Motorcycle Repair: wet plug foul, yamaha rd 250, check air filter

Question
Hello  I have a 1973 Yamaha RD 250 street twin stroke
the left side keeps wet fouling plugs,plus gas-oil mix
comes out of the end of the muffer,could this be cause
of a bad piston ring or head gasket or carb ??????? THANKS
                              rolloootide@yahoo.com

Answer
Awesome bike. I would pull carbs and make sure all is clean and float levels are spot on. Also check coil and wire on that side - make sure it's all in spec. Check air filter is clean and not excessively oiled. Calibrate carbs.

See: http://www.motocom.com/motorcycles/1973/1/1/2793

If you don't have the factory manual I'd invest in one. Third item down on the list.