S&S Cycle 79cc Heads Supplement - Manual (Page 2)

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NOTE: There are two ways for the front S&S® 79cc head to breathe, through a vacuum port into the intake port or through the air cleaner. The position
of a set-screw must be moved to change the breathing format. S&S 79cc front heads are delivered for vacuum breathing into the intake port, with the set
screw installed in Hole 1.
1- As delivered, the S&S 79cc front head is set up for vacuum breathing with the set-screw positioned in Hole 1. The rear head can only breathe
through the air cleaner. This is the suggested breathing method for S&S 79cc heads. See Picture 1.
Picture 1
Hole 1
2- If you choose to set the front head to breathe through the air cleaner, move the set-screw from Hole 1 to Hole 2. See Picture 1 and torque it
to 20-36 in-lbs.
Hole 2
DANGER
WARNING
Do not run the S&S 79cc head with both Hole 1 and Hole 2 sealed. Also, Do not run the head with both Hole 1 and Hole 2 open.
3- Gaskets for the front and rear heads are identical—but must be installed so that the “J-shaped” channel is positioned towards the intake
manifold. (See Picture 1). This may cause one to be installed with the printed side facing up while the other is installed print side down. The
print on the gasket is not a factor in its function.
4- The gasket included with S&S 79cc heads measures .039”—which is .019” thicker than other S&S gaskets that measure .020”.
5- If you are using the stock air cleaner, the through hole in the two breather screws must be enlarged using a 9/64 (.1406”) diameter drill.
Do not use any other gasket than the supplied (2 Pack, PN 90-4120) .039” thick gasket on S&S 79cc heads.