# TBParts - 1390 PISTON 60mm KLX - YX - ZS - Z125 High Compression Piston kit for V2 Head > 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) > [KLX 110 & DRZ 110](https://tboltusa.com/store/japanese-mini-bike-parts-klx-110-drz-110-c-100_123.md) > [Big Bore & Engine Kits](https://tboltusa.com/store/klx-110-drz-110-big-bore-engine-kits-c-100_123_126.md) > TBParts - 1390 PISTON 60mm KLX - YX - ZS - Z125 High Compression Piston kit for V2 Head - **Web page:** [this page on tboltusa.com](https://tboltusa.com/store/tbparts-1390-piston-60mm-klx-yx-zs-z125-high-compression-piston-kit-for-v2-head-p-11143.html) - **Markdown:** [this page as markdown](https://tboltusa.com/store/tbparts-1390-piston-60mm-klx-yx-zs-z125-high-compression-piston-kit-for-v2-head-p-11143.md) - **Generated:** 2026-11-04 18:53 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=11143` All prices are in US dollars (USD). Shipping and any tax are worked out at checkout. ## Summary - **Part number:** TBW1390 - **Price:** $79.99 USD - **Stock:** 1 left. - **Product id:** 11143 - **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. - [Japanese Mini Bike Parts > KLX 110 & DRZ 110 > Big Bore & Engine Kits](https://tboltusa.com/store/klx-110-drz-110-big-bore-engine-kits-c-100_123_126.md) - [Pit Bike Engine Parts > Piston Kits](https://tboltusa.com/store/pit-bike-engine-parts-piston-kits-c-51_96.md) - [TB Parts > KLX110 DRZ110 > KLX110 DRZ110 Big bore and Stroker Kits](https://tboltusa.com/store/klx110-drz110-klx110-drz110-big-bore-and-stroker-kits-c-68_1048_1049.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) This is a brand new 60mm (143cc) high compression piston kit we developed for our V2 Race Head due to market changes and requests. It will now be included in all of our 143cc kits that include the V2 Race Head (stock head bore kits will still use the previous piston, TBW0377). Prior to the Z125, most KLX110 customers were either using the 143cc V2 Race Head kits combined with a stroker crank (which bumps up compression); or on higher compression bigger bore kits (our 165cc kits and up); or they were just using the basic 143cc bore kit with stock head that has decent compression (due to a smaller combustion chamber). Because of those past scenarios, a high compression piston for the 143cc V2 Race Heads was not in high demand. With the arrival of the Z125 (and most of those customers not interested in boring their cases to go to a bigger bore) and with more KLX110 customers interested in remaining at 143cc for new pitbike race class rules, a higher compression piston became in demand so we developed one. **Kit Includes:** - Piston - Wrist Pin - Ring Set - Cir-clips **Specifications:** - 11:3 compression ratio – 143cc bore kit combined with the V2 Race Head - 12:2 compression ratio – 143cc bore kit combined with the V2 Race Head and our Stroker Crank In both combinations above, high octane pump gas should be used (Race gas is not required). Note: This piston kit will also work on the Chinese YX and ZS engines with a 60mm bore combined with our V2 Race Head. ## 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 - 1390 PISTON 60mm KLX - YX - ZS - Z125 High Compression Piston kit for V2 Head](https://tboltusa.com/store/tbparts-1390-piston-60mm-klx-yx-zs-z125-high-compression-piston-kit-for-v2-head-p-11143.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/11143/qty/1` starts one with this product (the first value of every option, qty 1), `https://tboltusa.com/cart//add/item/11143/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 - 1390 PISTON 60mm KLX - YX - ZS - Z125 High Compression Piston kit for V2 Head in my cart](https://tboltusa.com/cart/open/item/11143/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/11143/tbparts-1390-piston-60mm-klx-yx-zs-z125-high-compression-piston-kit-for-v2-head-1.png) ## 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.