FZX 250 Zeal cutting out at speed

[doctorprox]

I have this wierd problem i just cant seem to fix.

The bike is fine at low speeds, and i can redline the lower gears easily, but when i get to like 100 kph in 5th it starts to jerk like its running out of fuel. If i change up into 6th it just dies out and slows down.
Its not a specific speed that it cuts out at, i tried changing into 6th at about 40kph and when i got to 70 it started doing it and slowed me back down to about 50 where it picked up a little bit but wouldnt accelerate.

When its doing its jerkyness, if i pull in the clutch and rev it, it kind of gurgles for a second and then revs up.

At lower speeds it fine in these gears, and the fact that i can redline 4th confuses me.
Ive had the carbs in bits and they are clean and seem fine.

Any ideas?

[Sniper]

Check your plugs and leads?

[John]

Could also be a fueling problem... make sure you have the right size main jets in it.

[Rod Steel]

could be a fuel/oxygen sensor problem. Ive seen similarish effects in cars when the sensors start to go,, but then im not very mechanicly minded so i prolly dont know what im on about... :weird:

Cheers
Aaron

[Hitcher]

Zeals have got a flat spot at about 6,500-7,000rpm, which is about 100kmh in top gear. It's really irritating until you get used to it. Don't be afraid to wring its neck -- the Zeal should happily rev to over 12,000rpm (Probably why I got such piss poor economy out of mine. That and my aerodynamic, sylph-like body.).

[doctorprox]

Its definately no flat spot because once it starts doing it, it slows down and i cant matain my speed.
As for plugs and leads, the plugs are new and ive just checked all the leads. Could new plugs cause this?
I was thinking if it was the plugs it shouldnt be able to redline 4th gear right?

[Hitcher]

I'll go right out on a limb here and predict that it's either a fuel or an electrical problem...

Ahem. How about you take it to your friendly Yamaha dealer and let a qualified mechanic give you an opinion.