I've tryed everything ive even taken it to my local bike repair shop he has swapped out all the parts that are responsible for the spark and its still not working i don't have a clue its still not been rode since i put the engine together any ideas what it could be?

Bad earth for the coil?

I've replaced the coil and cleaned the earth

I'd go back and recheck all the block connectors (sometimes a pin can pop out when connecting together), the orange wire from the CDI to coil, all wires from the magneto, check the contacts, give them a clean up if needs be, you can bet yer sweet bippy it's something stupidly simple, seeing as it all worked before you put the Athena top end on. Oh aye spark plug cap is it nice and clean inside? and maybe try a new spark plug too. Also check sidestand is up and kill switch is off, you'd be surprised how many people are caught out by those two.

I've checked the side stand and kill switch its had a new cap new plug ive also tried different plugs new coil and ht lead cleaned the connectors coated them in wd40 i haven't checked all the pins though good shout ive checked the wires from magneto, it must be somthing rediculously stupid it was working fine untill it blew up

just checked all the block connectors are clean and fine it must be the loom thats the only thing i can think of

Check where the wires come from out of the magneto casing, sometimes they rub and chafe against the casing, and now and again you can get a broken wire inside the wrapping, something that's happened to me in the past, took a bloody age to find it too.

ill replace the wire tomorrow thanks ill let you know if it sparks

There's 30 omz comming off the stator and there was the Same amount comming from a working dt at the shop im going to try replace this wire it comes from the cdi and connects to the coil i got a new wire with the new coil but never changed it as i seen it came from the cdi im going to do that soon

Tryed that wire still nothing actully can't think what it would be

Have you checked the kill switch and side stand wires......my kill switch wire had a brake in the casing when I got the bike and it kept earthing causing the bike to cut out, if your kill switch or side stand cable is constantly earthed the bike won't spark

The little white relay box at the back of the bike,,,left side,,,up under panel,,,,beside water expansion tank.

This is some sort of a neutral relay ( i dont know much bout electrics) but i do know that if this is disconected or broken then you can kick the shite outa your bike,,,,,but it still wont start,,,,wont spark,,,,,wont do anything. There doesnt seem to be any way of checking wheather its working or not,,,,, only try one of another bike or buy a new one.

Not saying this is your prob but worth a look

Did you get it to run? Just out of interest, where did you get the Athena 170 cc kit? I'm guessing it was on line? Was it expensive?

Cheers

everything else has been tested its my cdi, im hoping i find one on ebay as yamaha want £220 for a new one and i got the 170 kit of adrenaline pedstop

http://www.adrenalin-pedstop.co.uk/p/Yamaha_DT125_R_RE_X_SM_Derbi_GPR_125_Athena_170cc_cylinder_kit-1250.aspx