spark, new fule and compression wont start

Discussion in 'General Questions' started by Jake_the_potato, Jan 27, 2015.

  1. Jake_the_potato

    Jake_the_potato New Member

    i have fuel spark and compression plus the timing is spot on because its a brand new engine the what the **** could be wroung

  2. jaguar

    jaguar Well-Known Member

    under compression it takes more voltage to create a spark.
    so your out-of-the-engine test is not fully valid.
    make sure your spark gap is no more than 25 thou.
    clean the stator coil frame where the 4 screws seat onto it. that metal to metal contact is part of the ignition systems ground path.
    if still no spark then disconnect the stator coil from the cdi and test the coils voltage when you push the bike. should be art least 30 volts. if not then replace it.
  3. HeadSmess

    HeadSmess Well-Known Member

    chasing geese again.

    firstly...get an ngk plug.

    then start of with the basics and find out WHAT THE PROBLEM IS systematically.

    so, it has spark. we think so, we can see it. doesnt really mean doodly squat :) it the timing, or is it to tell?

    by removing the carb, pouring a few cc of fuel down the intake, and giving it a go.

    if it starts, you have determined that the problem is a fuel issue, so look inside the carb etc.

    if it does not start, well...then it must be an ignition or compression issue.

    having figured out which way to go, you can then search for help on whatever area you KNOW is being a problem :)

    of course, this is assuming everything else is correctly setup, and it isnt clutch slip or something similarly silly.

    dont assume that if its new that its right...

    theres posts on here of reverse magnetised magnetos, and also backwards wired cdi's...

    the missing key behind the magnet is pretty common, and the occasional bad earth to a head pops up... always check the plug on the head, the bit it bolts to and earths through ;) crankcase can be deceiving...

    carbs come with badly adjusted floats, blocked jets, black bits of unknown stuff in the bowl, etc etc etc...