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Louie
Louie, Technician
Category: Motorcycle
Satisfied Customers: 11430
Experience:  25+ yrs. experience
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My bike won't start...brand new fully charged battery,

Customer Question

My bike won't start...brand new fully charged battery, starter motor, starter relay, stator, spark plugs...won't jump start ...when clutch started it never fully starts...it'll stay started for a long as it rolling with the throttle fully engaged but is still getting no power and as soon as clutch is pulled back in the bike dies...what could it be?
Submitted: 1 year ago.
Category: Motorcycle
Expert:  Louie replied 1 year ago.

Hi and welcome to JustAnswer,

Thank you for the question and your patience. Should you still need assistance for information purposes only...

Initially, proposed preliminary tries (if have not been done):

  • • check / by pass the side stand switch;
  • • confirm fuel pump is working.


All other checks would be with the use of a multi-meter particularly on the electronic components of the relay assembly and the presence/consistency of the IGN+12V.

Still, attempt to start again with throttle partially open. Other checks (also if have not been done) to consider/try:

  • • carefully remove the sparkplug;
  • • check the burn color of the ceramic at the tip end;
  • • results would indicate:
  • - if black/sooty, then rich and/or vacuum leak issue;
  • - if oily, then an internal engine problem;
  • - if very light brown to whitish, then lean and/or an air leak concern;
  • • check if the tip is wet with fuel; and then
  • • cautiously perform a spark test;
  • • results would indicate:
  • - if not wet or overly wet, then fuel delivery issue;
  • - if no/weak spark then electrical/ignition concern;
  • • consider replacing the sparkplug(s) (even if new and just for purposes of eliminating as suspect(s).
Customer: replied 1 year ago.
Side stand switch is good, spark plugs were cleaned today and put back in, fuel pump has power...could it be my rectifier/regulator?
Expert:  Louie replied 1 year ago.

With a good/fully charged battery, the Yamaha should be able to start and run even with the rectifier/regulator disconnected.

On "...spark plugs were cleaned today and put back in..." please confirm, spark at the tip was visually checked. ...and did the plugs got wet with fuel?

That fuel pump has power would indicate that there is IGN+12V to the ignitor and the red/white wire to the relay assembly.

Consider a hardwire test. Temporarily connect a wire to engine/frame ground from:

  • • the relay assembly's blue/white wire and then the black/yellow wire;
  • • the ignitor's blue/yellow.

Please post back results / observations of the above once tried.

Attempt to start on all instances, observe starter motor action and for presence of spark.