Bike stalls at idle?

OK so the last thing to repair on my Wr450 would be its nasty habit to STALL when it idles. So here's how it goes

ride for a bit engine works great, tonnes of power in every gear very smooth through the rpm range, close the throttle and come to a stop and let the bike idle, very quickly it will stall [about a minute]. When I go to kick it over it usually backfires once then starts up perfectly, will idle for a while and stall, I have to rev it a bit to keep it going. its not that it is idling too low, I have it up at a pretty good rate. Any idea why this is happening? fuel air mix wrong? maybe due to the uncorking i need to re-jet the bike? Just stop being lazy and clean the damn carb?

Dirty pilot jet perhaps?

Could very well be, however it could also be some of the following. Since the maintenance history of your bike is unknown I would look at doing the following.

- check valve clearances, adjust if necessary
- inspect/clean/sync carbs
- change spark plugs
- inspect fuel hoses/filter, seals, gaskets (including that recently changed head gasket) for leaks
- inspect petcock and gas tank
- check ignition timing

Manual for the 2006 WR450F
http://www.yamahaownershandbook.com....J-28199-43.pdf

Valve Clearance Check - Video created by GTAmotorcycle member xhumeka . WR450 valve clearance done)
http://www.youtube.com/watch?v=yNJ9Da2dF-Y