{"about":"Prices are for United Kingdom in GBP. Every URL here is a plain path you can fetch directly.","product":{"basketKey":"5b98e2df7426","name":"CYLINDER FULL KIT 85mm YAMAHA YZ 250F 21-23, ATHENA P400485100105 304CC BIG BORE, (Piston included)","sku":"56-K250.85.KIT2","brand":"Athena","mpn":null,"gtin":null,"condition":"new","inStock":true,"stock":1,"price":{"amount":749.21,"formatted":"£749.21"},"summary":"Athena big bore cylinder full kit, part reference P400485100105, increases displacement to 304 cc via an 85 mm bore. This kit delivers higher torque and power across the RPM range. The cylinder is made from high-silicon aluminium alloy with an oversized steel liner, fused using a co-casting process for heat transfer and combustion sealing. It includes a forged, CNC-machined piston with a molybdenum disulphide coating to reduce friction and a DLC-coated piston pin for hardness and durability. Piston rings and pin are included, along with a complete gasket set featuring an MLS head gasket made from laser-cut stainless steel. A GET Boost electronic module, pre-calibrated for this kit, is also included. The GET Boost installs without ECU or wiring modifications, connecting via a dedicated harness to the injector and throttle body. Bore diameter is 85.00 mm and displacement is 304.00 cc.","attributes":[],"image":"https://b69270dd6ab1.blob.upstash.io/oracle/oro2u/56-K250_2E85_2EKIT2/2a812c80f2242015.jpg","images":["https://b69270dd6ab1.blob.upstash.io/oracle/oro2u/56-K250_2E85_2EKIT2/2a812c80f2242015.jpg"],"description":"Athena big bore cylinder full kit, part reference P400485100105, increases displacement to 304 cc via an 85 mm bore. This kit delivers higher torque and power across the RPM range. The cylinder is made from high-silicon aluminium alloy with an oversized steel liner, fused using a co-casting process for heat transfer and combustion sealing. It includes a forged, CNC-machined piston with a molybdenum disulphide coating to reduce friction and a DLC-coated piston pin for hardness and durability. Piston rings and pin are included, along with a complete gasket set featuring an MLS head gasket made from laser-cut stainless steel. A GET Boost electronic module, pre-calibrated for this kit, is also included. The GET Boost installs without ECU or wiring modifications, connecting via a dedicated harness to the injector and throttle body. Bore diameter is 85.00 mm and displacement is 304.00 cc.","descriptionMarkdown":"### Athena Big Bore Cylinder Full Kit 304cc for Yamaha YZ250F\n\nUpgrade your Yamaha YZ250F with the Athena Big Bore Cylinder Full Kit. This comprehensive kit increases displacement to 304cc through an 85mm bore, delivering significant gains in torque and power across the entire RPM range.\n\nThe cylinder is constructed from a high-silicon aluminum alloy featuring an oversized steel liner. This liner is fused using a co-casting process, ensuring excellent heat transfer and robust combustion sealing. The kit includes a precision CNC-machined forged piston with a molybdenum disulfide coating to minimize friction. For enhanced durability, the piston pin features a DLC coating.\n\nThis kit comes complete with all necessary components for a full installation:\n\n\t\n- Forged piston\n\t\n- Piston pin\n\t\n- Piston rings\n\t\n- Complete gasket set\n\t\n- MLS head gasket made from laser-cut stainless steel\n\t\n- GET Boost electronic module, pre-calibrated for this specific configuration\n\nThe included GET Boost module is designed for a hassle-free installation, requiring no modifications to the ECU or wiring. It connects directly to the injector and throttle body, utilizing a dedicated harness and coming pre-mapped to optimize performance with the new cylinder configuration.\n\n**Key Features:**\n\n\t\n- Increases displacement to 304cc with an 85mm bore\n\t\n- Boosts torque and power output\n\t\n- High-silicon aluminum alloy cylinder with steel liner\n\t\n- Co-cast steel liner for superior heat transfer and sealing\n\t\n- CNC-machined forged piston with low-friction coating\n\t\n- DLC-coated piston pin for maximum hardness and durability\n\t\n- Includes piston, rings, pin, and full gasket set\n\t\n- MLS stainless steel head gasket\n\t\n- Plug-and-play GET Boost module pre-mapped for the kit","weightGrams":null,"fitments":[],"collections":[],"links":{"page":"https://www.2brosparts.com/products/cylinder-full-kit-85mm-yamaha-yz-250f-21-23-athena-p400485100105-304cc-big-bore-","buyOneNow":"https://www.2brosparts.com/api/agent/checkout/GB/5b98e2df7426:1","basketWithThis":"https://www.2brosparts.com/api/agent/basket/GB/5b98e2df7426:1"}},"market":{"country":"GB","countryName":"United Kingdom","locale":"en-gb","currency":"GBP","exchangeRateFromGbp":1,"pricesIncludeUkVat":true,"checkoutTax":null,"delivery":[{"name":"Standard","description":"Orders £15.00–£59.99 · 2–4 business days","carrier":null,"estimatedDays":"2–4 business days","price":{"amount":4.99,"formatted":"£4.99"},"free":false,"minimumOrder":{"amount":0,"formatted":"£0.00","gbp":0},"weightGrams":null},{"name":"Standard","description":"Orders £60.00 and up · 2–4 business days","carrier":null,"estimatedDays":"2–4 business days","price":{"amount":0,"formatted":"£0.00"},"free":true,"minimumOrder":{"amount":60,"formatted":"£60.00","gbp":60},"weightGrams":null}],"storeUrl":"https://www.2brosparts.com"},"navigate":{"start":"https://www.2brosparts.com/api/agent","search":"https://www.2brosparts.com/api/agent/search/GB/{words+joined+with+plus}"},"howToBuy":{"summary":"Build a basket for the shopper and give them one checkout link. Every URL is a plain path (no query string) and a GET. Nothing is stored between calls.","checkoutLinkFormat":"https://www.2brosparts.com/api/agent/checkout/GB/{basketKey}:{quantity},{basketKey}:{quantity}","steps":["1. Find products: follow links in these responses, or fetch https://www.2brosparts.com/api/agent/search/GB/{words+joined+with+plus} (e.g. https://www.2brosparts.com/api/agent/search/GB/brake+pads). Every product has a basketKey.","2. Optional check: https://www.2brosparts.com/api/agent/basket/GB/{basketKey}:{quantity},{basketKey}:{quantity} returns stock, totals per delivery option and the checkout link.","3. Give the shopper the checkout link. Opening it fills their basket with exactly these items (replacing what was there) and opens checkout for United Kingdom. They pay on 2brosparts.com through Stripe."],"noFetchNeeded":"You can write the checkout link yourself from basketKeys and quantities; nothing has to be fetched first. Each product also has links.buyOneNow, a ready link for one unit.","stateless":"Nothing is saved on our side. The items part of the URL is the whole basket: to change it, write the link again with the new list.","itemsFormat":"basketKey:quantity pairs joined by commas, e.g. 04f24aad4d68:2,7c1e9a0b3f2d:1. Quantity defaults to 1. Up to 50 products, 100 each.","country":"GB is the shopper's delivery country. Swap it for theirs (US, DE, FR…) in any URL; currency, tax and delivery follow it.","tips":["Put everything the shopper wants in one link.","Optionally add your name as a last path segment on checkout links (…/checkout/GB/<items>/claude) so the sale is credited to you.","The checkout link is for the shopper's browser. Do not open it yourself.","Signed-in trade account holders see their trade prices at checkout."]}}