Take a look at this, and tell me what you think

Discussion in 'Motorized Bicycle General Discussion' started by sellouma, Sep 12, 2010.

  1. sellouma

    sellouma New Member

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    Hello everyone,
    it has been a while I haven' t posted anything, but it's never too late.
    i have an OCC MB since Jan.2010 with almost 800 miles on it so far,I have been using it to go to work and i love it.
    I recently noticed that when i hit the gas, the engine starts vibrating a lot, like something is loose inside.
    i was riding my MB the other day, and suddenly the noise from the engine amplified, like as is I didn't have an exhaust pipe on it!!! i stopped to look at it and i found out that the pipe broke in half from all the vibration coming from the engine!! i had to go to work, so i rode it without a pipe, boy!!! that thing is LOUD like you can't imagine, and it got faster too!! good thing i didn't get arrested by the cops!
    I could see people turning their heads TWO blocks away to see what was coming up the street!
    anyway, i went home and decided to take a look at the engine to see if anything was loose inside the engine.
    so far i opened up the head cylinder, the cylinder and the piston, but I didn't like the way it looked
    (look at the color) and i noticed that the bottom ring is stuck , not like the top ring which spins freely, and I suspect that is what create the vibration when i try to increase the speed.
    I am going to take the engine apart(first time I am doing it and hopefully it is not going to be hard to reassemble) to make sure everything is in order.
    please take a look at the pictures and tell me what you think, any input is appreciated as it will help me get back on my usflg.
    Peace
     

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  2. bluenosegoat

    bluenosegoat New Member

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    I couldnt say for sure what the problem is but from the color of the piston below the rings I'd say your rings are shot. I've taken my engine apart after 2,000 miles and the bottom (below the rings ) is still all nice and shinny- no blow by. How was the power? Any noticeable decrease? I would think with bad rings power would be down due to loss in compression. Just a thought. I would ask Norm but since you have her torn down a new set of rings i would think is a must!
     
  3. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    It looks as though you been running it very rich, as in oil to gas ratio. What mixture and what type or brand of oil? Can't tell for sure but it looks as if the stuck ring could be just gummed up with burn't oil. Is that also rust I see in some of the pics? It really looks gummed up for that low of mileage.
     
  4. sellouma

    sellouma New Member

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    what about the piston? shall i keep it or get a new one?
    the power was good, but i noticed that if i give it more gas, the engine kind of hesitate , i can tell from the sound of it , but it 's not dramatic.
    When i rode my MB without the exhaust, it had a lot of torque and speed, i didn't have to even pedal at red lights, this thing just picks up and go!!.trk
     
  5. Nougat

    Nougat New Member

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    Riding without exhaust will burn up your motor, because there's nothing keeping he lubricating fuel/oil in the engine. Backpressure, in the correct amounts, is your friend.
     
  6. sellouma

    sellouma New Member

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    that is probably what caused the piston to look like that!!!
     
  7. sellouma

    sellouma New Member

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    you could be right about the rust, cause I left my MB outside in the rain for about a week!!!
    it just amazes me how it got there!!
    I used a motorcraft 2 stoke engine oil from the " Dome Hepot" store.
    the oil to gas ratio that i have used for the first time was 16:1 for about 2 galons and I switched to 24:1 as people were advicing in the forum.last month i switched to synthetic (see picture), i got it from the same store, oil to gas ratio is 50:1.
    I must say the engine became smoother and faster as started using 89 gasoline.
    now i am trying to open the bottom end of the engine to see if i need to replace the needle bearing in the shaft, but i can't unscrew the bolt whitout stripping it.(see picture).
    do i need to get rid of the rust that's in the crank or it doesn't affect the fonction of the engine?
    Cheers
     

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  8. r00t4rd3d

    r00t4rd3d New Member

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    A new jug and a piston/rings kit is cheap. If you got the extra money and you have it all apart already......

    I personally would not reuse any of that top end.
     
  9. sellouma

    sellouma New Member

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    new jug? u mean cylinder?
    i agree with you, i m going to replace them.
    any good quality parts or supplier you can recommend?(better than the stock that I have)
    thank you.
     
  10. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    And don't split the crankcase, there's no need to. The rust won't hurt anything but you should wash out the inside of the crankcase with solvent and then blow it out with compressed air. You were really running rich at some point....that spark plug says a lot, it's filthy.
     
  11. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    Me either. I think your best bet here would be to start from scratch with a new top end. May wanna replace that exhaust pipe too :)
    And you should be okay running on 87 octane. Shame that you'll have to start break-in procedures all over again, though.
     
  12. corgi1

    corgi1 New Member

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    is that plug dirt showing there is water in the gas?,,,,,and the piston should/must have a stop pin to keep the piston ring from spinning around
     
  13. Technocyclist

    Technocyclist Motorized Bicycle Senior Technologist

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    the stop pin could still be in the crankcase, if it did'nt blew out of the exhaust...
     
  14. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    That spark plug is showing signs of too much oil in the gas.....not water.
     
  15. Randog707

    Randog707 New Member

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    Hey Sellouma,I have a couple brand new pistons,that I have lying around for spare parts.PM me with your address and I'll send you one free of charge.I try help out my fellow MB'rs when I can,I've had my fair share of problems with theses bikes and got plenty of help from other members,so I try to pay it forward when I can.Randy
     
  16. Dan

    Dan Staff
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    .flg.Good man Randog. Really is a pleasure knowing MB folks. With the exception of "sales team", MB people just seem to be the same kinda nuts. Giving, fun and 'bout half a bubble off plumb but to the good.

    Made my day reading your post. Ayup, "pay it forward" My version of that is; "Repay a favor before it's owed"
     
  17. Randog707

    Randog707 New Member

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    Thanks Dan for your kind reply,I know it's hard in today's economy for us to just order new parts whenever our MB's breakdown which can be frequent!!,so if I have a part just lying around ,I'm the type of guy thats more than willing to help out the next man.The lord knows I've asked for my fair share of help,so I try to when I can.Randyusflg
     
    #17 Randog707, Sep 15, 2010
    Last edited: Sep 15, 2010

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