well i may have nailed it
it turns out its a common issue with gpx250r's
when i had it serviced last the mechanic filled it right up to the top level with oil when it was cold
after reading on ninja 250 forum many riders have experiance the same issue when riding 9000 plus revs. they have suggested to reduce oil level when cold to centre of upper/lower limits of oil window. and that fixed prob.
now last week and this week i just thrashed the fark out of the bike and was doing 10,000 -11,000 on back roads
as with last week out all day i thrashed the little bike again
then and recently on weekedn are the only times it has done this.
will try reducing oil to just above half at cold
another issue mentioned is an incorrectly fitted breather tube which i will look at if this doesnt work
thanks for the advice regardless guys
knew i could count on help in here
