Proper engine speed zero turn motor
- Thread starter oldcodger
- Start date
Wide open or close to it. You need enough RPM to spin the blades fast enough for your conditions and enough to propel the mower. I keep mine a hair below max and it does fine and saves some fuel. I believe the max setting is not true max to save the motor.
Most of the OPE engines create rated HP at 3600RPM. I recently adjusted the governor on my JD235 to 3600, per the manual. It was down to 2800! Most likely due to the governor spring rusting and getting weak. I don't often need to run the eng at full RPM, but it's nice to have when mulching leaves, as it does a much better job.
NOTE: I think this thread belongs in the Lawn Mower section, not Motorcycle.
NOTE: I think this thread belongs in the Lawn Mower section, not Motorcycle.
Last edited:
Propflux01
$100 Site Donor 2026
I would think this applies to a dual-blade Zero Turn as well. If you have a 42" mower with 2 21" blades, 3,274 RPM would be your speed.
Blade tip speed (in Feet Per Minute) is calculated by multiplying the engine RPM by π (approximately 3.1415) and the blade length (in inches), then dividing by 12.
(Based on maintaining the standard 18,000 FPM target)
Blade tip speed (in Feet Per Minute) is calculated by multiplying the engine RPM by π (approximately 3.1415) and the blade length (in inches), then dividing by 12.
(Based on maintaining the standard 18,000 FPM target)
dnewton3
Staff member
Correct; 3600 rpm is the commonly designed operating speed for most any OPE engine.
thread moved
How exactly do you go about adjusting the governor? I need to put a tach on my John deere zero turn. Cut quality has always been poor even with new/sharp blades and all I can figure is lack of blade speed. Engine sounds normal. Briggs 22hp
3600 RPM is usually the rated speed for air-cooled outdoor power equipment engines, and they should be run at full throttle when under load for optimal cooling.
The answer is in the manual. Check the manual from the mfg. RTFM
My Toro ZTM manual says max throttle when cutting. My previous Hustler ZTM said the same.
My Toro also says in the manual, and also a sticker next to the throttle, to go max throttle then turn the key off to shut down.
My Toro also says in the manual, and also a sticker next to the throttle, to go max throttle then turn the key off to shut down.
It all depends on the application. Something I've learned is that while you'll see 3600 RPM in the manuals that is usually what speed they use for HP testing only & not the actual setting on the mower. The mower manufacturer may have a different plan & set your engine at 3400 RPM or in the Simplicity I just bought the HP rating of 30HP was at 3,200 RPM. 3,600 is usually "Max" for a small engine but that may not get you the longest lifespan. Performance wise it's nice to bump it up closer to that RPM though.
Just reread your post
You should always use full throttle under load. It would help to tell us what you have or find out what the manual shows.
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