I have a 2008 CRF70F that has sat for about a year in a garage. Took it out, cleaned/adjusted the carb and it ran great for a day. Then unable to start. Purchased a new carb and installed/adjusted, (old one had some issues) and the bike ran like new. I rode it for about 20 minutes in all three gears with no issues. Put it up for the night in my garage, went to ride it this morning... nada... will not start. Couple of coughs with white smoke out tailpipe and and some reverse flow through the carberator. Not sure if it is timing, burnt rings or valves, compression issues... it seems like no compression... but how does that happen overnight.
Frustrating...