electrical?

this problem has been since i bought the bike riding along fine then it loses some power and the tacho shows 0 revs engine will stall if it happens standing still unless i keep revving then power comes back and tacho shows correct revs this doesn't happen once its warmed up after about 10kms any ideas i've tried changing a few things [some little black box i can't remember its name] but didn't make any difference any help much appreciated thanks

Hmm thats that mistical electrickory stuff, only to be touched by people who thinkn they know what they are doing.....

Seriously though, I'd start by double checking all your electrical connections, not just visually but pull the connectors apart and check that all the contacts are in good order ie no corosion on terminals etc. May even be worth while to get a can on electrical contact cleaner and give them a blast, also make sure that all of the connectors are fitting togeather properly once you join the plugs back togeather, some times they can slip out of the plug when they get a bit older.

thanks i have checked them and pulled apart all look fine but i'll try some contact cleaner i guess it might be as mistical as that thanks

Is it a sealed Battery ... like the new No maintenace one's ?.

not sealed just a regular one bought about 8 months ago

pontikat the levels and voltage are fine thanks i'll let you know after i clean all the contacts

I would be checking the coil (s) it sounds like it might have an intermitent faults. You can resistance check the coil. Check the net on how 2.