TB 143cc Big Bore Kit w/ V2 Race Head and Intake Manifold - Kawasaki Z125
TB 143cc Big Bore Kit w/ V2 Race Head and Intake Manifold - Kawasaki Z125
TB 143cc Big Bore Kit w/ V2 Race Head and Intake Manifold - Kawasaki Z125
TB 143cc Big Bore Kit w/ V2 Race Head and Intake Manifold - Kawasaki Z125
TB 143cc Big Bore Kit w/ V2 Race Head and Intake Manifold - Kawasaki Z125
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  • SKU: HTB-1057-143

TB 143cc Big Bore Kit w/ V2 Race Head and Intake Manifold - Kawasaki Z125

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TB 143cc big bore kit with V2 Big Valve Race Head! The 60mm bore is the biggest kit to run on the z125 Pro without machining your cases. Bolt-on ready, no machine work needed. Just add a Fuel controller. Comes with TB Intake Manifold.

The parts in this kit were developed to work flawlessly with each other to deliver a high level of performance at an affordable price. While we sell each part of this kit separately, running the combination of the big bore kit, race head, and intake kit are where you will see the most power and performance gains for the best value. These are high-quality parts and the increased power will not disappoint. Here are whats included in this kit:

143cc Big Bore Kit:

  • 60mm Ceramic coated all aluminum cylinder (no steel sleeve)
  • Lightweight high compression domed 60mm piston with rings, pin, & clips (will safely run on pump gas, 90-93 octane)
  • Head gasket kit – Now includes the cylinder head o-ring set and an exhaust gasket.

The all-aluminum ceramic coated cylinder is not only lighter than a steel sleeved aluminum cylinder, it is harder, reduces friction (increasing power), improves sealing, and provides better heat transfer (runs cooler and cools down quicker). Additionally, this is the biggest bore kit you can install without needing machining to the cases (case boring).

Race Head V2:

  • Forged anodized aluminum roller rockers
  • Huge 30mm intake and 24.5mm exhaust valves
  • Stainless Steel Valves (21-4N material)
  • 27mm intake port, 23mm exhaust port
  • Race Camshaft V2-1 (TBW0473)
  • Cam Sprocket

The combination of the above features in this Race Head V2 delivers huge power gains over the stock basic OEM cylinder head.

Intake Manifold Kit:

  • Port matched to the Race Head V2
  • Enlarged 26mm port on the throttle body side to work better with bored throttle bodies (also works well with stock throttle body)
  • Includes a port matched heat stop to prevent heat transfer to the intake (cannot run a heat stop with the stock intake manifold and some aftermarket head spacers)
  • Includes all mounting hardware
  • Includes a heat sensor extension harness so it can be relocated to the tappet or cam cover.

This intake manifold will ensure you will get the most power out of the Race Head V2!

Add a stroker crankshaft for even more power! Our 55mm stroker crank increases engine displacement and compression. If you add it to the:

143cc Big Bore Kit, will increase displacement to 155cc
165cc Big Bore Kit, will increase displacement to 177cc
178cc Big Bore Kit, will increase displacement to 194cc

Steady Garage R&D:

Additional recommended operational parts:

  • Oil Cooler
  • Aftermarket Fuel Controller: Aracer RC Mini 5, Bazzaz Z-Fi,or Dynojet Powercommander V w/Autotune module (for those who don't have access to a dynameter)
  • Upgraded clutch parts: performance clutch springs and/or clutch disc

Optional parts for higher performance:

  • Bored out throttle bodies
  • Aftermarket exhaust system
  • Chimera Short Ram Intake System

Professional installation is highly recommended!

Engine break-in, aftermarket fuel controller and special tune/autotune is required! Likewise with any major engine modification or bore up kits, it's now considered a high-performance race engine, extra attention and steps are needed to maintain a high-performance engine.


NO WARRANTY ON RACE ENGINE parts or engine bore up kits. There is no warranty stated or implied due to the unusual stresses placed on these parts and because we have no control over how they are installed and used. Steady Garage will not be held liable for any failure or damage caused directly or indirectly from the use of these products or engines. The installation and use of these products or engines shall be conclusive evidence that the user assumes full responsibility for any damage caused directly or indirectly by their use.

This product is NOT legal for sale, installation, or use on a pollution-controlled vehicle in the state of California. This product is NOT CARB legal. Legal only for racing vehicles in closed course competitions which will never be driven on a public right of way.

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; does not meet regulations of pollution-controlled roads or highways.

⚠ WARNING: California Proposition 65 www.P65Warnings.ca.gov.