Brand new plug, tried 3 different ignition coils (original, new, and one from an 86 trx250a which is the one I'm using now), tried 2 different CDI units (original, and 86 trx250a's. Original is back on machine, all plugs have been sprayed with contact cleaner and put back together with dielectric grease, carbs been cleaned twice, valves have been checked twice. I'll be able to start it once then shut it off and start it again, but I'll try and start it up half hour to an hour later and it won't go, then try the next day and it'll fire right up in a first few kicks. Any insight on what could be it's problem would be great. Thanks in advance.