My kxf250 will no start it was such a good bike started first time evry time then rideing it hard one day it was fine left it for a week and it did not start and had no compresson so took it apart rings clogged up cheep oil i know but pistin good barel good rings good velves goog fuel getting in ok timing set spark good but still it dosn't start i don't no what to do . thanks

Hi check your gap on your velves it should be about inlet 0.13 and ex 0.18

Hi mate sounds like you tested all the standard stuff you obviously know what your doing - In my experience when I get a bike like this where all seemingly is good and set correctly but no sign of life when trying to start 99% of the time ends up being the stator.
And I know it seems strange but I honestly up to about my tenth bike now where even though shows spark at plug when kicked over test, the stator still at fault when tested with Multi meter (way out of spec.)
If you have your repair manual flick through and get the spec ranges for the resistance on your stator then disconnect the stator lead at the CDI end and its very simple set your meter to ohms and plug into each pair of wires (usually 3 pairs) and see what readings you get
don't worry to much if you don't have the spec range as if it is the stator you will quickly notice you get zero reading on one pair of wires if not all three?
let me know if you want more clarification on testing
If all this fails to assist then my advice would a be leak down test to diagnose compression leaks, open valves, gasket leaks etc Then I would pay attention to the pilot circuit of the carbi, Double check your timing and valve clearances, Then I would be back to testing stator again?
Very rarely your coil pack (spark plug cap) can fail but be worth testing it when you have your multi meter out ( you looking for about 0.08 - 0.10 resistance reading on it) and even more rarely the CDI box can fail, no real way to test this apart from plug new one in and test if cures things...
Being that 5-6 years old and you know the bulk of how to fix and maintain this sound more and more like a stator problem..
On the up side if you do need to change the stator great opportunity to change cam chain aswell they run like brand new with full stator power and a brand new cam chain
cheers mate .... Good luck!