I'm a long-time dirtbike fancier/new dirtbike owner of a 2005 WR450 which I purchased 2 months ago and have had the pleasure of giving a decent run a few times since getting it. The bike seems reasonably solid (to a person who is very green with this sort of thing, but eager to learn) but there is an issue that is detracting from the fun and causing me, and some of my mates with bikes, some headaches as we can't work out why it's doing what it's doing. The bike starts ok when cold with the choke on but will not run at all without the choke on unless I have some throttle. If I have no throttle it will idle for 5-10 seconds then die. When the bike is hot, I still need to have the choke on or as soon as I idle the same problem happens. I also have to have choke on to start it when it's hot. My neighbour/mate who knows a lot more than me thought it may be a problem with jetting and pulled the carby off and cleaned it out, but everything looked fine and when put back together, the same thing was happening. The bike hadn't been used very much over the past 2 years but had been serviced in the past 6 months before I got it (and not ridden since that service till I got it).
Apologies if its a stupid issue