actually not really must go 4000km... as long as u feel ur bike
engine getting chorchor, n changing of gears like not so smooth can
change engine oil liao 
when u go to mech, jus ask them wat other stuff can they do for a
full service besides changing of engine oil n spark plug, they wil
tell u everything..
carb, valve, filters r the basic common things, i heard my fren say
stil got many other small small parts...too chim liao..
but i tink basically the mechs wil do everything for u lor,
provided u tell them properly, maybe can ask them to check ur
coolant level, battery water level, brakes....etc...
many many other small things...
i stil NEWBIE leh... 
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