It's a Mystery - Recoil rips out your hand !!

Discussion in 'Mechanic and Repair' started by rob7233, May 19, 2010.

  1. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Mechanics, like doctors and lawyers and accountants , all think they're right.

    Has the rope snatched out of your mechanics hand? If your mechanic is as good as you think he is, Im sure he checked the valve adjustments. It doesn't take long to call roll.....there are only so many things that cause an engine to kick back. The ACR may operate when slowly turning the engine, but its not working when you yank it.

    Change the cam...that dog will bite you.
  2. rob7233

    rob7233 LawnSite Senior Member
    Messages: 876

    Okay, I'm buying. :drinkup: Yeah, I'm stubborn. But I have found a time too many (and to my benefit), that conventional wisdom is almost always wrong..

    No, it hasn't torned out of this mechanic's hand but it has in another's.

    Yes, valve adjustment is spot on.

    You said there are so many reasons for an engine to kick back....

    Would you list them? - And do those reasons include causes for engines w/o an ACR?

    Thanks for your response!
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Rob Rob Rob...... I don't know how long piston slapper has been spinnin wrenches but I've been at it over 30 yrs dude......

    Sounds to me you have a bunch of idiots working on your unit, Last I heard there's no one on earth that has X-ray vision. So how tha he11 can they KNOW the ACR is working properly under ALL cranking speeds ???

    If they have done all you have posted, REPLACE the dam cam and be done with it !!!

    Better yet, Load it up and drive 155.43 miles NW and I'll fix the thing....

    OR, Take Kawi's advise and "PULL HARDER" !!! Thumbs Up
  4. mikes landscaping

    mikes landscaping LawnSite Senior Member
    from kansas
    Messages: 298

    I have the same engine one a ferris wb and it does that. I haven't even bothered to fix it
    Posted via Mobile Device
  5. carlriv

    carlriv LawnSite Member
    from Mass
    Messages: 99

    Whats a cam replacement cost on a 14 year old engine??? $300 - $400?? Whats a new engine cost? $700 and get quite a few years of trouble free service.... How about stitches, pulled tendons or a broken bone?
  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Round $250 parts and labor......

    New engine $800 +
  7. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,141

    Try tightening the valve clearance. Make sure there is some clearance and pull it slow at first, to make sure there are no interference problems That will open the valve more during starting. If it helps, it's got to be the ACR. Take all parasitic loads off the engine also during testing.
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Rob7233 ....Here,s how it more time...without the muzzle or the dog...

    Check the valves and the ACR bump during compression stroke
    Pull the rope ...if it kicksback ...check the flywheel key
    If it still kicksback, disconnect the sparkplug wire...pull rope again
    Now you have eliminated any flywheel or ignition issues..
    If it still kickback, your problem is internal ...
    Either the ACR isnt working properly...
    The cam is 1 tooth off..either from the factory or it jumped time..
    On this engine,the crank gear also has a halfmoon key that might be damaged

    When you remove the engine sump check the timing before you remove the cam.

    Its cheaper to muzzle the dog (fix the problem)
    Than to pay for the bite(damaging your arm or hand)
    I hope thats not too cryptic.....
  9. rob7233

    rob7233 LawnSite Senior Member
    Messages: 876

    Thanks for all the replies and input.

    This engine doesn't kick back all the time but just once in a while (maybe on the compression stroke?).

    The piece(s) of info I was looking for was:

    " - If exhaust valve does not open more than 0.06mm (0.024in) briefly just after intake valve closes, ACR mechanism on camshaft is faulty."

    If the highest compression reading is less than 71psi, I'll need to trouble shoot the engine.
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Change the cam before someboby else gets hurt.


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