Hi There,I had the very same problem with my r5k,I bought it and the previous owner told me it dit it, 6000 rpm on startup not ideal for a cold 2 stroke,he had tried allsorts but never cured the problem,after start and a couple of mins it dropped down to 3000 then 1100 ater that the bike ran fine,He gave me a pair of carbs with the bike and said he never got round to fitting them,the other day the bike started loosing power at 10k,i posted a message on here and got some possitive replies, one of the main jets shook loose and fell into the float chamber, i thought this was the problem we refitted that then tried and checked hoses,inlet rubbers,fuel tap,reset float levels,still the same,enough was enough I fitted the spare carbs std jetting,and it started on choke 1800 rpm and as soon as you turn it off it idles perfectly under 1000,and is much sharper low down,The only thing i can find wrong with the old carbs is the slides are very loose and rattely compared with new ones,the carbs look fine but there was definatley somthing wrong, TPS ????? perhaps i dont know, but its sweet as now,goodluck,jonmac
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John