How much oil do I need to put in my hyosung hyper 125 when I change it?

You should put 250ml of SAE 10W oil. In my opinion The best brand of oil is silkolene. This site may help you on other types of vehicles : http://fuchs-eu.lubricantadvisor.com/default.aspx?Lang=eng

you need a mitsubishi drive belt from a company called T Northeast in london dont put any other belt on it as it wont last 10 minutes as other belts are not as strong if you look on youtube and type in hyosung hyper you will see my collection of hyosung hypers and ive also got a drive belt for a hyosung hyper if you are intrestid in buying it my contact number is 07794809566 or my email address is [email protected] i work on these scooters day in day out

Sounds like it is running too lean. Look for an air leak around the carburettor manifold.

need a pair of front forks for my 2008 125 xr sm hyosung. were can i buy them from????

i drive my hyosung at around 70-75mph (gt125r) and ive got around 3500 miles on the clock and havent had any real major problems with my bike