1. Missed the live Ask the Expert event?
    Catch up on the conversation with Ken Hutcheson, President of U.S. Lawns, in the Franchising forum.

    Dismiss Notice

Toro 21 2 cycle RPM increase

Discussion in 'Mechanic and Repair' started by tsinteto, Sep 8, 2004.

  1. tsinteto

    tsinteto LawnSite Member
    Messages: 2

    I am trying to in crease the RPM of my 2 cycle BBC. With the blade engaged it only does 2900 RPM. I don't have a manual(a homeowner was throwing it out) and the screw I turned increased the speed but without the blade engaged it would continue to increase above 3600 rpm and it did not increase RPM with the blade engaged. Also what is the RPM limit of this engine?
  2. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    It will blow at about 8000 - 8500 rpms but takes a few minutes.

    There are a couple of holes in the governor arm. First, move the governor spring to the top hole. If you don't get the rpm's you want, then, drill another hole higher up on the governor arm. Do not attempt or try or even think about shortening the governor spring. Leave that to an experienced technician.

    For a view of the engine go to Toro.com

  3. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    You can go to https://lookup2.toro.com and have them mail you a new owners manual. There have parts look up on line but few manuals, I just checked.
  4. tsinteto

    tsinteto LawnSite Member
    Messages: 2

    Thanks Gentlemen!!!
  5. OldLawnMowerMan81

    OldLawnMowerMan81 LawnSite Member
    Messages: 66

    Apologies since this is an old post, but, I'd say 2900 is right around there (check if the spring is mounted in the center or bottom hole). The center hole should amount to 3000 with the blade engaged.

    The top hole will increase the speed to 3150 RPM, and the bottom hole will bring the speed down to 2850 RPM (again, 2900 is what you said), and those figures apply with the blade engaged.

    Without the blade engaged, the respective figures by governor spring position are approximately:
    3450 RPM (w/ spring in top hole)
    3300 RPM (w/ spring in center hole)
    3150 RPM (w/ spring in bottom hole)

    More info can be found here:
    http://ourfamilys.deandrea.net/BobKitty/User Guides/togts120.pdf
    (yes, the engine covered here is older than yours, but the governor operation would be the same)


Share This Page