{"product_id":"ptk-2670-protek-rc-cr21-3-port-21-off-road-engine-turbo-plug","title":"PTK-2670 ProTek RC CR21 3-Port .21 Off-Road Engine (Turbo Plug)","description":"\u003cp\u003e\u003cspan\u003eThe ProTek RC CR21 3-Port .21 Off-Road Engine is a great option for club racing on smaller tracks. With a freshly designed crankshaft and lightweight piston, the CR21 can deliver smooth power and crisp engine response. The engine shares the same bore and stroke as the highly successful ProTek Samurai engines, promoting peak engine performance. These features give budget-conscious racers an engine capable of extreme reliability and performance.\u003c\/span\u003e\u003cbr\u003e\u003cbr\u003e\u003cspan\u003eThe CR21 nitro engine uses a 9-fin cooling head to maintain optimal operating temperatures, and add great looks. The combustion chamber is designed to promote low to medium RPM ranges, perfect for club racing, while still offering high-performance output at high RPM. Internally, the engine uses a chamfered \"Knife-Edge\" connecting rod that reduces reciprocating mass and increases peak RPM. The J3-1 carburetor allows for precise tuning via the three adjustable needles. Two carburetor inserts (6mm - Orange and 7mm - Yellow) are included to aid in tuning conditions.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003eFeatures:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eExcellent option for off-road club racers\u003c\/li\u003e\n\u003cli\u003eGreat choice for smaller tracks \u003c\/li\u003e\n\u003cli\u003eAdvanced crankshaft design and lightweight piston deliver smooth crisp power\u003c\/li\u003e\n\u003cli\u003eBlack anodized 9-fin cooling head\u003c\/li\u003e\n\u003cli\u003eIncludes a ultra hot ProTek P3 turbo glow plug\u003c\/li\u003e\n\u003cli\u003e\"Knife Edged\" connecting rod decreases reciprocating mass while increasing rpm\u003c\/li\u003e\n\u003cli\u003e3-Needle J3-1 Carburetor allows for precise tuning\u003c\/li\u003e\n\u003cli\u003eIncludes 6mm and 7mm carburetor venturis\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSpecifications:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDisplacement:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e.21ci (3.49cc)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRecommended Application:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e1\/8 Off-Road\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBore:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e0.641in (16.27mm)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStroke:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e0.661in (16.80mm)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOutput:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e2.41hp @ 33,000RPM (2.45ps)\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003ePorting:\u003c\/strong\u003e\u003c\/li\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntake:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExhaust:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e1\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePractical RPM Range:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e4,000-40,000\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e13.43oz (381g)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eRecommended Exhaust:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePTK-2060:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eProTek R\/C 2060 Tuned Pipe w\/Manifold (\u003cstrong\u003ePTK-2060-1\u003c\/strong\u003e: pipe only)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePTK-2090:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eProTek R\/C 2090 Tuned Pipe w\/Manifold (\u003cstrong\u003ePTK-2090-1\u003c\/strong\u003e: pipe only)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eRecommended Glowplug:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePTK-2542: ProTek R\/C P3 Turbo Glow Plug (Ultra Hot)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eIncludes:\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e(1) CR21 3-Port .21 Off-Road Engine\u003c\/li\u003e\n\u003cli\u003e(1) P3 \"Glow Plug Turbo Glow Plug \"Ultra Hot\"\u003c\/li\u003e\n\u003cli\u003e(1) Exhaust Gasket\u003c\/li\u003e\n\u003cli\u003e(1) 7mm Venturi\u003c\/li\u003e\n\u003cli\u003e(1) 6mm Venturi\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"A MAIN","offers":[{"title":"Default Title","offer_id":50957189185814,"sku":"PTK-2670","price":329.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0066\/9974\/5341\/files\/Screenshot2026-01-20130125.jpg?v=1768943032","url":"https:\/\/www.mikeshobby.net\/products\/ptk-2670-protek-rc-cr21-3-port-21-off-road-engine-turbo-plug","provider":"Mike's Hobby","version":"1.0","type":"link"}