My sons crf150 has run great and starts first kick every time. The bike is only a couple of months old. Yesterday it started first kick and then stalled after a couple of seconds, now it will hardly start and when it does it runs like crap and then stalls again. It will only run with part throttle open and if you try to rev it it dies or close the throttle it dies. It seems like it is running with the choke out, tried changing plug but still the same. Blown idle and main jets out as well - Any ideas ??? what could be the problem. Thanks Guys.