HELP...engine problem not sure what it is?

[94bluZR2]

i have an 01 400ex and when it warms up, when i am going through the gears at the end of each gear the whole bike jerks, as if it was hitting a rev. limiter but i have a CDI rev box and i thought that might be the problem so i put my buddy's big gun over rev and it did the same thing.

im not real sure what that means i thought it could be a valve problem because it only does it when it warms up but im not sure so i thought you might be able to help me out.
Thanks

[leasureryan]

valve sticking? moving parts not moving as they should I would say...I'd have to see/feel it for myself to really say, it could be the electricals cutting out to...who nows

[94bluZR2]

okay yeah i thought it might be something like that but i wasnt sure
thanks for the help.