Installing Part #21612 Exhaust Valve Seat Insert - Briggs & Stratton Twin Cylinder L-Head Repair Manual

Installing Part #21612 Exhaust
Valve Seat Insert
1. Modify Tool #19131 counterbore cutter as shown,
Fig. 27.
2. With old valve seat insert removed, install pilot
Tool #19127 into exhaust valve guide.
3. Assemble Tool #19131 counterbore cutter to Tool
#19129 shank.
4. Counterbore the cylinder by hand until the stop on
cutter touches cylinder, Fig. 28. Do not force the
counterbore to one side or it will cut oversize.
a. Lubricate with Stanisol or kerosene.
5. Remove all chips.
6. Place drive pilot, Tool #19127, in valve guide.
7. Place #21612 insert on seat counterbore with
radius down. Use old insert as a spacer between
new seat and insert driver, Tool #19136.
8. Drive seat insert in until it bottoms, Fig. 29.
9. Peen new seat insert, Fig. 30.
10
5
Fig. 27 – Modify Tool #19131
#19131
CUTTER
STOP
Fig. 28 – Counterboring for Valve Seat
PILOT
#19127
Fig. 29 – Install Valve Seat
USE CENTER PUNCH
TO TIGHTEN INSERT AT
THREE POINTS
EQUALLY SPACED.
Fig. 30 – Peening Valve Seat
INCREASE
CUTTER
STOP
DEPTH
.030
CAREFULLY
DRIVE
WITH BRASS
ROD
#19129
CUTTER SHANK
CUTTER
PILOT
DRIVER
#19136
#21612
VALVE
SEAT
PEEN OVER EDGE
AROUND ENTIRE
INSERT.
METAL
SQUEEZED
AGAINST
INSERT