# TBParts - Roller Rocker Race Head V2 146cc Big Bore Kit China 120 & 125cc engines

> This is a plain-text (markdown) copy of a page on tboltusa.com, made for AI assistants. People see the same page at the HTML link below.

- **Breadcrumbs:** [Home](https://tboltusa.com/store/index.md) > [Pit Bike Engine Parts](https://tboltusa.com/store/pit-bike-engine-parts-c-51.md) > [Big Bore and Stroker Kits](https://tboltusa.com/store/pit-bike-engine-parts-big-bore-and-stroker-kits-c-51_24.md) > TBParts - Roller Rocker Race Head V2 146cc Big Bore Kit China 120 & 125cc engines
- **Web page:** [this page on tboltusa.com](https://tboltusa.com/store/tbparts-roller-rocker-race-head-v2-146cc-big-bore-kit-china-120-125cc-engines-p-55.html)
- **Markdown:** [this page as markdown](https://tboltusa.com/store/tbparts-roller-rocker-race-head-v2-146cc-big-bore-kit-china-120-125cc-engines-p-55.md)
- **Generated:** 2026-11-04 16:00 EST
- **Site guide for AI assistants:** [llms.txt](https://tboltusa.com/llms.txt)
- **Your list:** To list everything you have looked at in one page, with current prices and stock, add ids to this address (comma separated, up to 20 of each): `https://tboltusa.com/store/seen.md?p=55`

All prices are in US dollars (USD). Shipping and any tax are worked out at checkout.

## Summary

- **Part number:** TBW9127
- **Price:** $599.99 USD
- **Stock:** Out of stock. It cannot be added to the cart right now. A person can ask to be emailed when it is back: [Get on the List](https://tboltusa.com/store/contact_us.php?pid=55&stockcheck=true) ([Contact us](https://tboltusa.com/store/contact_us.md)) This is a kit: the count is how many complete kits can be built from the parts on hand.
- **Product id:** 55
- **Product last changed:** 2026-10-10

## What it fits

The store lists a part under each bike or engine model it is meant for (the categories below) and may name models in the description. Do not assume it fits a bike or engine that is not named here; ask the store first.

- [Pit Bike Engine Parts > Big Bore and Stroker Kits](https://tboltusa.com/store/pit-bike-engine-parts-big-bore-and-stroker-kits-c-51_24.md)
- [TB Parts > Chinese Engines](https://tboltusa.com/store/tb-parts-chinese-engines-c-68_70.md)

Where a fitment line says "All", it means all years of the model named on that line, not all bikes.

## Notes the store shows with this product

**Al****l of our 125cc engine big bore kits are for** **78mm tall cylinder engines only**

**Most China 125cc pitbike engines are 69mm tall cylinder type engines Your engine MUST have a 78mm tall cylinder to use this kit.**

Please see TECH LINK for more details

[tboltusa.com/store/tech.php](https://tboltusa.com/store/tech.php?pID=84/Engine+Info+for+Kits)

## Description (the store's own text)

TBparts roller rocker race head V2 with 146cc big bore kit for China 120 & 125cc engines. Highest performance race head on the market with full parts support in stock!

**Key Features:**

- Roller rocker arms exactly like the V2 head for the KLX110
- 28.5mm intake Valve
- 23.5mm Exhaust Valve
- 5mm valve stem
- 23mm exhaust port
- Matching high compression piston head kits include all hardware
- 57mm piston with rings, pin, & clips
- 57mm all aluminum cylinder with steel liner
- High performance race camshaft (for the Race Head only)
- Head gasket kit
- OD of cylinder skirt is 59mm

**Recommended:**

- Sta-bil fuel stabilizer - W-57-1129
- 26mm Intake - TBW0433

**Application:**

- China 120cc & 125cc engines with a 14mm wrist pin

**Kit Includes:**

- TBW0751 - V2 Race head
- TBW0821 - V2 Head bolt kit
- TBW0752 - Cam
- TBW0754 - V2 Head cover set
- TBW0414 - Cam sprocket
- TBW0824 - Piston
- TBW0862 - Top end gasket set
- TBW0601 - Cylinder

See the performance info section for additional information on our performance parts.

## Tech articles for this product

The TBolt USA Tech Database is the store's free online library of pit bike technical info. The articles below are linked from this product's own page.

- [Engine Info for Kits](https://tboltusa.com/store/engine-info-for-kits-tech-84.md)

## Shipping and returns

- Flat rate shipping is $8 for parts orders under $75 and free for most parts orders over $75, within the continental 48 states. Heavy items (engines, complete bikes, suspension) are excluded.
- Full shipping policy: [Shipping policies](https://tboltusa.com/store/shipping-policies-i-6.md)
- Returns: the store's own policy page says how returns, exchanges and cancellations work. Please read it before buying: [Returns, Exchanges and Cancellations](https://tboltusa.com/store/returns-exchanges-and-cancellations-i-11.md) The page begins: "All products returned to T Bolt USA must be reviewed and approved."

## How to buy

This item is out of stock, so it cannot go in the cart now (see Stock above).

Cart: [Shopping cart](https://tboltusa.com/store/shopping_cart.php)

## Photos

- [Photo 1](https://tboltusa.com/store/img/p/55/tbparts-roller-rocker-race-head-v2-146cc-big-bore-kit-china-120-125cc-engines-1.jpg)

## Support

Since 2004, every purchase from TBolt USA includes access to technical support from our staff of experts and our online [Pit Bike Technical Info Database](https://tboltusa.com/store/tbolt-usa-pit-bike-minimoto-technical-info-database-tech-15.md)!

We have all necessary support parts on hand.

*Most* orders ship same, or next business day, unless otherwise noted above.