most powerful top end kit produced. The big breathing 4-valve heads on the M-Eight just love displacement, so this kit was developed for use with a 4.25” Bore drop-on cylinder. These cylinders are fitted with flat-top forged pistons and topped off with Zipper’s Stage III CNC headwork.
This kit includes CNC ported heads, bored cylinders, pistons, required gaskets and ring set. A core exchange is required. Click here for core exchange information. This kit can be modified for additional performance parts by reaching out to us.
Cycle Solutions Inc offers installation and dyno tuning at our two shop locations and at the events we attend for an additional cost of $1400.00. If you are interested in having this kit professionally installed and dyno tuned or have questions about this kit then please click below.
Fitment: 2017-Newer M-Eight Harley 107″ Touring Models
- Advanced port and valve designs works great with flat-top pistons
- Oversize 41mm Intake, 33mm Exhaust Valves
- Supports140+HP/TQ On 4.125-4.250″ Bore Engines
- Performance Valve Springs Set Up for Cam
- Decking to Achieve 92.5cc Combustion Chamber
Cylinders & Pistons:
- 4.25” (124”) Big Bore Cylinder Kit
- Forged 10:9:1 compression ratio flat-top pistons
- Gasket Kit
To get the most performance out of this Zipper’s 124″ Big Bore Kit it must be paired with the proper supporting products. We recommend a high cranking amp battery, a stepped exhaust system, Hi flow air intake, Thundermax Auto tune, a red shift 552 chain drive cam, 58mm-62mm CSR throttle body , 7.1 GPS Injectors and the S&S Roller Rocker Guardian Upgrade Kit.
PLEASE NOTE: If you order the S&S Roller Rocker Guardian Kit then you do not need to order the Feuling ARP kits because the Guardian kit includes the S&S Bolt Kit.