Grasshopper 322D-operating rpm

Discussion in 'Lawn Mowing' started by eltejano, Jun 6, 2007.

  1. eltejano

    eltejano LawnSite Member
    Posts: 2

    Greetings from East Texas

    I just joined the forum and I have a couple of questions. I just bought a new 2007 Grasshopper 322D with the 22hp Kubota engine and a 61" deck. I will be mowing for a couple of neighbors plus my own place - about 5 acres total with some hills. Mostly fertilized bahia, maintained at 3" and no collection system. I will be mulching leaves in the fall - bought the mulching kit with the mower.

    I have operated diesel engines all my life, in marine, automotive and tractor applications and I always been taught to run minimum rpm needed without lugging the engine. My dealer insists that I should ALWAYS run this 22hp engine wide open, all the time. But the mower has plenty of power at 3/4 throttle and the mowing is light duty - simply shaving an inch or two off thin bahia once a week - and the deck is 61, not 72. There's no tachometer - which I really miss - but I don't sense any lugging by ear, even at half throttle. Is there a reason for running it that fast? Wouldn't it just shorten engine life, burn more fuel and make more noise? Obviously if the bahia gets real high, or thick and/or I mow wet, then I'll punch it to max rpm.

    Secondly, I will be mulching dry oak/hickory leaves in the fall. Do I need to install those extra baffle plates that came with the kit, or is it enough to just install the plug on the discharge? Another set of blades came with it - I guess I should use those when mulching leaves? I will not be mulching grass clippings.

    Finally, there are protective "cones" over the bearings under the deck. If I wash the deck with the hose, water gets inside the cones - bad deal. That's the only thing I don't like - and the cones complicate blade changing too. The book says nothing about washing and recommends scraping the deck manually. Guess that's what I have to do, huh?

    Thanks. I appreciate your time

  2. TLS

    TLS LawnSite Fanatic
    Posts: 7,937

    I mow at FULL RPM's most all of the time. Only time I don't is when it's real dry and dusty and I'm mowing over bare dirt.

    They are designed to cut and discharge at full blade tip speed.

    Water is a mowers worst enemy. Underneath or on top of deck.

    Underneath the deck you should be OK if you don't direct the pressure washer at the spindle shafts. Remember, these decks are designed to mow in the rain. Water on TOP of the deck is usually worse.
  3. eltejano

    eltejano LawnSite Member
    Posts: 2

    Thank you for that, sir - even though it wasn't the answer I had hoped for. :rolleyes: That's what the dealer says too. I guess it has to do with mowing quality, though, and not necessarily the engine life.

    I use air to blow off the top of the deck but I've aways washed the underside - not on this one though.

    Appreciate your taking the time to answer me.

  4. Mowingman

    Mowingman LawnSite Platinum Member
    from Texas
    Posts: 4,662

    Run it wide open all the time when mowing. It needs the RPM's to the fan so it will cool properly.
    you can run just the cover plate with mulching blades, but you will get a windrow of mulched material along the right side each pass you make.
    Never wash under the deck, you are just asking to get water into a spindle bearing. However, the cone fits up behind a lip, plus, it has a hole in the bottom for the blade bolt. So, the chances are you will not get water in it, or, it will run out
  5. TLS

    TLS LawnSite Fanatic
    Posts: 7,937

    Biggest thing to remember when washing is to NEVER wash a warm mower.

    When everything is hot, then you wet it, then those hot parts cool and draw the moisture into the bearings, seals, etc.

    If your going to wash, do it when the mowers cool and just don't direct the pressure washer towards any "bad" areas.
  6. PLM-1

    PLM-1 LawnSite Bronze Member
    Posts: 1,640

    Run wide open for cooling reasons as said above. I wash my mowers all the time, everywhere. I then hotwax them at the car wash and it helps the nasty buildup. I grease them well afterwards to push the water out. The cones around the spindles are designed to keep debris from wrapping around the spindle, like sod netting. The baffles help alot with mulching. You may want the anti-blowout baffles to add to the leading edge of the deck as well.
  7. drducttape

    drducttape LawnSite Member
    from Justin
    Posts: 1

    Mowingman, drop me a line @, I'm looking for someone to do some work in Argyle.

    Sorry to hijack the forum..



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