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Does anyone know what the differences are between a home owner engine and a commercial engine ? The only thing I see is a better air filtration system on the commercials.
Do they have better bearings or larger engines or what ?
I have always wondered about this.
Jerry

home owner engines are designed to do 50 hours a season
Commercial engines are designed to do 50 hours a week.
On some there is next to no difference on others there is a works of difference like one having a malleable iron crank & the other a forged steel one.
You really need to specify which engines.
No mower engine has bearings any more.I think Onan was the last maker to do this and it sent them broke because people will not pay for quality .

bertsmobile1 said:

...No mower engine has bearings any more....

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Actually, Kawasaki still does.

ALL engines have bearings. The questions are: Which type ? And, what are they made of ?

Born2Mow said:

ALL engines have bearings. The questions are: Which type ? And, what are they made of ?

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Actually they don't HAVE bearings
They have bearing SURFACES but that is a different thing to HAVING a bearing .
But if it makes you any happier
To cut costs mower engines manufacturers no longer fit replaceable bearings or bushes and simply machine the Al-Si-Cu cases to act as a bush
Al-Si-Cu is a 3rd rate bushing material so any wear or partial seizure is very likely to render the entire engine junk .
BEcause of the propentency of Al to weld onto steel that makes the engine much more sensitive to low oil situations and in particular make them very likely to seize due to low oil when used on a slope, some thing that an engine with real ROLLING ELEMENT bearings would be affected by.

Top quality commercial mowers use horizontal crank engines that have a deeper sump so con run on substantially steeper slopes without damage .
Not a problem if you live on dead flat land.
My workshop is in the foot hills and just about very engine I split has substantial wear to the upper bushing surface
I have put in real bushes made from 85:5:5:5 to save the larger expensive to replace engines but the push mower engines just get replaced.
It is about the only used mowers I sell now days, old 2 strokes to people with lawns too steep for modern 4 stroke engines .
The old Sprit engines seem to be able to handle slopes but the new OHV engines can die in less than season.

Bearings are expensive, bushings are cheaper, running a cast crank/cam on an aluminum cast bore is free. I've read there are some Suzuki verticals that do have bearings on the cranks, from their old 2 stroke origins I suspect.

tom3 said:

Bearings are expensive, bushings are cheaper, running a cast crank/cam on an aluminum cast bore is free. I've read there are some Suzuki verticals that do have bearings on the cranks, from their old 2 stroke origins I suspect.

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ActuallyTom, there is not much difference in the price between a rolling element bearing and a bush in these applications by the time they are fitted.
Rolling element bearings now days are very cheap so there is little excuse for not fitting them to the top & bottom of the crank.
Remember he journals have to be ground very accurately to run directly on the case where as they can just be machined if a bearing is going to be fitted .silicide
Add to that the microstructure of Al casting alloys is diamond hard crystals of silicide around the grain boundries of the soft alpha phase aluminium.
This is 100% the opposite of what you want in a bushing surface where you are looking for very soft particles embedded in a stiffer matrix
If you are confused then look up the microstructure of a Babbit alloy then compare it to that of an aluminium casting alloy

goes to show how cheap ball bearings are, HF predator engine cranks are supported by 2 ball bearings, PTO side and flywheel side.
But it's probably the bearings are made cheaper too.

Scrubcadet10 said:

goes to show how cheap ball bearings are, HF predator engine cranks are supported by 2 ball bearings, PTO side and flywheel side.
But it's probably the bearings are made cheaper too.

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That is because they are copied from the Honda engine which was built properly but became too expensive for tight fisted mower buyers.
Onans have balls and so do Generacs both of which got dropped .

If you are making an engine and you want to make more because you are selling them at a low profit margin then you make then frail .
So you use the crank case for bushing knowing that if the owner runs them on a slop or if they allow to oil to drop then the engine will seize but the owner will blame themselves and replace the engine .

I was working on Honda engines in the early 1970's that ran the camshaft(s) directly in the aluminum head or cover. Those never gave any trouble until you ran low on oil or missed an oil change.

Born2Mow said:

I was working on Honda engines in the early 1970's that ran the camshaft(s) directly in the aluminum head or cover. Those never gave any trouble until you ran low on oil or missed an oil change.

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Exactly the point, ran fine unless you ran low in water or oil or missed an oil change , so you end up blaming yourself for the trashed head .
Where as a rolling element bearing or gunmetal bush would not have been affected any where near as much.
The rolling element bearing would have run till after there was not enough oil to float the big ends without problems .

Back when the Briggs 5hp was THE engine for WKA stock engine class some guys bought the 130212 engine with the bushed PTO side crank bearing instead of the 130232 engine which had the ball bearing on the PTO side of the crank because it was cheaper. Geared properly the engines topped out at 6000 rpm. In one day of racing they could egg out the bearing surface in the case from the side load of the chain. I wouldn't build the 130212 engines for guys because they wouldn't last. The 130232 would last a whole season if you double bushes the valve guides. The crank was never a problem with them.