Engine System
25
Service Manual – PBU Propane Floor Burnisher
Throttle High Idle Position
This adjustment sets the upper limit of the Throttle Position Link Arm, which indirectly controls the high
idle speed of the engine via the governor This adjustment may be completed on its own, or as a followup
adjustment to adjusting the fuel mixture described on page 26
1 Start the engine and bring it up to operating
temperature
2 Make sure the burnishing pad is raised so
there is no load on the engine
3 Move the throttle selector to Fast
4 Loosen the jamb nut and adjust the high limit
screw until the engine tachometer reads the
correct engine speed listed below Loosen the
screw to increase speed, or tighten the screw
to decrease speed
• 21” machines: 3400 to 3450 rpm
• 27” machines: 3450 to 3550 rpm
5 Retighten the jamb nut
Carburetor Low Idle
Unlike the High Idle Position that indirectly controls the engine RPM via the governor, the Low Idle
adjustment acts directly on the carburetor butterfly valve to set the minimum butterfly position for engine
idle This adjustment may be completed on its own, or as a followup adjustment to adjusting the fuel mixture
described on page 26
described on page 24 is correct
2 Start the engine and bring it up to operating
temperature
3 Make sure the burnishing pad is raised so
there is no load on the engine
4 Move the throttle selector to Slow
5 Adjust the Low Idle adjustment screw until
the engine idles at 1800 to 2000 rpm Loosen
the screw to decrease the rpm, or tighten the
screw to increase the rpm
Throttle Position
Link Arm
High Limit
Screw
Jamb Nut
Low Idle
Screw
Butterfly Valve
Linkage
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