Why is oil coming out of my crank case vent hose

SOURCE: getting water in the crank case

if i had to guess at this one the seal behind the impeller on the water pump is bad

SOURCE: crack in my yz 125 2001 crank case

You know aluminum can be welded very successfully now, so best bet is to remove that case and take it in to a good welder..You can ry the quick fix (JB Weld) is what i recommend, but success is rare !....good luck to you my friend...Tim

SOURCE: 2006 Yamaha TTR 50E pouring oil out of air cleaner housing

With the oil problem I read on another site that Yamaha did that so that excess oil would be burned up in normal running (but this was usually smaller amounts). Anyways they disconnected the tube going to the air cleaner and had tied up in such a way that any excess oil would land on the chain thus lubricating it. But if you have that much oil coming out it could be that you have put in too much.

SOURCE: bike will not start or stay running on a full

sounds like the problem is your battery is not charging when you are riding. The most common cause is a faulty regulator / rectifier. Contact a motorcycle wreckers for these parts, or your yamaha dealer.
Easy way to test is, when your bike is running, and the lights start to dim, before the bike shuts down, using a volt meter, test the voltage at the battery terminals, should be about 14V. If faulty rectifier,no charge going in to your battery, then the reading will be low, about only a few volts. If you dont have a volt meter, then any mechanic shop can do this test for you. best to have this done before buying any parts.