Strange idle problems!

Hi guys just recently rebuilt a 2011 te 250 xlite bought it seized so not sure on history has the txc ecu and injector,rebuild went well done away with electric start but kicks fine, problem is the idle starts and burbles away fine but put in gear and revs rise to around 5-6k pull away and will drop right back down again checked for leaks throttle cables are fine etc cant work it out standing idle is around 2300-2700 which seems a little high too any help appreciated cheers jon

If you don't have I-beat think about getting it.

Where are you?

My 250 idle is around 2300

Hi im in the uk will take a look around but sounds expensive! Going back to 300 2stroke!!!