I just picked up an 01' xr80 for my son that does the SAME THING. I guess we can add it to the list of countless posts about the web for this exact issue on everyone elses XR80's. Seriously, it's everywhere. What's the remedy for this? Clearly the fix is the same for everyone's, the problem is the same so the treatment must be as well. I popped a fresh plug in mine and rode it about the yard giving it WOT whacks over and over making the bike die out. Checked the plug after 5 minutes or so and it's building a soft chalky black deposit on it. The bike seems fine other than this condition. Trying to get definitive answers on carb stuff over the interwebs is seriously proving useless and time wasting it seems. Someone has solved this problem and knows the answer I'm sure of it. I mean I can putz around with this carb all day but I don't really know much about what I'm doing. Jet up, jet down, shim this, raise that. I just can't put it all together as to what each change here and there are doing in the end. I feel your pain Deano66, hopefully someone can put a pin in this for the 80 owners.