hi guys first thanks for all your suggestions and your patience on this one --still not running right, plug always looks dry ,engine hot,put a 46 idle jet in carb thought i had it ,ticked over ok but when reved slow to come down --- farted about with air screw-- turned into a bag of bolts sound but sounded quiet before this---is it maybe a fuel problem have taken a top end compression test and constant at 90psi is this good?? have immersed stripped carb in solution will leave and blow out later this week after this i am at a loss kind regards a rather depressed sherpa owner murray

hi what carb have you got on it?

hi bondy its a bing carb---a possible solution has appeared via my wife who spoke to bultaco uk ,they say this has become very common for bultacos due to the additives in the fuel and have gave her some tips to try which i will do at the weekend and let you know thanks for your help bud cheers murray

ok try what ever they said. its just trail and error really. i got a new makuni carb works great on my bult. but not cheap but well worth it. carbs have to be spot on to get the bike running proper. it can be verry frustrating have you check you have te corect jets in? the slide could be worn or the needel all could cause problems. hope this helps.

hi guys just to close out this topic.....re-bore..new piston kit...small end...changed mix to 50:1 ...quality petrol...octane additive..fully synthetic oil.....new pressure test at 115 from 90psi..completed first trial yesterday the bultaco was so crisp and ran so well will have to adapt my riding style to compensate thanks for all your helpful comments guys and lets keep these old girls running cheers Murray