I baught a non-running 2002 Recon 250. When I first started tinkering with it it had a good spark and it would occasionally start but would only run for about 5 seconds then it would die. I could hit the starter the instant it died and it would immediatly start up again and run for a few seconds. As I tinkered with it the spark began to dwindle down to nothing. Over a period of days as I continued to tinker with it the spark began to come back untill it was strong again. But it still wouldn't run. But as I tinkered the spark dwindled down to nothing again. The CDI was from a 2000 model (which has a different part number than the 2002) but I installed it on a 1985 TRX250 and it worked good. I also connected the coil to the 85' TRX to test it and it was good. I figured it had to be the pulse generator so I replaced that with a brand new unit. When I got it back together it had spark but not as strong as I expected it to be. I still couldn't get it to run for more than a few seconds, and then the spark began to dwindle down to nothing again. I realized that it still does have a small amount of spark; if I crush the spark plug electrode down to where it's all but touching the the center electrode it will produce a spark. After tinkering with it some more I got it to fire up and it actually ran for about 5 minutes. It didn't run great; when I reved it up dark exhaust came out and it missed a bit, but it idled good. As I was trying to adjust the idle mixture screw it died and I wasn't able to get it to run again. It still has relatively no spark and will occasionally fire, but will not run at all.

I baught a used CDI with the appropriate part number for this machine and that didn't change a thing. (I have no doubt the used CDI works)

I'm sure you think that at least part of the problem is carburetion. I'm certain it's not; This has a very simple carbutetor on it and I've had it apart many times thinking myself that it's not getting fuel. The carb is clean and adjusted well enough that it should run. I've also got a spare carb that I tried with no luck. And I've also tried starting fluid which had no effect at all.

I'm stumped. Any insight would be greatly appreciated.  

Hey, I got it running. It was a faulty ignition switch. The material between two terminals was burnt and shorting out the ignition system.

On this machine to test for a faulty ignition switch all I had to do was disconnect the ignition switch electrical connector then use the "pull start" to check for spark.