{"product_id":"zippers-performance-thundersport-cylinder-heads-harley-tc-07-17-copy","title":"ZIPPERS PERFORMANCE THUNDERSPORT CYLINDER HEADS HARLEY EVO","description":"\u003cp\u003eZIPPERS PERFORMANCE THUNDERSPORT CYLINDER HEADS HARLEY EVO\u003c\/p\u003e\n\u003cp\u003eSELECT LEVEL OF HEADWORK IN OPTIONS \u003c\/p\u003e\n\u003cp\u003eTHESE ARE AN EXCHANGE ITEM \u003c\/p\u003e\n\u003cp\u003eSTAGE 1-\u003cspan\u003eThese heads receive our Stage I Performance Valve Job, 1.850” O.S. Valves, new guides and 7mm conical springs. The head gasket surface will be skim decked to assure a true\/flat sealing surface. This is a high quality upgrade for a budget build! Combustion chambers are stock 78 to 83 cc.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eSTAGE 2-Special high velocity port design with 1.850\/ 1.610 valves. Valves and\u003cbr\u003e7mm conical springs. Designed for engines with factory or aftermarket flat top\u003cbr\u003epistons or dome pistons. The combustion chambers are 78 cc to 82 cc range as\u003cbr\u003ecast.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eSTAGE 3-Owners of Evolution® powered Big Twins can increase their engine’s output with a set of our CNC-ported EV heads! The factory casting is CNC-machined to our proven high torque, high power port shapes and the valve sizes are increased to 1.900” intake and 1.630” exhaust. Ductile iron Step-Lock guides are fitted and topped off with high quality Viton® seals and a performance spring kit. The head gasket surface is decked for flatness before final assembly.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e \u003c\/span\u003e\u003c\/p\u003e","brand":"ZIPPERS","offers":[{"title":"STAGE 1 WORKHORSE","offer_id":55576917344424,"sku":"zippers-performance-thundersport-cylinder-heads-harley-evo","price":1599.95,"currency_code":"CAD","in_stock":true},{"title":"STAGE 2 CNC","offer_id":55576917377192,"sku":"zippers-performance-thundersport-cylinder-heads-harley-evo","price":2099.95,"currency_code":"CAD","in_stock":true},{"title":"STAGE 3 CNC","offer_id":55576917409960,"sku":"zippers-performance-thundersport-cylinder-heads-harley-evo","price":2299.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0747\/8273\/6552\/files\/ZIPPERS_EVO_HEADS.jpg?v=1780376177","url":"https:\/\/speedguyscanada.com\/products\/zippers-performance-thundersport-cylinder-heads-harley-tc-07-17-copy","provider":"THE SPEED GUYS CANADA ","version":"1.0","type":"link"}