Tach for a 2 cycle?

Discussion in 'Mechanic and Repair' started by johnwon, May 31, 2007.

  1. johnwon

    johnwon LawnSite Senior Member
    Posts: 299

    Hi; I'm would like to know if one of those tachs made for a single cylinder 4 stroke gas engine would work on a 2 cycle engine and read the proper RPM's?? Thanks
     
  2. MarcSmith

    MarcSmith LawnSite Fanatic
    Posts: 7,157

  3. johnwon

    johnwon LawnSite Senior Member
    Posts: 299

    Thanks for the info. But what I'd still like to know is, will a tach made for a single cylinder 4 stroke gas engine read the correct RPM's on a single cylinder 2 cycle engine??
     
  4. MarcSmith

    MarcSmith LawnSite Fanatic
    Posts: 7,157

    no....most likely not....unless there is a switch on the back to change it from 4-2 stroke....Also depends on how the rpm info is fed into the tach as well...if it as being fed from the spark, then its going to receive a signal every ever other revolution for the 4 stroke and every revolution for the 2 stroke....

    it would work but it wont read correctly....
     
  5. pugs

    pugs LawnSite Gold Member
    Posts: 3,023

    Depends on the 4 cycle engine. Not all 4 cycle engines produce spark in the same manner.

    Most small air cooled 4 cycle engines produce a spark for every revolution of the flywheel similar to a 2cycle.

    However some older 4 cycle's with points only sparked half as many times.

    So it really depends on the engines you are comparing.
     
  6. johnwon

    johnwon LawnSite Senior Member
    Posts: 299

    Thanks for the insight
     

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