Im having problems with the revs dropping off slowly, when stopping or just by pulling the clutch in the revs drop slowly to 3k then stay there for a few seconds before dropping to tick over, this happens all the time and is not just intermitent. Im guessing an airleak somewhere but i thought a air leak would make the revs more eractic???
Bike is stock apart from the wire splice, airbox is also stock for the time being. When starting from cold the engine revs will rise to 5-6k without using the choke and then after 30 secs drop very slowly to tick over, i cant seem to find any info on weather this is correct or not but im guessing not.
Im prepared to remove and strip the carbs but just looking for pointers as to what may be causing the problem. Other than this the bike runs great, a little rough down low sometimes but sweet as a nut once it gets going and pulls strong upto the redline.

my r5k is exactly the same. buggered if i know what causes it as i've had everything apart.
think my clutch is dragging a bit so might need gear oil change.

Mine did it with duff crank seals.

It can also be a slightly high idle/throttle linkage stop setting. Try backing the idle adjuster off a little (get the idle down to about 1100rpm) to see if it helps.
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Andy.
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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

Cheers for that fella's. i have set the idle high, about 1500rpm+ so that could be the problem, i just feel 1100 is too low but if thats what its gota be then i'll see how it goes tomorrow. If not then its carbs off

Well andy you were bang on the money dropped the idle to 1100rpm and all is good, ive got use to the low tickover and the revs drop much quicker now although still not perfect but that could be me. I'll check the crank seals at a later date but for now its good enough. Revs only rise to 3k rpm from cold now so that'll please the neighbours.

It can also be a slightly high idle/throttle linkage stop setting. Try backing the idle adjuster off a little (get the idle down to about 1100rpm) to see if it helps.

where is this idle adjuster? can someone direct me to a idle adjust how-to or a page # on the web manual?

*edit* nevermind...found it:
http://www.nsr250.net/forums/members/web_manual_mc18_21/titanium/index.php