# TBparts - 114cc Big Bore Kit with Race Head and TB 20mm Carb Kit for TRX90 Utilizing Stock Air Box

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## Summary

- **Part number:** TBW9239
- **Price:** $479.99 USD
- **Stock:** 8 left. This is a kit: the count is how many complete kits can be built from the parts on hand.
- **Product id:** 12113
- **Product last changed:** 2026-10-29

## 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.

- [TB Parts > TRX90](https://tboltusa.com/store/tb-parts-trx90-c-68_808.md)

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

## Description (the store's own text)

TB 114cc high compression big bore kit!

**Application:**

- TRX90 utilizing stock intake manifold and stock air box

**Key Features:**

- Lightweight aluminum cylinder with steel sleeve (huge weight savings over your stock cast iron cylinder)
- Cast in mounts on cylinder for aftermarket skid plates
- Oversized cooling fins on cylinder for efficient heat dissipation
- High compression 54mm piston with rings, pin, & clips (replaces your low compression dished or flat top piston)
- Head gasket kit
- High performance race camshaft (for the Race Head only)
- Race Head with Large valves (25/22mm) and better flow for increased performance.
- 20mm TB Performance carb

This will make a huge difference in performance over your stock setup and is a very quick and easy upgrade.

NOTE: TRX90 will not need High volume oil pump AND now this kit is set up for drop on install with no case mods with trx90

**Includes:**

- TBW0788 - Piston
- TBW0721 - Cylinder
- TBW0318 - Gasket
- TBW0385 - Race head
- TBW0300 - Race cam
- TBW0125 - Carb
- TBW0798 - Pilot jet kit
- TBW0294 - Main jet kit
- TBW0857 - Throttle cable
- TBW0133 - Dual feed petcock
- TBW0376 - Intake gasket
- TRC-10846 - Heat Spacer (For use in between the OEM manifold and carburetor)

## 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

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Payment: all major credit cards, PayPal, Apple Pay and Google Pay. Money orders by arrangement.

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

## Photos

- [Photo 1](https://tboltusa.com/store/img/p/12113/tbparts-114cc-big-bore-kit-with-race-head-and-tb-20mm-carb-kit-for-trx90-utilizi-1.cc0be507.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.