R/S engine knocking

Discussion in 'General Questions' started by mlcorson, Aug 2, 2009.

  1. mlcorson

    mlcorson Member

    I've got a new Robin Subaru EHO35 engine on a BMP friction drive. The engine likely has about 30 miles on it. Under load and at slower speed, typically accelerating, I hear a knocking in the engine. At higher speeds and cruising the knocking is NOT present. Is this just because its new? Gas is only a month or so old. Do I need to treat the gas? Or is this normal or something I can expect until broken in? Performance is good, at least for new engine.

  2. moped-dan

    moped-dan Guest

    I have the R/S engine too on a staton inc friction kit. I have a lot of knocking noises until I get going a decent speed (15 or so MPH). I think it maybe the clutch not engaging properly right away? Im not sure but youre not alone. Its not much of a problem in the country where I just cruise but its kind of a annoyance in the city because of the stop and go nature. Id love to solve this problem though it isnt a huge deal.

    By the way, the noise. The best way I can explain mine is when I throttle up while going under 15 or so I hear a sort of resonating grinder sound, going up and down in pitch. Its not a very violent sound but its definitly noticeable and is louder than the engine itself. The engine runs fine during this as far as I can tell but when I hit that magic speed it goes away and it sounds much quieter and smoother. How does this compare to what youre hearing?
    Last edited by a moderator: Aug 2, 2009
  3. srdavo

    srdavo Active Member

    here's a thought......
    check your drive roller bearings.

    when one of my bearings failed.... it would make noise during acceleration & low speeds.
  4. Zev0

    Zev0 Member

    It's the clutch! The noise will go away with use. Mine did the same thing when new, but quiet as a church mouse now.
  5. mlcorson

    mlcorson Member

    Maybe, but a long shot on a new drive system?
  6. moped-dan

    moped-dan Guest

    I thought bearings too.. but when riding with the engine off and drive roller engaged I hear none of the knocking noise. How long did the knocking last on your setup, Zev0
  7. Zev0

    Zev0 Member

    How long? Oh geeze, not sure, probably a couple of months. Maybe 100-150 miles.
  8. 5-7HEAVEN

    5-7HEAVEN Guest

    The sounds you are hearing are typically normal clutch/clutch bell noises when new, or replacing friction roller.

    It happened to me also.

    If it unsettles you, remove the engineand inspect the clutch, bell and clutch bellhousing for a broken clutch lever.

    Sometimes you'll hear a ting-ting-ringing sound when the engine clutch is new, sometimes a scraping noise.

    When in doubt, pull engine and check it out. It takes less than an hour.:detective: