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Louie, Technician
Category: Motorcycle
Satisfied Customers: 11238
Experience:  25+ yrs. experience
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KTM 150 will crank, once given throttle it dies past 1/2

Customer Question

KTM 150 will crank , once given throttle it dies past 1/2 throttle
Submitted: 12 days ago.
Category: Motorcycle
Expert:  Louie replied 12 days ago.

Hi Angela, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.

Initially, a little more background info please:

  • • has it been in storage for a length of time;
  • • is this a sudden recent issue;
  • • or slowly developing while in use;
  • • any recent work, repairs or mods done.
Customer: replied 12 days ago.
This is my son's race bike. Fully stock KTM 150 . We have changes the stator, reeds, cleaned carb , changed gas . He was on starting line Sunday for a race started to take off then at 1/2 throttle bike boggs and won't run
Customer: replied 12 days ago.
Also changes spark plug
Expert:  Louie replied 12 days ago.

What was the burn color of the previous spark plug?

Customer: replied 12 days ago.
Black. Normal plug color
Customer: replied 12 days ago.
Could reeds cause this
Expert:  Louie replied 12 days ago.

Sorry but black is not normal color as it would indicate overly rich, vacuum leak or even an ignition issue.

Expected would be brownish.

Unlikely for the reeds if the idle is good.

Expert:  Louie replied 12 days ago.

Proposed preliminary tries (if have not been done):

  • • re-check/re-clean fuel path (least likely);
  • • re-check the carb particularly the needle as well as the float/inlet valve and float adjustment (likely);
  • • verify correct installation of the air box + air filter + coupling to ensure tight fit with no possibility of an air leak (most likely).
Customer: replied 11 days ago.