I need to know how to set the sag on my 2003 Rm 250???

Hey Tom, sound to me like the carburetor needs a professional cleaning and setting.... do this and see what happens..

The engine doesn't use oil,the only oil it gets is from the 2 cycle oil mix in the gas,the transmission uses 85\90 transmission oil such as bel-ray or others. I would NOT reccomend running 10\40 in the trans...

sounds to me like shes nipped up in the bore possibly to a broken ring or lack of oil or coolant unfortunately the damage is done you will have to remove the cylinder head & barrell to determine how much check the oil pump for blockage & function was there adequate oil in the tank alsowas the coolant resevior full at the least it will need a set of rings & the cylinder honed at worst big end bearings if the bottom ends locked up this involves splitting the cases so for your sake I hope my initial diagnoses is corrrect

Chances are the float level is set too low.

39nm buddy

The 8mm head bolts are torqued at 19 - 21 ft/lbs.
any smaller 6mm bolts are torqued to only 6 ft/lbs
like those on the lower cylinder.

my bike runs best 40:1 but you can run it 32;1

Hi .... Try this site for the oil.

http://www.opieoils.co.uk/c-852-recommend-an-oil-for-my-motorcycle.aspx

Other problem sounds like carb or air filter. Does it spit back through carb ?