# TBParts - Race Head, 88cc Big Bore and 20mm Carb Kit for Z50 CRF50 XR50 CRF70 > 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) > [Japanese Mini Bike Parts](https://tboltusa.com/store/japanese-mini-bike-parts-c-100.md) > [CRF50 Z50 & XR50](https://tboltusa.com/store/japanese-mini-bike-parts-crf50-z50-xr50-c-100_122.md) > [Big Bore & Engine Kits](https://tboltusa.com/store/crf50-z50-xr50-big-bore-engine-kits-c-100_122_124.md) > TBParts - Race Head, 88cc Big Bore and 20mm Carb Kit for Z50 CRF50 XR50 CRF70 - **Web page:** [this page on tboltusa.com](https://tboltusa.com/store/tbparts-race-head-88cc-big-bore-and-20mm-carb-kit-for-z50-crf50-xr50-crf70-p-883.html) - **Markdown:** [this page as markdown](https://tboltusa.com/store/tbparts-race-head-88cc-big-bore-and-20mm-carb-kit-for-z50-crf50-xr50-crf70-p-883.md) - **Generated:** 2026-11-10 12:01 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=883` All prices are in US dollars (USD). Shipping and any tax are worked out at checkout. ## Summary - **Part number:** TBW0936 - **Price:** $419.99 USD - **Stock:** 5 left. This is a kit: the count is how many complete kits can be built from the parts on hand. - **Reviews:** [4 reviews, average 5 of 5](https://tboltusa.com/store/reviews/tbparts-race-head-88cc-big-bore-and-20mm-carb-kit-for-z50-crf50-xr50-crf70-pr-883.html) - **Product id:** 883 - **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. - [Japanese Mini Bike Parts > CRF50 Z50 & XR50 > Big Bore & Engine Kits](https://tboltusa.com/store/crf50-z50-xr50-big-bore-engine-kits-c-100_122_124.md) - [Japanese Mini Bike Parts > CRF70 and XR70 > Carb Kits](https://tboltusa.com/store/crf70-and-xr70-carb-kits-c-100_36_490.md) - [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) - [Pit Bike Engine Parts > Chinese 50-110cc Performance](https://tboltusa.com/store/pit-bike-engine-parts-chinese-50-110cc-performance-c-51_37.md) - [TB Parts > CRF50 XR50 Z50 88-Up > CRF50 XR50 Z50 Big Bore and Stroker kits 1988 UP](https://tboltusa.com/store/crf50-xr50-z50-88-up-crf50-xr50-z50-big-bore-and-stroker-kits-1988-up-c-68_73_982.md) - [TB Parts > CRF70 XR70](https://tboltusa.com/store/tb-parts-crf70-xr70-c-68_77.md) - [TB Parts > Z50 88-99 > Z50 88-99 Big Bore and stroker kits](https://tboltusa.com/store/z50-88-99-z50-88-99-big-bore-and-stroker-kits-c-68_1056_1057.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) TBParts race head, 88cc Bore & 20mm Carb Kit. Performance and price make the TBParts 88cc w/ race head a real winner! **Key Features:** - Lightweight aluminum cylinder with steel sleeve - Cast in mounts on cylinder for aftermarket skid plates - Oversized cooling fins on cylinder for efficient heat dissipation - 52mm piston with rings, pin, & clips - Head gasket kit - High performance race camshaft - Race Head – Larger valves (25mm intake & 22mm exh) and porting for increased performance. Also has bigger cooling fins. Includes all necessary parts. - 20mm Performance carb assembly, which includes: 20mm carb, intake, heatstop, gaskets, mounting hardware/wrench, air filter and throttle cable **Recommended:** - 2 Size clutch tool - WHS-2274 - 2mm High speed drill bit - TRC-5526 - TB oil cooler kit w/intake mount - TBW1370 - TB 12 way rotating spacer 20mm - TBW0900 - Sta-bil fuel stabilizer - W-57-1129 **Application:** - Honda Z50 - 1988-1999 - Honda XR50 - All Years - Honda CRF50 - All Years - Honda CRF70 - All years - Honda XR70 - All years - Honda TRX70 - All years **Kit Includes:** - TBW0365 - Piston - TBW0206 - Gaskets - TBW0156 - Cylinder - TBW0125 - Carb - TBW0273 - Intake Manifold - TBW0301 - Throttle Cable - TBW0398 - Air Filter - TBW0300 - Race Cam - TBW0385 - Race Head & Valves Assembly - TBW0226 - Oil Pump - TBW0262 - CDI - TBW0294 - Jets - TBW0287 - Gasket Installation Note: It will save a lot of time and effort if the oil pump is installed while installing the bore kit (requires cylinder removal). 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 purchasing the shop manual for your bike available in our store. The parts are installed in the same manner as the OEM parts. Exceeds OEM Standard equipment ## 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 For a person: open [TBParts - Race Head, 88cc Big Bore and 20mm Carb Kit for Z50 CRF50 XR50 CRF70](https://tboltusa.com/store/tbparts-race-head-88cc-big-bore-and-20mm-carb-kit-for-z50-crf50-xr50-crf70-p-883.html), choose any options, press "Add to Cart", then check out from the cart. Payment is only ever entered by the person, on tboltusa.com's own checkout pages. For an AI assistant building a cart: `https://tboltusa.com/cart/new/item/883/qty/1` starts one with this product (the first value of every option, qty 1), `https://tboltusa.com/cart//add/item/883/qty/1` adds it to a cart you already started, and `https://tboltusa.com/cart//zip/` gives the shipping options to a US ZIP code. They answer JSON: give your customer the newest `cart_link`, a public cart link, safe to share. Or give the person one link that fills their own cart when they open it (a public cart link, safe to share; the first value of every option, qty 1): [Put TBParts - Race Head, 88cc Big Bore and 20mm Carb Kit for Z50 CRF50 XR50 CRF70 in my cart](https://tboltusa.com/cart/open/item/883/qty/1) 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/883/tbparts-race-head-88cc-big-bore-and-20mm-carb-kit-for-z50-crf50-xr50-crf70-1.0f6b1d38.jpg) - [Photo 2](https://tboltusa.com/store/img/p/883/tbparts-race-head-88cc-big-bore-and-20mm-carb-kit-for-z50-crf50-xr50-crf70-2.b4b2d7e5.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.