Attached is a short and to the point maintenance guide covering the basic info for your CBR250.
While it isn't as detailed as the service manual it does cover the basics that are useful to know and specifications for parts.
Chain: CBR250R(J+K) + CBR250RR(L+N+R) : 428 Pitch, 136 Links
Chain Slack : 20 – 25mm
CBR250R(J+K) : 13 Litres + 2 Litre Reservoir
CBR250RR(L+N+R) : 13 Litres + 1.6 Litre Reservoir
It also covers what needs servicing when and even torque settings for which bolt!
Here is the complete service manual. it covers EVERYTHING.
(low quality, black and white images, but small size, ~11mb)
(High quality but large size, ~170mb)
that link is now dead BUT jlyall has uploaded it using his own account, so just follow this link to his post http://cbr250.com/forum/thread-425-post-53663.html#pid53663
If it isn't answered here then start posting questions on the forums.