Zipper’s Sleeper 114/117″ to 128″ Black w/ Highlighted Fins Big Bore Kit

This powerful kit by Zipper’s transforms your 114″ or 117″ M8-powered machine to 4.250″ bore 128″ with a drop-on piston & cylinder kit. The Sleeper 128” kit is based around new-production cylinders and pistons, designed specifically by Zipper’s for durability and improved oil control. The new cylinders are then treated to the best precision boring and honing process you can find, as our technicians precisely measure each piston to provide skilled, old-fashioned sizing processes to the cylinders. Mounted in special torque plates, a CNC-hone is used to create a straight and true finish, topped off with brush-finish technology that requires minimal run time for ring seating while providing best power.

This is a hugely cost-effective way to increase the power of the Milwaukee-Eight® engine – with stock heads and a stock throttle body! While your engine is apart, we HIGHLY recommend that you do a full inspection of the cylinder heads for seat or guide issues, and Zipper’s provides new valve seals in the gasket kit for reassembly. If you are not equipped to perform the inspection or repairs to your stock heads, Zipper’s offers these services and more, just give them a call!

This is a hugely cost-effective way to increase the power of the Milwaukee-Eight® engine – with stock heads and a stock throttle body! While your engine is apart, we HIGHLY recommend that you do a full inspection of the cylinder heads for seat or guide issues, and we do provide new valve seals in the gasket kit for reassembly. If you are not equipped to perform the inspection or repairs to your stock heads, Zipper’s offers these services and more, just give them a call!

• This project requires a skilled technician. It is the responsibility of the person assembling the parts to check all clearances and assembly specifications.
• We highly recommend using Feuling’s ARP Cylinder Stud kit during install to avoid reusing stretched stock cylinder studs.

Not recommended for Tri-Glide or other three wheel models including conversion due to lugging nature of these bikes.