err servicing ar....very hard to explain leh...i also dunno
leh...u guys knoe??
as for the km...i think every 10km if u r rich and 50km if u r
average and 500km if u r poor kekeke 
servicing = wash ur carb/change black oil/spark plug/ wash air
filter/ err got wat else ar???
how long do once = when u happi u go not happi den dun go lorz...a
about every 2 mths den go servicing one....
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| b|t3!!