{"product_id":"gy6s-1100-1254-ncy-cylinder-head-2-valve-big-valve-61mm-172cc-genuine-gy6-54mm-spacing","title":"NCY CYLINDER HEAD (2 VALVE, BIG VALVE, 61mm 172cc ) GENUINE, GY6 *54mm SPACING*","description":"NCY 61mm BIG VALVE HIGH-FLOW CYLINDER HEAD \u003ch3\u003eGY6 125cc \/ 150cc PERFORMANCE • A-BLOCK • 54mm STUD SPACING\u003c\/h3\u003e \u003cp\u003eUpgrade the breathing capability of your GY6 performance engine with the \u003cstrong\u003eNCY Big Valve High-Flow Cylinder Head\u003c\/strong\u003e.\u003c\/p\u003e \u003cp\u003eDesigned for \u003cstrong\u003eA-Block GY6 engines with 54mm cylinder stud spacing\u003c\/strong\u003e, this performance cylinder head features oversized intake and exhaust valves, improved port design and an enlarged combustion chamber designed to work with \u003cstrong\u003e61mm big-bore cylinder setups\u003c\/strong\u003e.\u003c\/p\u003e \u003cp\u003eIncreasing valve size and improving airflow can help a properly tuned big-bore engine move more air through the combustion chamber, making this an excellent cylinder head for performance GY6 builds where the stock head becomes a restriction.\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eNCY SKU: 1100-1254\u003c\/strong\u003e\u003c\/p\u003e \u003ch2\u003eIMPORTANT FITMENT — READ BEFORE ORDERING\u003c\/h2\u003e \u003ch3\u003eA-BLOCK \/ 54mm STUD SPACING ONLY\u003c\/h3\u003e \u003cp\u003eThis cylinder head is designed for the older\/common \u003cstrong\u003eGY6 A-Block engine configuration using approximately 54mm cylinder stud spacing.\u003c\/strong\u003e\u003c\/p\u003e \u003ch3\u003eWILL NOT FIT:\u003c\/h3\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003eB-Block GY6 engines with 57mm stud spacing\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003eK-Block engines\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003eQMK engines\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003e161QMK engines\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eOther newer large-case GY6 engines using the wider stud pattern\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e139QMB \/ QMB139 50cc GY6 engines\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003cp\u003e\u003cstrong\u003eDO NOT ORDER BASED ON ENGINE DISPLACEMENT ALONE.\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003eThere are multiple versions of GY6 engines. A 150cc, 170cc or larger GY6-style engine does \u003cstrong\u003enot automatically mean this head will fit.\u003c\/strong\u003e\u003c\/p\u003e \u003ch3\u003eMEASURE YOUR CYLINDER STUD SPACING BEFORE ORDERING.\u003c\/h3\u003e \u003cp\u003eIf your engine is a \u003cstrong\u003e57mm B-Block or newer K-Block\/QMK configuration, this cylinder head WILL NOT FIT.\u003c\/strong\u003e\u003c\/p\u003e PERFORMANCE FEATURES \u003ch3\u003eBIG VALVE DESIGN\u003c\/h3\u003e \u003cp\u003eEquipped with oversized valves to increase potential airflow compared with a typical stock GY6 cylinder head.\u003c\/p\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003eIntake Valve:\u003c\/strong\u003e Approx. 27.8mm\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003eExhaust Valve:\u003c\/strong\u003e Approx. 22.9mm\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003cp\u003eThe larger valve area is especially beneficial on big-bore engines where increased displacement requires greater intake and exhaust flow.\u003c\/p\u003e \u003ch3\u003eHIGH-FLOW PORT DESIGN\u003c\/h3\u003e \u003cp\u003eThe intake and exhaust passages are designed to improve breathing for performance applications.\u003c\/p\u003e \u003cp\u003ePotential benefits on a properly matched and tuned engine include:\u003c\/p\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eImproved cylinder filling\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eIncreased intake flow\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eImproved exhaust flow\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eBetter throttle response\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eStronger performance at higher RPM\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eBetter support for big-bore engine combinations\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003cp\u003eActual performance will depend on the complete engine combination, including displacement, camshaft, carburetor, intake, exhaust, ignition and CVT tuning.\u003c\/p\u003e \u003ch3\u003eDESIGNED FOR 61mm BIG-BORE BUILDS\u003c\/h3\u003e \u003cp\u003eThis head is an excellent match for \u003cstrong\u003e61mm cylinder \/ big-bore combinations on compatible A-Block engines\u003c\/strong\u003e.\u003c\/p\u003e \u003cp\u003eA 61mm bore combined with the common approximately 57.8mm GY6 stroke produces approximately \u003cstrong\u003e169cc–171cc\u003c\/strong\u003e, commonly marketed as a \u003cstrong\u003e171cc big-bore setup\u003c\/strong\u003e.\u003c\/p\u003e \u003cp\u003eIt may also be useful in other compatible performance A-Block combinations, but piston-to-valve clearance, combustion chamber clearance and component compatibility must always be verified when building a modified engine.\u003c\/p\u003e TECHNICAL SPECIFICATIONS \u003cp\u003e\u003cstrong\u003eBrand:\u003c\/strong\u003e NCY\u003cbr\u003e\u003cstrong\u003eProduct:\u003c\/strong\u003e Big Valve High-Flow Cylinder Head\u003cbr\u003e\u003cstrong\u003eApplication:\u003c\/strong\u003e Performance GY6 4-Stroke Engines\u003cbr\u003e\u003cstrong\u003eEngine Block:\u003c\/strong\u003e A-Block ONLY\u003cbr\u003e\u003cstrong\u003eCylinder Stud Spacing:\u003c\/strong\u003e Approx. 54mm\u003cbr\u003e\u003cstrong\u003eRecommended Bore:\u003c\/strong\u003e 61mm performance applications\u003cbr\u003e\u003cstrong\u003eIntake Valve Diameter:\u003c\/strong\u003e Approx. 27.8mm\u003cbr\u003e\u003cstrong\u003eExhaust Valve Diameter:\u003c\/strong\u003e Approx. 22.9mm\u003cbr\u003e\u003cstrong\u003eExhaust Stud \/ Thread Size:\u003c\/strong\u003e 8mm\u003cbr\u003e\u003cstrong\u003eMaterial:\u003c\/strong\u003e Aluminum Alloy\u003cbr\u003e\u003cstrong\u003eCooling:\u003c\/strong\u003e Air-Cooled \/ Finned Design\u003cbr\u003e\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e Taiwan\u003cbr\u003e\u003cstrong\u003eSKU:\u003c\/strong\u003e 1100-1254\u003c\/p\u003e WHAT IS INCLUDED \u003ch3\u003eCYLINDER HEAD AS SHOWN \/ HEAD ASSEMBLY ONLY\u003c\/h3\u003e \u003cp\u003eThis listing is for the \u003cstrong\u003eNCY cylinder head itself\u003c\/strong\u003e.\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eNo additional engine components are included unless specifically pictured or stated in the listing.\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003eDo not assume that a cylinder kit, piston, rings, camshaft, rocker assembly, intake manifold, carburetor, gaskets, timing components or other engine parts are included.\u003c\/p\u003e REPLACEMENT \/ PERFORMANCE VALVES \u003cp\u003eCompatible NCY replacement\/performance valve set:\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eNCY High-RPM Racing Valve Set – Approx. 28mm Intake \/ 23mm Exhaust\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eValve Set SKU: 1100-1257\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003eAlways verify valve dimensions and compatibility before purchasing replacement valves.\u003c\/p\u003e ENGINE COMPATIBILITY \u003cp\u003eDesigned primarily for \u003cstrong\u003eGY6 125cc \/ 150cc A-Block engine families using the 54mm cylinder stud pattern\u003c\/strong\u003e, including compatible versions of:\u003c\/p\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003e152QMI – 125cc GY6\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003e157QMJ – 150cc GY6\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003e\u003cstrong\u003e1P57QMJ – compatible A-Block versions\u003c\/strong\u003e\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eOther GY6 A-Block engines using the same 54mm stud pattern\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003cp\u003eThese engines can be found in many Chinese and Taiwanese scooters, ATVs, go-karts and buggies.\u003c\/p\u003e \u003ch3\u003ePOSSIBLE VEHICLE BRANDS \/ APPLICATIONS\u003c\/h3\u003e \u003cp\u003eDepending on the specific engine installed:\u003c\/p\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eTaoTao\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eIce Bear\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eWolf Brand\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eBintelli\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eZNEN\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003ePeace Sports\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eRoketa\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eJonway\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eSUNL\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eTank\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eHammerhead\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eTrailMaster\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eCarter\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eYerf-Dog\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eVarious Chinese 125cc \/ 150cc scooters\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eVarious GY6-powered go-karts and buggies\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eVarious GY6-powered ATVs\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003ch3\u003eBRAND OR MODEL NAME DOES NOT GUARANTEE FITMENT.\u003c\/h3\u003e \u003cp\u003eManufacturers frequently used different GY6 engine versions in the same vehicle family. \u003cstrong\u003eVerify your engine code, cylinder stud spacing and existing cylinder-head dimensions before ordering.\u003c\/strong\u003e\u003c\/p\u003e DOES NOT FIT B-BLOCK OR K-BLOCK \/ QMK \u003cp\u003eThis distinction is extremely important when purchasing performance GY6 engine parts.\u003c\/p\u003e \u003ch3\u003eA-BLOCK\u003c\/h3\u003e \u003cp\u003e\u003cstrong\u003e54mm stud spacing\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003eThis is the engine configuration this NCY head is designed to fit.\u003c\/p\u003e \u003ch3\u003eB-BLOCK\u003c\/h3\u003e \u003cp\u003e\u003cstrong\u003eApproximately 57mm stud spacing\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eWILL NOT FIT.\u003c\/strong\u003e\u003c\/p\u003e \u003ch3\u003eK-BLOCK \/ QMK\u003c\/h3\u003e \u003cp\u003eNewer\/larger GY6-style engine platform commonly associated with engine codes such as \u003cstrong\u003e161QMK\u003c\/strong\u003e and related QMK configurations.\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eWILL NOT FIT.\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003eA cylinder head designed for the 54mm A-Block cannot simply be substituted onto the wider B-Block or K-Block\/QMK engine.\u003c\/p\u003e TUNING INFORMATION \u003cp\u003eInstalling a big-valve cylinder head changes the airflow capability of the engine. Proper tuning is necessary to take advantage of the upgrade.\u003c\/p\u003e \u003cp\u003eDepending on your engine combination, tuning may involve:\u003c\/p\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eCarburetor jetting\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eAir\/fuel mixture adjustment\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eLarger carburetor\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003ePerformance intake\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003ePerformance exhaust\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003ePerformance camshaft\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eValve adjustment\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eIgnition tuning\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eCVT tuning\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003ch3\u003eCARBURETOR JETTING\u003c\/h3\u003e \u003cp\u003eA big-bore\/high-flow engine will often require a richer fuel mixture than a stock engine.\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eDo not assume a specific #125 or #130 main jet is correct for every build.\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003eRequired jet size depends on the carburetor, air filter, intake, exhaust, camshaft, displacement, elevation, temperature and other modifications.\u003c\/p\u003e \u003cp\u003eStart from a safe baseline and properly tune the air\/fuel mixture for your individual engine.\u003c\/p\u003e \u003cp\u003eRunning a performance engine excessively lean can cause overheating and serious engine damage.\u003c\/p\u003e WHY UPGRADE TO A BIG-VALVE HEAD? \u003cp\u003eIncreasing displacement without improving cylinder-head airflow can eventually make the stock head a restriction.\u003c\/p\u003e \u003cp\u003eA properly matched big-valve head can allow a performance engine to:\u003c\/p\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eMove a greater volume of air\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eBetter support increased displacement\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eImprove high-RPM breathing\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eImprove throttle response\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eTake better advantage of performance camshafts\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eWork more effectively with larger carburetors\u003c\/p\u003e \u003c\/li\u003e \u003cli\u003e \u003cp\u003eSupport higher-output big-bore combinations\u003c\/p\u003e \u003c\/li\u003e \u003c\/ul\u003e \u003cp\u003eFor a \u003cstrong\u003e61mm A-Block GY6 performance build\u003c\/strong\u003e, the cylinder head is an important part of creating a properly matched engine combination.\u003c\/p\u003e \u003ch2\u003eBEFORE ORDERING — VERIFY THESE 3 THINGS\u003c\/h2\u003e \u003cp\u003e\u003cstrong\u003e1. Your engine is an A-Block GY6\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003e2. Your cylinder stud spacing is approximately 54mm\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003e3. Your cylinder\/bore and other engine components are compatible with this cylinder head\u003c\/strong\u003e\u003c\/p\u003e \u003ch3\u003e54mm A-BLOCK ONLY\u003c\/h3\u003e \u003cp\u003e\u003cstrong\u003eNOT FOR 57mm B-BLOCK\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eNOT FOR K-BLOCK\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eNOT FOR QMK \/ 161QMK ENGINES\u003c\/strong\u003e\u003c\/p\u003e \u003ch3\u003eNCY PERFORMANCE\u003c\/h3\u003e \u003cp\u003e\u003cstrong\u003eBIG VALVES • HIGH-FLOW DESIGN • 61mm BIG-BORE APPLICATION • MADE IN TAIWAN\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eSKU: 1100-1254\u003c\/strong\u003e\u003c\/p\u003e \u003cp\u003e\u003cstrong\u003eDistributed by JPstore\u003c\/strong\u003e\u003c\/p\u003e","brand":"ChinesePartsPro","offers":[{"title":"Default Title","offer_id":53556391215416,"sku":"1100-1254","price":103.6,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0011\/8898\/6997\/files\/2__05109.1570039266.jpg?v=1792867827","url":"https:\/\/www.chinesepartspro.com\/products\/gy6s-1100-1254-ncy-cylinder-head-2-valve-big-valve-61mm-172cc-genuine-gy6-54mm-spacing","provider":"ChinesePartsPro","version":"1.0","type":"link"}