Zongshen 155z ho big problem

Discussion in 'Ask the Tech Masters???' started by foxman, Jun 23, 2012.

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  1. Jun 23, 2012 #1

    foxman

    foxman

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    Hi all,I have been on here ages ago asking probs with my engine,well 1 year later I'm still having it.
    To start with the motor didn't run right as it came with a Mollt carb,got a oko 26mm flat side and it still didn't run right,when I say didn't run right........basically spits fuel out of the carb into the oil filter,after mid throttle,changed the jets from 36-38 and 100-102-104 and no change muchly.
    So months on I had another crack at it and changed coil,cdi,plug and also stator and still spits out fuel.Valve clearance good and timing 12 0clock flywheel and 9 0clock on cam sprocket.has anyone had this prob and had something out of the ordinary that fixed it,the spark is really good too.Its just not sucking enough fuel down and spits it out.But when I bought it the motor actually was dropped on the floor from a forklift driver,maybe that did some damage somewhere that has caused this drama of a brand new engine never running right.Also when I took the flywheel cover off there was oil in there leaking from the stator plate,installed a new one and still leaks.
    Help would be awesome on this,I've have nearly chucked it into the ocean several times
     
  2. Jun 23, 2012 #2

    rotn50

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    might have a hairline fracture in the casing behind the magneto cover, is the keyway in one piece on the stator side of the crank?
     
  3. Jun 23, 2012 #3

    foxman

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    It's fine but I'm guessing that's not my issue with fuel spitting out,did a leak test and it's all good so I'm totally stuck
     
  4. Jun 23, 2012 #4

    DHZ_XR8cing

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    Is the crank case breather hose at the back of the engine blocked?? It could be pinched or kinked causing the oil leak.
    As for the fuel problem. Changing anything electrical wont change how the carbie works.
    What do you mean by spits fuel out the carb into the oil filter??
     
  5. Jun 23, 2012 #5

    GooseMan

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    think he mean air filter maybe.
    I know you said the timing is correct but it really sounds like it is out, or even your motor running backwards. Not sure if this happens with bikes but it has been known to happen with r/c engines.
     
  6. Jun 23, 2012 #6

    DHZ_XR8cing

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    You might be right Gooseman with saying air filter.
    Does the bike start?? You could have the timing 180 degrees out.
     
  7. Jun 23, 2012 #7

    foxman

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    Sorry I meant air filter,yes fuel spits out of the back of carb,yes it does start,like I said in my 1st post.....spits fuel out after mid throttle,tryed cdi and coil etc just to eliminate the problem,I have tryed molt,oko and even a 30mm mikuni and all do the same thing.How could I be 180 degrees out when I have the timing set to what it should be? Is 12 0clock and 9 0clock not a rule,I had another engine do this to me on my old yx150 and changed the stator and it fixed the problem.
     
  8. Jun 23, 2012 #8

    DHZ_XR8cing

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    So it runs I take it?
    You can have all your timing marks line up but be 180 out, By the sounds of it though because your bike runs this aint the case.
    Have you looked for a bent inlet valve??
    What carbie do you have on it at the moment? If its the oke try your clip on the middle slot and a 98 main jet.
     
  9. Jun 23, 2012 #9

    foxman

    foxman

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    i wondered about a bent valve too but the motor is brandnew remember,im running the oko at the moment,wouldnt runin a 98 main make it more leaner as it is?
     
  10. Jun 23, 2012 #10

    foxman

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    62677_10150685660614862_1787961241_n.jpg
    this is what ive put the engine in
     
  11. Jun 23, 2012 #11

    nickv1980

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    98 main is too small 100-102 range on a z155 with a 36-38 pilot

    I run 36 pilot 102 main

    To be honest mine will throw a mist of fuel back into the air filter when i rev it its just the nature of the motor / carbs
     
  12. Jun 24, 2012 #12

    foxman

    foxman

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    not the nature of this one though,like i said,after mid throttle nickv1980
     
  13. Jun 24, 2012 #13

    aussie_140

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    just get a new engine, you have already spent to much money trying to figure out the problem of a dud engine
     
  14. Jun 24, 2012 #14

    foxman

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    this cost me 1k in nz for this engine,cant afford to get another,i shouldnt have to since its a new one anyways! it hasnt cost me anything more for what ive tryed apart from time
     
  15. Jun 24, 2012 #15

    DHZ_XR8cing

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    Is the engine stock?? a 98 will be ok if it is. It will help you know if your problem is a jetting issue or not.

    I like the looks of your bike. Where will you ride that??
     
  16. Jun 24, 2012 #16

    rumble

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    Take the head off and have a look around. Will be a easy job with the engine in that position.
    Do a leak test on the valves.
    Also check the piston is at TDC with something down the spark plug hole.
     
  17. Jun 24, 2012 #17

    DHZ_XR8cing

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    If that engine cost you 1k and its doing that you should be taking it back to the shop.
     
  18. Jun 24, 2012 #18

    rotn50

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    Sick solo mate. there's a bloke here in townsville that runs a gpx 125 and the lifan 125 in his boys junior solo, even whacked a lifan 150 cam in the 125, the norm hate it when it beats the big coin kitacos.
     
  19. Jun 24, 2012 #19

    DHZ_XR8cing

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    Your's would throw a mist of fuel back because 102 on a stock engine is way to big.

    Try a 98 and see what it does.
    If it still does it then you know its not a jetting issue.
    Is the OKO a proper one or a copy??
     
  20. Jun 24, 2012 #20

    rotn50

    rotn50

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    Mate if that engine got dropped and oil got in the compression chamber and it got kicked over when new, that could bend a valve. Some fuel will always blow out the carby , but yours sounds extreme and just maybe a valve with it blowing compression and fuel thru the intake.
     

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