Is premium fule neccessary?

Discussion in '4-Stroke Engines' started by Norm, Jun 1, 2008.

  1. Norm

    Norm Member

    Is there any way to tell if your motor likes premium better than reg unleaded?

  2. HoughMade

    HoughMade Guest

    Mine runs fine on 87 octane. What does the owner's manual say? If an engine is not designed to take advantage of higher octane, it will not help anything (may even reduce power to run on higher) and, that I know of, these small engines are all built to run run on regular.
  3. fetor56

    fetor56 Guest

    I doubt if u would notice any difference in performance between the lowest & highest octane levels....not enough anyway to justify the price increase.
  4. arceeguy

    arceeguy Active Member

    Most small utility engines are designed to tolerate crappy fuel. They have (relatively) low compression and tame ignition timing. This allows them to run properly on fuel that has degraded quite a bit from storage.

    This also allows quite a bit of performance gain if you raise compression ratios and advance the ignition timing. (Briggs, Tecumseh and Honda kart engines are a good example)
  5. Irish John

    Irish John Guest

    Sounds interesting. How do you raise compression and advance the timing on a Honda GXH or Huangsheng copy? Are there drawbacks?
  6. darwin

    darwin Well-Known Member

    If its a true cart engine then were talking apples and oranges here, cart engines cost in the thousands of $$$$ and are not weedwhacker motors.
  7. darwin

    darwin Well-Known Member

    I was thinking of those lil formula cars that go like a bat out of **** around the race tracks.
  8. HoughMade

    HoughMade Guest

    Well, a Honda GXH50 ain't a weed wacker motor- generator, perhaps.

    To advance timing would take an offset flywheel key and to raise compression would either require a new, taller piston (not likely to find), or you need to machine the head.
  9. MasterLink

    MasterLink Member

    i cant tell any difference the manual says 87
  10. Mountainman

    Mountainman Active Member

    Subaru regarding the Robin says to burn -- REGULAR GAS -- most of the small engines I have used over the years have called for the same. Happy Riding from - Mountainman