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View Full Version : RPM of 21" push mower.


Alan0354
02-01-2010, 02:40 PM
Is there any reason to keep the rpm at about 3000 instead of increase it to vac better? What happen if you adjust to say 3600 to 4000, what would happen?

JimQ
02-01-2010, 04:24 PM
Is there any reason to keep the rpm at about 3000 instead of increase it to vac better? What happen if you adjust to say 3600 to 4000, what would happen?

Generally speaking, manufacturers keep 21" mowers at 3300 RPM. This puts the blade tip speed close to the 19K FPM ANSI limit. Try 3300 RPM.

Q

Alan0354
02-01-2010, 04:47 PM
Do I get better performance if set higher?

Valk
02-01-2010, 07:48 PM
You might. You will also be stressing more than just the blade...which is also designed for 19000fpm.

Rev it up, man!!

Alan0354
02-01-2010, 08:27 PM
I did it!! I had to mow 2' tall weeds!!!! I bend the governor up and mowed away, did not clog nor stopping the engine. I remember last time I did that with lower rpm, I had so much problem clogging inside.

It is a cheap mower, I can sharpen the blade again. All went well!!

Thanks:waving:

Valk
02-02-2010, 01:17 PM
On a side-note here and not intending to be beyond common sense:
My good ol' dealer semi-warned me about what added RPMs can do to an engine...especially an OLD engine. I'm sad to report that I think he's right.

I switched to a synthetic 2-stroke oil last year in the early Spring, and my old RedMax trimmer was prolly revving more, and more easily. It seemingly became underpowered by the heat of the Summer. So much so that I had to replace the old girl. RIP.

While I don't generally ever wish this on anybody, but, I hope your over-revving engine is expendable.

Alan0354
02-02-2010, 01:42 PM
While I don't generally ever wish this on anybody, but, I hope your over-revving engine is expendable.

It is!!! It is only a TroyBilt crappy mower, I can't wait for it to die!!! I won't use a good mower to mow 2' tall weeds, It was making all sort of strange chucking noise and I kept pushing it forward.

Anyway, it is all done and over. Both me and the mower survived!!!