[Andrei XVision]

hello, I have a problem with the yamaha yzf r125, when I remove the db killer and drive it until it warms up, the speed drops and it dies even when cold, when I start it, it runs perfectly and when I rev it once, the yellow light flashed from what may be?

 

[NorthCust]

first: what year/gen bike is it?

are you talking about the yellow "error code" light? if it starts flashing does it do a sequence..e.g. several long flashes followed by several short flashes? That's usually how you get your error code (on gen1 anyway, can't comment on later ones).

Does it run ok f you leave the DB killer in?