Guys sorry to drag up ANOTHER txt50 starting problem post, but I have read all the other threads and haven't found a solution yet...
What I have tried:

Fresh fuel.
Check fuel is flowing.
Air filter cleaned and re-oiled.
Carb stripped and jets blown through.
Removed spark plug, check for spark: spark present.
Pulled apart stator and cleaned.
Checked earths.
Kicked and kicked until my leg fell off.
Not a sign of the bike wanting to fire up...

Any ideas, pointers on how to breath life back into the gas gas boy?
Cheers - Boner.

Hi Boner, A friend & I both have the same problem. The only common thing we have found is that both our rotors have hairline cracks running through them. The other troubled soul has had delivery of a new rotor (& stator CDI) but hasn't had time to fit them yet. The ignition really is a weakness, but on all the problem bikes they do seem to produce a good spark.
I know a while back someone posted details of using an alternative system. I'm sure there must be an alternative to the selettra unit.

I had the same problems on a brand new TXT50. Eventually traced it to a distorted reed block which meant that even with a super clean carb and a healthy spark because the reeds were not completely sealing there was not enough vacuum at kick over to draw fuel. I replaced the block and made sure that the seal was perfect and the bike then started first time every time for the next 2 years!
Quality control is not great with these (Chinese manufactured) bikes....

Mmmm - haven't checked the reed block.
Will whip it out over theweekend and take a look.
Thanks for the pointer.
Cheers - Boner.