hi wanted to pick your brains my mc21 will stop reving out 500rpm before the redline 11.500rpm and it starts dropping off at 10.500 ish what do you think thank you

Is it the same in every gear ?

Hi yes it is it has short cans on it but standard with standard carb setting

And the wire splice ?

Done

I'm sure those with more experience than me would know more, but if it's leaning off at the top end i.e. starving itself of fuel, then it will stop revving out. It might also be the exhausts are a bit coked up. Start with the cheap stuff to check before throwing money at the problem. Will it rev out in neutral or is it under load when it stops ?

Think, Consumables fail/wear/get blocked.

IMO I'd go

Check jets and needles std settings
New plugs, maybe plug caps
Plug Chop - will tell you whats going on
Adjust the jetting accordingly or come back and ask again

HTH

Is this a new problem or has it always been like this?
I have never come across this problem but I guess it could be due to any number of things?
I will just assume that the PGM is working well and the power valves are set properly, although you may want to check these.

Blown base gasket or head gasket
Crank centre seal
Check compression is approx 140 psi on both cylinders

Check airbox and filter flow air freely
Check reeds
Check pipes flow air freely
Check that fuel flows freely into the carbs from the tank and that the tank breather works.
Check that the flywheel spins true and cannot move (up/down/forward/back) due to worn main bearings. This may result in sporadic pick-up sensing?

Umm, that's all I can add for now.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

I don't suppose you just left the choke on?
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Badly adjusted RC Valves can easily knock off 500rpm.
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Ok thanks for the help guys I think it's the power valves when I rev the bike and I see them open I turned it off with the key look at them and the valve is closed in both barrels and when it's ticking over they are open?

Unplug the power valve servo, then rotate valves to fully open, go for a ride and see, if the problem whent away then you know it is the pv's.

get a CBR250 if you want to red line it