29-06-12, 08:45 AM
Sounds like something i had a while ago. I called it tractor mode. Basically it would drop a cylinder at low revs not pull and sound like a massey fergusson at idle. It turned out to be no 2 plug cap the insulative qualities of the outer coating had failed. What gave it away was i made the bike wet pushed it in the garage started the bike up. lo and behold tractor mode. I touched the cap got zapped after recovering i turned off the lights. only to see a pretty light show coming out of the side of the cap. got a new cap (NGK) not original never done it since. For reference genuine cap are around £ 40 per cap NGK are between £6 And £10 depending on where you shop. Hope this helps.