good day .. ... i am currently racing a vfr400 nc30 ...the bike is running a total loss wiring loom but the up graded the piston not too long ago it did run for a few secound then just shut down & ever since i cant get it to even fire up at the moment jusy want see if anyone has had similar problem before or where i could start looking to solve the problem

Need a bit more Info.
Do you have spark at all?
Did the bike just stop completely or did it loose a couple cylinders and then stop?
Guess it is winding over OK?

regards
jon

what piston did you upgrade to?

Chris, are you thinking the piston crown has hit the plug too?
Take the plugs out and check the tips as the gap may have been reduced to nothing and consequently not sparking.