Need Factory Spec RPM Speeds Briggs and Stratton 9D902 (92000 series)


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I have a basic Murray 20 in mower with a Briggs and Stratton 9D902 3.5 HP 'Classic' L head (from 2000). It is a 'throttle free' model - ie. no throttle on the handle bar just down on the motor itself with 2 settings.

Lately the RPMs seemed kind of high so I checked it. In the low position it is 2,750 and in the high position it is 3,250. It runs good otherwise, smooth and strong. Just kinda fast - especially the idle. (using my finger I can manually push the vane/butterly closed and idle it down quite a bit)

I've looked at the owners manual for the 9D902 and found no specs on RPM speeds. I checked my old Briggs and Stratton repair manuals and only found 1,750 as a general idle speed for older 92000s. I did NOT find a high or governed or run RPM. I did find an RPM based on 20" blades WRT tip speed.

It's reasonably well maintained past 20 years.
  • Vane moves free and easy.
  • Oil changed annually and air filter cleaned, re-oiled.
  • Plug changed every couple/few years as needed.
  • Air vents blown clear as needed.
  • Several years ago, rebuilt carb and replaced primer bulb

QUESTION: Could someone with better B&S references that I have or can find, confirm what the idle and run RPMs should be for a 9D902 mounted on a 20 in. rotary mower?

Once I have a better idea of the idle and run RPMs - I'll play w/ reconfiguring the vane springs as needed to dial it in a little better. Thanks


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