RPM of 21" push mower.

Discussion in 'Lawn Mowing' started by Alan0354, Feb 1, 2010.

  1. Alan0354

    Alan0354 LawnSite Platinum Member
    Posts: 4,458

    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?
     
  2. JimQ

    JimQ LawnSite Bronze Member
    Posts: 1,139

    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
     
  3. Alan0354

    Alan0354 LawnSite Platinum Member
    Posts: 4,458

    Do I get better performance if set higher?
     
  4. Valk

    Valk LawnSite Silver Member
    Posts: 2,711

    You might. You will also be stressing more than just the blade...which is also designed for 19000fpm.

    Rev it up, man!!
     
  5. Alan0354

    Alan0354 LawnSite Platinum Member
    Posts: 4,458

    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:
     
  6. Valk

    Valk LawnSite Silver Member
    Posts: 2,711

    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.
     
  7. Alan0354

    Alan0354 LawnSite Platinum Member
    Posts: 4,458

    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!!!
     

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