Hey Team,

I've noticed at the last couple of rounds of racing that at the end of the race my bike doesn't want to come to an idle.

If I leave the clutch out and brake the bike to bring the revs down it is fine otherwise it wants to sit at about 6000 RPM.

I thought my bike must have just been keen to keep racing but thought I should check what the underlying problem might be.

Any help would be great!!

That's a strange one bro - my motor's revs sometimes hang a little high (3000rpm) for a second or two before the powervalves move, then the revs drop to tickover normally. So maybe check the powervalves are moving through their range ok and responding to throttle movement as they should.

Errr, whenever anyone says anything about the revs creeping up or staying high i instantly think air leak so i guess that's a possibility - maybe when you put fresh pistons in it you should do a leak down test if you haven't already?

Are the carbs definately snapping fully shut on their own?

Is it running 100% normal when you first start it up?
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After years of moaning about immigrants now i am one...

Hi ,

I would also think that it is related to air and fuel . Check your tank breather too , if it is blocked it may contribute to your problems . Check your pilot jets too .

my bike would hang up at higher RPM until Matt of Tyga fame cued me that my idle setting could be too high (supposed to be about 1250 or so) - that cured it. Hope you are as lucky.
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-Jim
'93 MC21

My MC21 was hanging at 3000 - 4000 rpm coming down to tickover when the engine was sucking through a failed crankshaft seal.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

RichG wrote:
My MC21 was hanging at 3000 - 4000 rpm coming down to tickover when the engine was sucking through a failed crankshaft seal.

Same here.

Although, as Jim has pointed out, if the idle is set a little too high the revs will often hang as the powervales will be in limbo and it upsets the slow running balance.
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Andy.
NSR-WORLD.COM

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yeah the idle speed thing is what causes mine to hang high for a second or two before the power valves move as i let mine idle at 1500revs to stop the exhausts from shaking so violently.

You should deffo leak test it and it might also be worth checking your fuel tank breather as Neal says, maybe it got blocked when you re-sprayed it in baddass black?
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After years of moaning about immigrants now i am one...

Good as gold guys!

I'll investigate those options and hopefully find what it is!

PLEASE NOT CRANK SEALS............