kdx 125 not starting

[dougle09]

ive just had my engine fully rebuilt and had a problem with not getting a spark but im now getting a spark due to ht lead being faulty but its just backfiering and not kicking over it has plenty of fuel and theres fuel getting to the carb but im now stuck and any info would be appreaciated thanx

 

[KDX175MMI]

I have a 1980 KDX 175 that has the same symptoms, It was running no problem and now it wont start. What year is your KDX 125? The older 125's used some of the same parts as the 175, but you probably have the newer verison. I am going to post a full thread tomorrow about my KDX and what I have done so far to try and get this thing running again... and yes I have checked the obvious stuff like gas/carb, piston/cylinder, and pressure tested the engine..

 

[EYY]

Did it run prior to the rebuild?
First place to start would be a new plug and cleaning the carb- paying special attention to the pilot jet.
If that doesn't fix it I would inspect the reeds for cracks/chips and check for air leaks. Did you replace the crank seals and reeds?

What does the spark look like? It may still be weak...