I have a 1999 XV1100 Virago UK spec. It has a loss of power from 3000 rpm upwards. I thought it was carb related and changed the diaphragms and also replaced the needles as the o ring seemed loose and I suspected there was no vacuum being created. this has not solved the lack of power. when I went to test the coils I found out that there was no boost (pressure) sensor present and no vacuum pipe. There were no nipples present on the carb boot also. Did Yamaha alter the UK specs to remove the sensor??? The coils seem to working properly. it seems as there is no advancement of the timing when accelerating. Could someone please give me some advice as how to solve the problem.