Running a mower at full throttle ?

NIXON · Jul 23, 2004

My manual (and dealer ) say to run my rider at full throttle .
It (they ) say it's to aid in cooling . After running my mower for a few hours to get aquainted with it , it seems happier at about 80-90% throttle . ( less vibration and noise )
As long as I'm not loading the mower and engine , am I wrong to do this ? John

Molerj · Jul 23, 2004

Hi Prez /forums/images/graemlins/grin.gif, When mowing it is suggested full throttle for several reasons. The fins on the flywheel is what blows the air across the engine. Faster it turns the more air that blows thus cooling the engine. Also the blades will be turning faster, which ultimately gives you a better cut, especially in thicker/higher grass. That said, running it at 80-90% if it isn't under undo load won't hurt it.

GerardC · Jul 23, 2004

I have an MTD (SP) mower that has "no" throttle on it. You prime it, pull the starter cord, and she runs at full throttle all day long. G

Bird · Jul 23, 2004

( "no" throttle on it. You prime it, pull the starter cord, and she runs at full throttle all day long )

I think quite a few walk behind mowers are that way. Our Tecumseh powered LawnBoy is.

GerardC · Jul 23, 2004

That was new to me when I first saw it. Glad I bought it. G

froggy · Jul 24, 2004

I have always run my honda walkbehind mower at full throttle and have never had any problem. Would imagine the same would be said for a riding mower.

NIXON · Jul 24, 2004

Thanks for the responses ! At first glance running at full tilt seems a bit hard on the engine . But the fact that it's air cooled and benefits from the added air flow makes sense , John

Ledgemere Farm · Jul 25, 2004

Why do they do that? I always heard it was bad for an engine to shut it off at full throttle? /forums/images/graemlins/confused.gif

Bird · Jul 25, 2004

( always heard it was bad for an engine to shut it off at full throttle )

If an engine has a throttle, I always idle it down before shutting it off, and I've thought about that with this LawnBoy, but since there is no throttle, . . . , so far it hasn't seemed to hurt it. But it is something I've wondered about myself.

KubotaBling · Jul 25, 2004

It may make less noise but full throttle is best.. the gov. will control engine load responses when u run lower than rated speed the cylinder head tends to heat up due to more dwell time at tdc increasing the pressure and heat concentration same princable as lugging a diesel engine to put it clearly actualy most mowers are rated at 90% of there max. throttle in many makes the rpm is about 3250-3350 the maxium factory rating for that engine is 3600.. same with diesel's some are rated at 2500 rpm for fire work etc.. and the same engine might be rated at 2100 rpm another application..

Joe1 · Jul 25, 2004

"Full throtle" is really full Governed Speed. If you do not remove or modify the governor, then the engine is running at its optimum rpm for cooling and power output but not at the maximum rpm the engine could produce without a governor.

Joe

slammer · Jul 25, 2004

Yep. About 3500 rpm.

Slam

KubotaBling · Jul 26, 2004

yah full throttle rpm's can go as high as 5K from our test subjects /forums/images/graemlins/smile.gif 25hp v twin's.. not sure how long that'd last but they go that high.. i know on my 17hp vtwin kohler in my ford lgt it lasted about 3 months before it throwed the driveshaft u-joint..

Dave___in___CT · Jul 26, 2004

Hi...

...also.. check & keep the engine oil changed when it's recommended...

Dave...

slowrev · Jul 26, 2004

Bird,
The Lawnboy is 2 cycle right ? I believe they won't have the same issues as 4 cycle engines can with a "hard" shutdown.

Bird · Jul 26, 2004

( The Lawnboy is 2 cycle right ? )

In years past, when OMC (Outboard Marine Corp) owned Lawnboy, they were 2-cycle, but now they're made both ways. The one I'm using is a Tecumseh 4-cycle engine.

ThistleKop · Jul 26, 2004

When CPSC got in the business of regulating consumer lawn and garden equipment, a blade tip speed of 19,000fpm was established as the standard to control thrown objects. At that time the engine mfgrs. had to reduce the governed speed on their engines to comply. At the same time came the addition of guards, etc. In recent yrs. many other stds. have been added, eg., blade brakes, etc. This all resulted in safer but less user-friendly products and in many cases a product that does not perform its intended purpose as well.

TK