A rattling sound coming from my engine? a little worried! Help!

Discussion in '2-Stroke Engines' started by StrontiumEthics, Oct 4, 2009.

  1. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    Im hearding a rattling sound comming from my engine. Im not to sure what the problems is. To be honest I wasnt really nice to this engine. At times I didnt really put a 20:1 ratio I would just mix by sense! I feel horrible now. But this last gas tank I mixed a 40:1 ratio. Anyone has any feelings what this noise is?? The next engine I get I WILL NOT EVER neglect!!
     

  2. arceeguy

    arceeguy Active Member

    If the noise changes when the clutch is engaged or not, then you have nothing to worry about. The clutch bearing design in these engines is known to be noisy. It is kind of a raspy random rattling at idle with the clutch disengaged. As soon as you release the clutch lever and hit the friction zone, the noise usually changes.

    However, if your rattling is precisely timed to engine RPM, you may have some issues with a connecting rod bearing.
     
  3. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    What can I do about this? Im not a pro at taking apart these engines though. I still heard the noise when I was riding at high rpms...I was wondering if I should increase the oil to fuel mixture ratio? Right now im running 36:1. By the way I usually never percisly measure the oil I put in. This is the first tank where I actually measured things out. Anywho, the noice is timed to the rpms i think. I was just checking it. What can I do? Its not REALLY loud, but its noticable. Someone told me that its probally the piston ring that is worn down?. From this engine on im treating SO much better!! I learned my lesson! I only had about 250 miles on it sofar. But it still pulls really hard though. No loss in performance, just that rattling sound!!
     
  4. Hawaii_Ed

    Hawaii_Ed Member

    Yup, I would grease the gears on the right side. Cover comes off easy (3 bolts I think). Mine started with some noise, tossed some axle grease on there and all is good now. It is a good idea to grease the gears on all new engines.

    40:1 sounds very lean to me, I still run 24:1 to be safe.
     
  5. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    I have a jackshaft kit, and tuned pipe.
     
  6. Skyliner70cc

    Skyliner70cc Active Member

    Don't worry about it and don't worry about the 20:1 oil ratio. You are doing more harm with using 20:1 than 40:1 with greater risk of stuck ring and carbon build up.

    As for the noise, I've got an engine that makes the most horrendous noise (rattles) at high rpms. It did it since new and that was almost 3 years ago. I tore it apart and never could figure out what the issue was.
     
  7. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    As for my new build im getting a new engine. So should I start the oil ratio at 32:1 or lower for the break in? Im going to reduce my current engine from 40:1 to 32:1 because I dont really use high quality oil. I use Castrol motor oil sometimes or 2 cycle oil from autozone.
     
  8. Victor Vance

    Victor Vance Member

    dose it sound like this? <object width="445" height="364"><param name="movie" value="http://www.youtube.com/v/H_h1z3e7UX0&hl=en&fs=1&rel=0&border=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/H_h1z3e7UX0&hl=en&fs=1&rel=0&border=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="445" height="364"></embed></object>
     
  9. bigdan

    bigdan Member

    Wow, What was that?
     
  10. Victor Vance

    Victor Vance Member

    the little cog thats on the crankshaft was loose.

    This was the culprit. I just tightened the bolt as was fixed.
     

    Attached Files:

  11. Skyliner70cc

    Skyliner70cc Active Member

    I loctite the bolt that holds it in.
     
  12. GCrews25

    GCrews25 New Member

    Victor, how exactly did you get to that gear to tighten that bolt down? I believe I'm having the same issue with the rattling noise at higher rpms. Hopefully that's it.
     
  13. Purple Haze

    Purple Haze Active Member

    One trick I've learned is to clearance the cover that holds the clutch lever. Every build I've done, the chain rubbed on the cover, making all sorts of weird noises. Easy to fix, simply remove the 3 screws that hold it on, no need to remove the clutch cable, rotate the clutch lever till it slides out, then take take your dremel (you do have one, right?) and grind or sand the place where it's rubbing. You don't have to remove much material, just enough to clearance the spot. You will see where it's rubbing, and it makes a HUGE difference in ridding your engine of all sorts of snaps, crackles, and pops.
     
  14. GCrews25

    GCrews25 New Member

    That might help, I'll look at that and see. Is also like to check that crankshaft bolt and see if that does the trick also.
    Thanks!
     
  15. Purple Haze

    Purple Haze Active Member

    While you're there, remove that crankshaft bolt (screw?) and put some blue loctite on it, then tighten it back up. They do have a habit of coming loose, I had one that got so loose the woodruff key between the gear and shaft came out, causing the gear to spin on the shaft.
     
  16. GCrews25

    GCrews25 New Member

    Sorry, not the most savvy with these yet. Awesome! Thank you
     
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