1998 Zuma not running

Discussion in 'General Scooter Discussion' started by Paden Davis, Nov 3, 2020.

  1. Paden Davis

    Paden Davis New Member

    Messages:
    4
    Hey everyone, glad to be part of a forum! So I am having a problem, hopefully I am putting it in the correct thread. So I have a 1998 Yamaha Zuma CW50. Current upgrades are...
    70cc athena kit
    Upgrades springs and roller
    17mm carb
    Leo Vince exhaust
    No air filter
    Nology hot wire coil, upgrades variator..

    I think that’s it

    so first of all, this scooter is new to me, I purchased it from a guy who couldn’t figure out why it wouldn’t run, and I am having the same problem.. now I pretty mechanical, and am usually the guy my buddies call when they have issues, but I can’t figure this scooter out as to why it won’t start!
    Here is what I have checked so far

    Carb cleaned and fresh gas put in, def had plenty of compression, 120-130psi
    Has plenty of spark
    I checked vacuum fuel petcock to ensure proper operation, checked all hoses for leaks or cracks, they are good. Examined reeds for improper sealing, they are perfect. Took of exhaust and examined everything, put back on with new exhaust gasket. Checked spark against the head to ensure proper spark, and battery is brand new..

    Literally everything checks out

    fuel air spark compression, I’m assuming timing is correct as no one has ever messed with it, but I still can’t get this to start, even tried starting fluid in the cylinder and carb.. (I know I know, it was last resort)

    any help would be greatly appreciated!
     
  2. MARSH

    MARSH Whooooo!

    Messages:
    3,200
    Rides:
    Piaggio Typhoon
    Have you tried new spark plug ?
     
  3. Paden Davis

    Paden Davis New Member

    Messages:
    4
    Yes, spark plug is new, and has plenty of spark. Tried 2 different ones just to rule out a defect
     
  4. Stevep

    Stevep Well-Known Member

    Messages:
    5,895
    On cranking, is the plug staying dry or getting soaked?
     
  5. Paden Davis

    Paden Davis New Member

    Messages:
    4
    I wouldn’t say it is soaked, but it does have a drop of what I would assume to be gas on the bottom of it. If it weren’t getting enough gas to combust in cylinder, where would that lead me, carb is perfect, no issues at all and is as clean as you can get it without purchasing a new one
     
  6. Stevep

    Stevep Well-Known Member

    Messages:
    5,895
    Needle not raised enough blocking off the main jet hole???
    Wrong size needle maybe......length/width.....
    Any signs of oil leakage around the crank seals or crank case halves?
     
  7. Paden Davis

    Paden Davis New Member

    Messages:
    4
    No leaks and the needle has never been messed with. Crank seals seem fine, no oil or any issues that I can see, and I have looked at every thing. I did however try changing the reeds and changed the pilot jet to a bigger size, and I did get it to run for a short time with no exhaust on the head. I did order a new 70cc kit just to rule anything with the top end out, so I’ll see where that gets me
     

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