Carb gods, please help!

[meowmix]

I am having a huge amoung of trouble getting this sucker sorted.
(Note, I was alot gentler and thorough then the following indicates)
Backstory: Its a Kwakka KLF300C Quad, treated as any farm quad is , anyways, I took on the task of fixing it.
It was rich as hell and leaking fuel constantly. Took off the carb, full clean, ultrasonic clean, looks new. That didn't fix it. Next is where the fun started. The Float jet is a pressed in item, no chance of getting a replacement one. Lathed up a steel punch of the same taper as the float needle, banged that in a few times, then had to tap in a little bit of thread to pull the jet out a bit to its previous level. Whoops.
Then used that tool to lap the jet, good clean reset everything, test. Good.
No leaks, awesome.
After cleaning the entire intake, it started right up. Had it running for several minutes, then it died. Like someone hit the kill switch. Trying to start it from here resulted in considerable backfires, and the occasional sneeze through the carb.
WTF.
Our theory from here is that the needle is hanging up on the threads in the jet. Whoops x2.
Any other theories?

[tri boy]

Backfiring etc is often attributed to an ign fault.
Can be as simple as a poor wire connections, through to faulty components like stator coil/pick up/ CDI etc.
Good luck

[meowmix]

Yea we were stumped for a while. It suddenly switched from running nicely to off and backfiring. I couldn't fathom a reason for it. Nothing apart from the carb has been touched (well, and the plug). Grr. I'll do some more tests tomorrow. Speaking of which, does anyone know of or have access to the Service Manual? I can't find one online.

[tri boy]

If the carb has the mixture so rich that it is fouling the plug, then that could help explain the backfire.
If it's soot black, then the carb/fuel delivery sys needs further attention.
Can't help ya with the manual, but it is still only a 4stroke single with maybe only the solid state ign sys to add complications.

[jaytee2]

Did you put fresh fuel in at the time as it could have water in it ? Water in the fuel will cause the engine to stop and / or back fire. Don't ask me how it gets there but it's not unusual.