Electrical help?!?!

I've seen the sparkplug boot wear internally and not make a good connection with the plug, the wire itself corrode/break, or the wire comes loose from the coil. Also, look for a corroded ground on the coil, or better yet clean it and the frame with a wire brush to make sure your getting a good ground.

Don't rule out the fact that it could be a bad plug as well. Hope this helps.

isolating a erratic electrical problem is very aggravating to me also. Guarantee that when you go too look at it the actual part that is the problem you inardvertently fix it by jarring it just right some how.

I would do the easy free or cheap things first. As stated earlier new plug making sure the contacts in the cap are good and tight on the plug ,all grounds and connections , good clean and tight including motor mounts also and maybe a funky kill switch. After that break out the ohm meter and check the stator and ignition coil for proper resistance according to your manual and hope you can actually see something is a failure. After that it is basicly a crapshoot changing parts at home or sending it off to a dealer.

any of the trouble shooting trees in the manuals that I have seen state

check plug, cap and connection
check kill switch
check all wiring and connections
ohm resistance tests
if nothing found replace cdi

Yep do as stated above.. But also look at the wiring where it runs thur the saddle/ loop that holds the harness below the handle bars look for any wear on the outer jacked.. Also check the kill switch. It could be bad or broken.

With some aftermarket black boxes on TRXs they dont like to start when cold out so riders take them and warm them up on the truchk defroster . WB extended rev limiter boxes espescially . They work good otherwise just dont like to start when cold out . Maybe yours has the same trouble even if a stock box . Try it . NC might not be very cold . Electrical parts are tested with an Ohmeter for resistance against a manuals specs. Ive seen some Hondas with that little rubber mounted coil , the coil will wiggle around a bit and the 2 female electrical connectors will or may lose the crimp or become frayed right near the crimp . Mostly XRs & quads . TRX 250Xs also get their ign wiring messed up when the chain gets wadded up in the L/S case if the chain pops off . one time I had an Xr where the little pulse generator/ign trigger got all metal particles from engine wear all stuck to the trigger and fouled thing out . in a four stroker with a generator the magnets on the flywheel always seem to attract all the unattatched particles floating around in the motor . And you gotta watch what you clean some of those flywheel rotors with cause 2&2 and carb cleaners can melt the epoxy holding the things together . Sometimes you can check all the stuff with a Meter and still wont work or make spark but then you plug in a new CDI or stator and it lights up . One time I had a real problem with a KAW Bayou 220 that had inter or no spark , we tried everything even parts from another runner and were amazed to find out the Ign rotor magnets lost their power . The thing needed a new flywheel . We lost four or five hours on that thing . sometimes elec problems dont make sense until all is done and things are fixed . Good Luck On your TRX .