Engine swap on a Scag walkbehind

Discussion in 'Mechanic and Repair' started by crawdad, Feb 25, 2004.

  1. crawdad

    crawdad LawnSite Bronze Member
    Messages: 1,938

    Scag walkbehind, 48", currently running a 17 Kaw. I want to swap the engine, might as well go to a larger one. A 19 or 21. Would a 21 be too heavy? What's the weight difference, anyone know? Any other bad points to going so big? It's only 200 bucks more than the 19 hp.
    17 hp $1069
    19 hp $1269
    21 hp $1469
  2. crawdad

    crawdad LawnSite Bronze Member
    Messages: 1,938

    I just noticed, I put this in the elements of business section. I usually go through "view new posts", not individual sections. Sorry, folks.
    Please move to the appropriate forum for me.
    Mechanic and Repair
  3. GreenTurf

    GreenTurf LawnSite Member
    from NJ
    Messages: 41


    just curious how the 17 hp engine performed. did it bog down. how was it maintenance wise. I got an old exmark i rebuilt and it had a 12 1/2 horse kawasaki and I was thinking of putting a 17 on it. gonna be used for back up mostly
  4. crawdad

    crawdad LawnSite Bronze Member
    Messages: 1,938

    It performed pretty well. On the third of July, I had some problems, first serious downtime, and my dealer's mechanics got me going the same day.
    But, they said, it may last 15 minutes or 15 years. I put a bunch of hours on it after that. Starting to smoke a bit. I don't want downtime this year. Rather than rebuild, I say replace, although it has less than a thousand hours.
  5. Cut This!

    Cut This! LawnSite Member
    Messages: 48


    Weights of the Kawasaki's are;
    15hp 70.5#
    17hp 71#
    19Hp 71.2#
    21Hp 88#

    All are listed as dry weight, less muffler.

    You won't have a problem with the extra weight.
  6. swim

    swim LawnSite Senior Member
    Messages: 357

    Crawdad when pricing new mowers the dealer said that the frame size changes between the 17hp and the 20hp models.

    Not sure that it really matters but the bigger frames and engines may have heavier duty parts as well. This may cause more break downs than it prevents if that is correct.

    I know if you can aford the new engine it will be less likely to break down than rebuilding, but I have overhauled mine for about $300 or $400 in parts in the winter.
  7. crawdad

    crawdad LawnSite Bronze Member
    Messages: 1,938

    They said at the dealer that the frame may need some new holes for mounting a larger engine. I'd guess that the 19 would bolt right on, seeing the .2# weight difference.

    I figured the weight would be close, sometimes the only difference in different hp engines is a small carb change or a heavier flywheel. Winter is about over (although we are under a winter storm watch now, got a big-un on the way) and I am unsure of rebuilding myself, maybe I'll get a price from the dealer.
  8. Shultz

    Shultz LawnSite Member
    Messages: 83

    I'd bet there is no difference in the block size, but you could check. On the 22 and 27 lc, the block is the same.
    Will you notice the 2 hp increase?
  9. crawdad

    crawdad LawnSite Bronze Member
    Messages: 1,938

    I'd say I'll likely notice it on hills, and that's why I was thinking of an extra 4 instead of just 2.
  10. Shultz

    Shultz LawnSite Member
    Messages: 83

    the hp curve difference isnt as big as I would have thought, but the torque curve difference is huge....

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