Idle vibrstions...............

Discussion in '2-Stroke Engines' started by geebt48cc, Mar 21, 2010.

  1. geebt48cc

    geebt48cc Member

    :tt1: Everybody is always talking about bad vibrations with their bike motor. I've never had a problem at all. See, it's very smooth at idle, or at 30+mph.

    .............I guess from what I've gathered, 48cc is smoother.

  2. Dilly Bar Rob

    Dilly Bar Rob Member

    I think that part of this has to do with just how solid you can get the bike and all the mounting. Seems that anything that is not absolutely solid WILL add vibration somewhere in the RPM range. Last time I had a "un-identified vibe" it turned out to be the little heat shield on the muffler elbow, one of the screws that holds it on came loose, it weighs a few grams but it not being secure was all that it took. Something starts to vibrate and that passes vibration on to everything else, stuff starts to resonate, in turn loosening other screws causing even more vibration...

    I experimented with mounting the engine on my last bike on rubber (many here suggested it is a good idea, so I tried it), I think I actually did a really good job , but in the end it had WAY more vibration (at high rpm, low rpm was actually very smooth) then my two previous bikes with the engines mounted solid (and i do mean SOLID). I reverted back to solid mounting and BAM, vibes went away. For me solid just seems to work best.

    All three of my builds use "pk80" engines from zoombicycles, when new they do tend to vibrate a bit (my bottom would feel very uncomfortably tingly even after a short ride) but this seems to go away after break-in, must have something to do with those "tight factory tolerances" :)
  3. motorpsycho

    motorpsycho Active Member

    I don't know...i have a the 49 c.c. slant head, mounted to my frame with rubber.
    I have 0 vibrations at at idle or at any speed. it runs very smooth and does not vibrate the frame, handlebars or the seat.
    My friends 66 c.c. non slat head, is mounted solid to his frame, and it does not have any vibrations either.
    we both upgraded to higher quality nuts, bolts and washers to replace the ones that come with the kit, and we used blue loc-tite on every nut & bolt.
    so far 200 or so miles on each of our bikes, nothing has vibrated loose, nothing has fallen off, and both of our engines / bikes run very smooth with no vibrations.
  4. Hajuu

    Hajuu Member

    Yeah I think that mounting with rubber thing is kind of a 'seems like a good idea' things.

    I've mounted mine solid both times too, very low vibes. Only tasty motorized biking vibes!
  5. Dilly Bar Rob

    Dilly Bar Rob Member

    It's all about the "good vibes" :jester: