Low Hanging Shrubs Effecting RPM's

[Lawn-Boy Rocky]

:laughing:
Does anybody else have this problem?
When trimming around large leafy plants and/or shrubs which seem to restrict the air flow through the top fan screen, the air vane governor temporarily spins the RPM's way-up? Maybe this is an inherent issue with open topped Lawn-Boy motors?
It's a little unnerving at times.
Rocky

 

[TorqueMonster]

I’m thinking that what is happening is Not because of the big leaves on top of the motor. I believe this is what’s happening. When you’re mowing and you are pushing the mower into plants, scrubs etc one of the limbs of the plant is hitting the air vane causing the motor to rev.

I understand what’s happening and I will try to explain it, But certainly if I’m not doing it justice please someone else jump in. When the motor is running and not under a load the air vane remains a certain distance from the flywheel so there is a steady supply of fuel and the motor runs at a consistent/steady rpm. When the motor starts cutting in high grass (now the motor is under a load) the flywheel slows down spinning, this means the air vane moves closer to the flywheel which then sends more fuel to the motor to get the rpms back up where they were when it wasn’t under a load.

SO, when you’re mowing and you push the mower into a limb (and you probably don’t even know this is happening) the limb pushes the air vane close to the flywheel Which sends more fuel to the motor. BUT since the motor isn’t under a load it REALLY revs up.

Hopefully I helped out. And if I’m wrong please someone correct me. Thanks, Mark

 

[bertsmobile1]

This happens with all push mower except Honda's & Victa's .
All B & S powered mowers have the throttle way out front which gets snagged or even bent by low shrubs.

Honda tuck theirs behind the filter well out of the way
Victa run the throttle cable through the snorkel tube & govern by air flow under the deck.

 

[Lawn-Boy Rocky]

I appreciate everybody's theories, but it happened without any physical contact with any throttle linkage contact.
Large leaves seem to smother the air flow into the top screen and across the air vane, so it speeds up.
What do you all think about that idea?
Rocky

 

[bertsmobile1]

You can test the theory with a sheet of paper.
I doubt you will be able to replicate the results until the screen is completely bloked.
Try raking out under the shrubs first and see if you get the same results

 

[Lawn-Boy Rocky]

:smile:Exactly, the paper will stop the air flow and "fake out" the air vane throttle (thinking it's suddenly in thick grass) and increase the engine speed.
Thanks,
Rocky