When it's cool out it doesn't run too bad but if it's hot after about 15 min.'s I have to choke it to stay running,then after awhile I turn the choke off and it's fine for awhile.I had a new coil put on ,taken the carb off and cleaned it,changed the fuel filter with no change.it used to smoke (white)for just a minute,now it always smokes,so I'm thinking valves.now this is weird and maybe just a coincidence,but sometimes it will barely turn over and this makes the battery terminals super hot.I unhooked the wires to the starter and cleaned them up and it started right up and ran just fine.then like the tird time after that it wouldn't start,retightened everything and it ran fine.could my starter or wiring be bad causing it to cut out when it gets hot or the valves not seating properly.I've rebuilt lots of 2 stroke topends(I know that's easy)but is a valve job difficult to do?and could this be my problem.thanks for any help

It could be the problem, but you need to remove the air filter and see if there is oil in the air filter housing. If there is oil in the air filter housing, you have a bad breather assembly, which is allowing oil to enter the carb, which is causing the white smoking. And setting the valves is a piece of cake.

No oil in the filter.I think it's a bunch of things.I guess I should've mentioned that all my problems started when I flipped it mowing a jump on my motocross track.I'm thinking of just getting rid of it but I don't want to spend a lot of money on a new one when a couple hundred bucks might fix it.