Fxr150 wont rev out ?

[yamaha250f]

Riding to work today my bike wouldnt rev out
You can give it full throttle in any gear and it revs good in that gear but when you change gear its like its used all the gas up and wont rev very hard in the next gear ie sit at the lights then take off and it will slowly rev to 7000 rpm then go hard from 7 - 12000 rpm as usual ,change gear to second and it has absolutely nothing taking around a second to gain 1 km more per hour !!
If you cruse for 40 secconds then gun it again it goes fine again .

I havnt riden it for about 2 weeks previosly and it was -4 when riding to work but still doing the same when i rode home in 7 degrees temp .

Gas was on and gauge showing half a tank choke was off and tryed it partialy on no difference bike is a 99 fxr150 with only 8000 km on the clock ,its got fresh oil and new plug 300 km ago .

Any ideas or things to try ?

[R6_kid:Me]

www.fxr150.co.nz

Sounds pretty wierd - maybe you've got water in the fuel? A couple of cap fulls of methylated spirits should clear that up. Give it a fresh tank of 95+ gas and see if it helps.

[Buddha#81:Me]

Diaphram for the CV carb may be ruptured. Blocked air filter.

[wildpudding]

I would get someone who knows their stuff to look at/adjust the carb.

Mine had similiar K's and developed a flat spot in the mid rev range, turned out the main jet inside the carb for some reason was set too low (ie. too lean[not letting enough fuel in])

Stefan