Been seeing a lot of carb. questions as of late and wanted to address the prob.
A old school fix for any carb. car truck atv what ever is the "hand choke"
after sitting for days, weeks or months or even years the fuel dries out in the carb and the tank....leaving junk or trash in the system.

Try this: Fresh gas after that try the following:

If the bike will run at all, remove the air filter and with the bike running as best it can,
giving max rpms as best it can use your hand to cut off the air flow to the carb. for just a second, repeat this for a few times and try not to completly choke the bike off.
I have seen this work so many times it is not funny. This will help suck the trash out of the system and the bike will run better.
A good dose of sea foam or mmo will also help.
For bikes that wont run at all try "starter fluid" to get it running and then do the "hand choke"

Free and cheap is always better than a full carb. rebuild.
Al