S&S, breather valve and steel spacer set. +.030" OD

With steel breather valve spacer set for correct axial play. Oversized +.030" steel breather valve. Used to salvage worn or damaged crankcases. Suitable for stock or high-performance replacement.
Note: JIMS has a +.030" breather hole cutter, available as 978343.
Note: S&S breather valves come with elongated breather holes to increase vacuum duration, allowing more oil to be drawn out of the cylinder heads. This has no disadvantage on any model year, either stock or Big Inch engine.
Technical tip: The S&S breather valve open/close timing, for late-model 77-99 Big Twins only, was changed by S&S in the year 2000. This is done to improve oil scavenging and reduce oil carry-over in high-performance/large-displacement engines. The old opening was at TDC and closing at 65° after BDC. The new opening is 17° after TDC and closing at 82° after BDC. 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 camshaft gear. Additionally, the oil drain hole in the breather cavity (opposite the drive gear), previously round, has been elongated (made longer) to increase the duration of suction to the crankcase breather 'settling' cavity. The new specifications are of no benefit in most stock engines, but are harmless. The breather windows in S&S crankcases typically open at 7° after TDC and close at 92° after BDC. Builders using other crankcases can modify the crankcase breather opening to achieve these specifications for maximum breather efficiency and performance.


Specifications


Brand
S&S


Application
L77-99 Big Twin (Excl. TC)


Sales unit
Kit


Material
Steel


Packaging weight
0.229 kg


HS Code
87141090


Motorcycle family
BIG TWIN, DYNA, FX, FXR, SOFTAIL, TOURING


Original name
S&S, steel breather valve & spacer set. +.030" OD