{"product_id":"s-s-steel-breather-valve-std-for-harley-davidson-2","title":"S\u0026amp;S, Steel Breather Valve. Std For Harley Davidson","description":"High quality steel breather valve for use as stock or high performance replacement.\u003cbr data-mce-fragment=\"1\"\u003e Note: S\u0026amp;S breather valves come with elongated breather holes to increase the duration of the vacuum, allowing more oil to be drawn from the cylinder heads.\u003cbr data-mce-fragment=\"1\"\u003e This has no disadvantage in any model year, either stock or Big Inch engine.\u003cbr data-mce-fragment=\"1\"\u003e Note: that steel breathers require steel breather valve spacers.\u003cbr data-mce-fragment=\"1\"\u003e Plastic breathers require plastic spacers.\u003cbr data-mce-fragment=\"1\"\u003e Do not mix steel and plastic parts.\u003cbr data-mce-fragment=\"1\"\u003e Note: A .030\" oversize breather is available to save worn or damaged crankcases as 518662.\u003cbr data-mce-fragment=\"1\"\u003e A JIMS breather hole reamer (MCS 978343) will ream the damaged hole to +.030\" so a +.030\" breather can be used.\u003cbr data-mce-fragment=\"1\"\u003e Tech tip: The timing for S\u0026amp;S breather valves, only for late 77-84 Shovel and 84-99 Evo Big Twin models, has been changed by S\u0026amp;S in the year 2000.\u003cbr data-mce-fragment=\"1\"\u003e This is done to improve oil scavenging and reduce oil carry-over in high performance \/ large displacement engines.\u003cbr data-mce-fragment=\"1\"\u003e Old opening was at TDC and closing at 65° after BDC.  \u003cbr data-mce-fragment=\"1\"\u003eNew opening is 17° after TDC and closing at 82° after BDC.\u003cbr data-mce-fragment=\"1\"\u003e The old timing specification can be obtained by installing the timing mark on the breather gear one tooth clockwise from the timing mark on the cam gear.\u003cbr data-mce-fragment=\"1\"\u003e Also the breather's cavity oil evacuation hole (opposite of the drive gear), which used to be a round hole, has been elongated (made longer) to increase the duration of suction to the crankcase breather 'setting' cavity.\u003cbr data-mce-fragment=\"1\"\u003e The new specifications are not useful in most stock engines, but harmless.\u003cbr data-mce-fragment=\"1\"\u003e Breather windows in S\u0026amp;S cases will typically open at 7° after TDC and close 92° after BDC.\u003cbr data-mce-fragment=\"1\"\u003e Builders using other crankcases may modify crankcase breather opening to obtain these specifications for maximum breather efficiency and performance.\u003cbr data-mce-fragment=\"1\"\u003e OEM 25313-77A\u003cbr data-mce-fragment=\"1\"\u003e Fits: \u0026gt; L77-99 BT(EXCL. TC)","brand":"S\u0026S","offers":[{"title":"Default Title","offer_id":40423538229333,"sku":"MC970600","price":148.76,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1606\/2595\/products\/970600k.jpg?v=1668588361","url":"https:\/\/california-motorcycles.com\/en\/products\/s-s-steel-breather-valve-std-for-harley-davidson-2","provider":"California Motorcycles","version":"1.0","type":"link"}