hi all can anybody tell me what upgrade spark plug 2 use on a sherpa 199B 340? not sure whats in hat the moment. i know my 199A taks a NGK BP5ES. i was just wounlding if there was a upgrade plug to buy. i was looking at the NGK iridumi they look like a good plug but not sure wich one would suit. there is one for a bultaco 350 but thats all it tells you dosent say wich model. or what replacment number its for. or am i just beter staying with a normal NGK? sopose there alot cheaper to buy.