Engine Trouble loud rattling from lower engine

Discussion in '2-Stroke Engines' started by abtexas83, Oct 3, 2013.

  1. abtexas83

    abtexas83 New Member

    So I just got past the break in stage of my 66cc. This is my first post so please bare with me. But at high rpm I get a crazy high frequency metal rattling noise, Almost consistent with the cheap metal fenders vibrating. But I removed those and pinned it down to the left and right of the lower engine. Its pretty loud so I cant judge if its more on one side then the other. It does this with clutch engaged and not, but it will NOT make this noise when pulling up a hill. It runs solid just crazy annoying at higher rpms.

  2. Fabian

    Fabian Well-Known Member

    Just how high is high rpm?
  3. abtexas83

    abtexas83 New Member


    Half throttle, 15-20 mph. I don't know exact rpms
  4. crassius

    crassius Well-Known Member

    many of these have a really annoying clutch squeal - never found a good way to deal with that
  5. abtexas83

    abtexas83 New Member

    So I have narrowed it down to the chain. With the bike parked I reved it up and simply laid my foot on the chain. This removed the noise. But it seems that would make the chain to tight.
  6. HeadSmess

    HeadSmess Well-Known Member

    some chains are worse than anchor chain. oil or replace.

    theres too much slack between pinion and clutch gear...they always rattle.

    some gears are machined all wonky. better luck next time :jester:

    some bearings are bordering on failure from the word go...replace :)

    the clutch gear "floats" in midair. theres bearings in there but they rarely actually contact.

    the engines are just plain noisy anyway... its hard to say whats normal and what isnt without having used a few...
  7. Big Red

    Big Red Active Member

    HeadSmess pretty much said it all, I GOT NOTHIN:jester: