This is the largest big bore kit we offer for the Kawasaki Z125.

178cc Big Bore Performance Kit (67mm):

• Ceramic coated all aluminum cylinder (no steel sleeve)
• Lightweight high compression domed 67mm piston with rings, pin, & clips
• Head gasket kit – Now includes the cylinder head o-ring set and an exhaust gasket.

The all aluminum ceramic coated cylinder is lighter than a steel sleeved aluminum cylinder, reduces friction (increasing power), improves sealing, and provides better heat transfer (runs and cools down quicker). This new cylinder along with a complete head gasket kit and domed piston will provide the extra power to make your new Z125  a lot more fun to ride! These are high quality parts and definitely will dramatically increase the power and fun factor on your bike!

Important Notes:

This big bore kit is recommended for use only with our V2 Race Head.  For all other applications, please check clearances.

Installation requires engine dis-assembly and case boring. Therefore, we highly recommend a professional technician install this kit and the cases bored by a reputable machine shop.  Its also recommended that a professional technician make sure its tuned properly once installed. An aftermarket fuel controller is required and possibly an autotune will be needed to prevent a lean condition and damage to your engine.  Additionally, a performance exhaust is also recommended as the stock exhaust is restrictive and may cause your engine to run hotter.

Cylinder Skirt is 69×15.1mm, bore case to at least 70x16mm

This product is legal for closed-course competition use only; for racing vehicles (a competition vehicle not used on public highways). Intended for off-road use or race purposes; may not meet regulations of pollution controlled roads or highways. Not legal for vehicles registered and used in California.