bogging out in 2nd gear

[arctic15]

i was out riding today. took my bike thru a lil mud not much at all, it was in second gear after about 20 feet it just started bogging out like it wasnt getting enough fuel. i dropped it down to first gear an it came right back to life. i dont kno why it would bog out in 2nd ive never had this problem before and ive gone thru alot deeper stuff when its been in 2nd gear . any ideas to why it might be doin this?
 Thanks

[mrbones]

Does it shift through the other gears (3-5) ok?

[Chevy1500z71]

need alot more details then that. is it sputtering, choking, does it black smoke, sound like its gonna die or just keeps going but has no power.

the issue has something to do with the carb, pretty much always comes down to the carb. has it been sitting a long time, it only takes about a month in some instances with ethanol fuel.