I have owned a CRM 250 MK1 (MD24) for a year and half now a few weeks ago it just lost all power (piston ring) so I replaced piston, gaskets ect.. I've had 2 strokes for a couple of years and allways rebuilt them myself, I took the barrel off and changed piston, put it back together now it won't run at all! Has high compression, Its getting fuel and everything, I've checked for spark and there isn't one, no wires been messed about with... All connectors changed for new ones, bought new cdi unit, coil ect ect still nothing, has anyone got any advice on what it could be?? Thanks

Oh and when I kick it over I get the orange side stand light and neutral light front light ect all come on when kicking it.

Welcome, that sounds odd. Do you get any dash board lights when you kick it over?
It might pay to take the plug out, and spin the back wheel to see if there's any any power being generated, to check the lights etc.
Otherwise a connector block somewhere sounds like the culprit.
Mike

Ah, try pushing the bike around in gear, but with the plug out.
Check the cap and HT lead.
Mike

Kill switches are also a good source of troubles.
Mike

All lights on dash come on when kicked, pushed in gear ect, it ran before I changed piston was just very low compression, I'll try the kill switch

Thanks for the help

Sidestand switch is a highly likely culprit of this is stil connected?!

There is a very very weak shock when spark plug in condenser touching metal! Any ideas thanks?

You say weak?, you won't get one of those big fat blue sparks like a battery system would provide.
Again, with the plug out, put the bike in 3 or 4th gear, with the fuel OFF , push the bike around for a short while to vent the crankcase.
Put a NEW br8es plug in.
Fuel on , choke on, a tiny bit of throttle,
ignition on, full kick, any result
Mike

as mentioned sounds like side stand switch (moe hassle than what there worth)

Update*
Now has strong spark (nice shock) but still won't run! Getting fuel and has high compression. Any ideas on anything else to try???

What do I do with the side stand wires? Can I just disconnect and not use them?? Sorry I'm no good with the wiring lol

Side stand - viewtopic.php?f=20&t=8779