Metal-on-metal noise @ high RPM

Discussion in '2-Stroke Engines' started by ducky, Aug 7, 2007.

  1. ducky

    ducky Guest

    Hi all,

    I've been noticing for the past week or so a very unhealthy sound coming right from the engine. At high rpm it sounds like the piston is actually hitting something, or the components are loose inside or something to that effect. In any case it is definitely not normal. I took the head off and noticed I could rotate the piston slightly left or right, and in the up-down motion it seemed to have some play. There didn't seem to be any piston damage on the top, and there was absolutely no other visible damage on the cylinder or the piston itself. Just wondering if anyone else had any ideas? :( :confused:

    Thanks so much

    Ducky
     

  2. npk1977

    npk1977 Guest

    I wonder if there is any value in people recording their engine noises. Might help us diagnose these kinds of problems.
     
  3. azbill

    azbill Active Member

    it could be coming from the gears on right side of engine
    pull the cover and put some grease (about a navy-bean sized dab)right where the gears meet
     
  4. locoWelder

    locoWelder Guest

    Sounds like your wrist pin bushing might be shot
     
  5. ducky

    ducky Guest

    Thanks for the replies. locoWelder, is the wrist pin bushing part of what holds the cylinder on the crank? I could not find anything named as such in the crappy diagram the company gave me...

    Thanks again!
     
  6. rcjunkie

    rcjunkie Guest

    Second wrist pin bushing
     
  7. locoWelder

    locoWelder Guest

    The wrist pin bushing rides in the jurnal under the piston head , they are very easy to replace, and they do fail quite often in our little bundles of fun,Dax has a new needle bearing to replace the bushings I would recomend that you replace it even if its not the problem, this is just good maintainance.
    Just a small install note;take your connecting rod and put it in your frezer and the new needle bearing in your oven at home,heat the bearing to 300 and freze the rod over night use good gloves and a small bench press to install the bearing ,If you dont have a press use a c-clamp and some peices of plywood as a hand press to insert the bearing
     
  8. rcjunkie

    rcjunkie Guest

    I don't see roller bearings posted on Dax's website.
     
  9. ducky

    ducky Guest

    It turns out that yes, it is the bushing. I pulled the piston off the crank and ooh-la-la, the bushing was **** near cracked in half! Thanks so much for all the info. I will try to order a new one. bcmoped.com seems to be useless when it comes to parts.

    Thanks again!

    Ducky
     
  10. ducky

    ducky Guest

    As a follow-up, I'm having trouble finding a place to order parts in Canada :( Does anyone know where I might be able to order? You good ol' boys get all the good stuff ;)
     
  11. Dockspa1

    Dockspa1 Guest

    What version of motor do you have? Dac's, Kings, Simpson etc.
     
  12. srdavo

    srdavo Active Member

    Seems to me, freezing the connecting rod will make it smaller. (harder to press in the new bearing/bushing)
    Cold=Contracts
    Heat=Expands
    & I didn't have to completely remove my connecting rod to replace my bushing.


    Somebody also suggested using dry ice to shrink the bushing.
     
  13. ducky

    ducky Guest

    I have a King's motor. I'm certainly regretting it to some degree. Wish I had gone for Dac's or Simpson. But I live in the Great North. We don't seem to get everything as good in Canada :)
     
  14. dave1490

    dave1490 Guest



    ya that,s right heat the small hole in the rod and freeze the bearing.
     
  15. Patch

    Patch Guest

    My engine seems to be making the same metal on metal noise but all of the time. It still seems to run fine but very noisy...deafening almost! Its almost like a very strong vibration but ive inspect the all the parts i can without total dissassembly. So do you think my con rod to piston bushing is shot?

    I will go inspect right now PS I have a dax 70 has anyone else experienced this?
     
  16. srdavo

    srdavo Active Member

  17. Patch

    Patch Guest

    tHANKs Srdavo Unluckily that was the first thing I tried... Not a solution. This is much noisier It sounds like the piston is hitting something or something in the transmision is clicking but in a very loud metal clicking sort of way. To be more in-depth... Its a very resonant metal pinging/rattling sound. I could record it on video and post it somewhere?!?!
    And I have checked to wrist pin...seems to be fine
    Any other Ideas?
     
  18. Patch

    Patch Guest

    OK so Im swamped...my bushing looks fine, but I really don't know what a bad bushing looks like or feels like.

    The bushing does have some twisting room for motion but its pretty small. IE I can twist the piston head just a tiny bit...would that much matter?

    I don't have the guts to go in and check the crankshaft bushing :( but that too has a little room for movement which makes me think they're 'ok'

    Could someone show me what a just barely worn but inoperable bushing looks like? or just tell me if I should Post pictures of mine and start a new thread>? Any help much apreciated!
     
  19. ibeenjammin

    ibeenjammin Guest

    Hey Patch-

    I am having the same problem. I have recently had my motor apart and couldn't find anything wrong with my bushing as well. Have you noticed a loss in power, mainly lower end torque since you have been hearing the metal on metal noise? I am trying to problem solve for myself as well. I have lost a noticable amount of pull and I want it back. I would love to know if anyone has some input on when to replace the bushing as well. Obviously once it is shredded or cracked it needs to be replaced, but is their a way to tell if it has been worn too much and needs to be replaced? Thanks for all your help
     
  20. azvinnie

    azvinnie Guest

    i personally have had the lower bushing go, on me. which really means that you need a new bottom half. that is of course, if you know how to take these little engines apart with out hassle, ohh yaa puting back together without leaking(cracked case). still pains me, when l see it sitting on my bench:mad:
     
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