This is a bit of a special bike and is rare in the UK.
Manuals are a problem for this bike. The engine, transmission, brakes and wheels are all from a Honda CB250N Super dream as the engine is a 249cc not the smaller cc in the 250C. Yours should have twiin Makuni CV carburettors and the 250C has a single carburettor. The front brake is a left hand disc with a Nippon made calliper which are very hard to find so never throw it away.
The clutch cable is different and the whole engine and transmission is different. If you look at your bike you will see it has the longer silencers which are the same as the super dream 250N.
You will be better finding the Honda CB250N super dream manual from 1979 to 1981. I know these bikes inside out. Yours will have a Rev Counter and a display for warning lights between the Rev counter and the Speedometer.
Never throw the master cylinder away as you will never find a genuine replacement but the repair kits are available.
The Honda CM250TB is a very reliable bike and is quicker and accelerates faster than the CM250C because it has the twin carb arrangement,
Never throw the carburettors away as they are also very rare with a 17 cm between the 34mm inlets to the engine ports. you can buy all the overhaul kits and you will find there are no accelerator pumps on them which is a good thing. The rear mudguard is a corrosion issue but the Honda Rebel has the same mudguard and the Rebel front mudguard can be made to fit and are a quarter of the price of the copies made by various company`s
Parts are hard to find but the super dream parts fit in most cases even the alloy wheels.
You need to keep this one running as it is a very desirable rare model in the UK. There are still a few in the USA though but most have been bobbed.

Enjoy the bike as yours looks pretty good and has a few years in it.

Best Regards

Noel