I have an 05 WR450 with an FMF pipe, uni filter, grey wire mod, smog delete and some holes in the air box. The plastic hot start nut broke and everything seems to have gone downhill from there. We replaced the hot start return spring and plunger and put on an aluminum nut now which is much stronger. Yesterday we cleaned the carb and checked the float height and everything seemed ok inside the carb. Main jet was 165 and we put in a 168 Pilot is 150 I really have to pump the gas alot before firing the bike and it will not idle at all. We started to think there was a vacuum leak and sprayed some carb cleaner around the carb and the rpm's spiked right around the carb-engine rubber boot. I am going to replace the boot, but mine looked fine with no visible cracks. Do you think that the small vacuum leak there is going to cause all these problems or should I pull the carb apart again to check for more sand or dirt in there. We were pretty thorough with the cleaning so I'm fairly certain theres no more dirt there. I just ordered the boot but trying to figure out some other things to check as well.