If raising the idle doesn't sort it then the other major culprits are:

• Old, dirty, choked air filter
• Old, gummed up, incorrectly gapped or poor quality spark plug (be wary that some NGKs are Chinese fakes!)

The other thing is, if you're new to singles (?), then you do have to remember they've only got one big piston and relatively hefty flywheel to keep them spinning at low revs and you have to adapt your riding style accordingly!

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