My husband´s 06 c50 died while riding. Trailered it home, tried to start it, made a few grinding noises somewhat to a flywheel with a broken tooth but no start. Put in a new battery, new plugs and a starter solenoid. It will now start but the idle is very low, won´t stay running unless it´s throttled. There seems to be a small bit of oil in the air filter housing and what looks to be an oily pcv valve? from the intake. Bike has about 40000 miles. What do we need to do?