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TBParts - 184cc Bore Kit, Race Head V2 w/ 28mm Carb Kit
GPX Pitster YX Piranha Lifan SSR

Vital Information
Part No TBW9040
Stock Level 2 Left
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170cc to 184cc race head V2, big bore kit, and 28mm carburetor performance kit

This is our latest complete kit to turn your YX/GPX/Zongchen 150cc to 160cc engine into an absolute beast! This kit includes our new Race Head V2 and while the new head may appear to be the same on the outside as our old KLX110 type race head, internally it has gone through numerous changes. The addition of roller rocker arms and a new camshaft are the biggest changes followed by bigger valves and ports. The exhaust valve is now stainless as well (21-4N material). This all adds up to a cylinder head that puts out a professional level of performance yet is still affordable for the privateer rider. The kit also includes an all aluminum ceramic plated 64mm cylinder (with skirt). This 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). We top off the roller head with a 28mm performance carb kit that is easy to tune and works much better with this setup than your stock Chinese 26mm carb. Additionally, our head gasket kit also includes a head o-ring set and exhaust gasket so you don't have to re-use your old ones or make a trip to your local dealer to get new ones and spend more money. The new top end consists of high quality parts and requires no machining to the cases - bolt on and go!

There are no installation instructions, but if you can replace your piston, you can install this kit. If you don't have any experience working on your engine, we highly recommend having a professional technician install this kit. The parts are installed in the same manner as OEM parts.


  • TBW0473 cam is stronger through the low and mid range with a little less on the very top.
  • TBW0577 cam is a little stronger on the very top with less through the low and mid range.

Key Features:

  • Race Head V2 - Roller rockers, 30mm intake valve, 24.5mm exhaust valve, 27mm intake port, 23mm exhaust port (valves installed).
  • The Race Camshaft V2-1 for the V2 head has been switched to our new version V2-2 for larger displacement engines (P/N TBW0577) and increases the performance.
  • All aluminum ceramic plated 64mm cylinder with skirt
  • We increased the skirt height and size on the lightweight high compression 64mm piston with rings, pin, & clips to increase reliability and service life (picture is not updated yet showing piston change)
  • Head gasket kit - includes the cylinder head o-ring set and an exhaust gasket.
  • 28mm Performance Carb (125 main/50 pilot)
  • Rear Facing Intake Kit - not forward facing like the KLX110 style (picture is not updated yet showing intake change)
  • Jet kit for varying conditions and exhausts


This kit is only for the YX and ZS 150cc to 160cc engines with KLX110 type top end.
The increase in displacement will depend on your stock engine size. With this kit:

  1. A stock 150cc engine will increase to 170cc
  2. A stock 155cc engine will increase to 177cc
  3. A stock 160cc engine will increase to 184cc


  • Sta-bil fuel stabilizer - W-57-1109

Kit Includes:

  • TBW0459 - Head, valves
  • TBW0473 OR TBW0577 - Cam
  • TBW1250 - Cylinder
  • TBW0503 - Top end gasket
  • TBW0590 - Piston
  • TBW0301 - Throttle cable
  • TBW0556 - Intake kit
  • TBW0327 - Jet kit
  • TBW0490 - Carb
  • TBW0491 - Air filter

Available Options:

Cam Choice:

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