Motorcycle Repair: 1970 shovel, vent tube, oil tank

Question
QUESTION: Ive got a 70 shovel of a friend of mine and  its puking out about a quart of oil out the vent tube every time he goes to fire it up. as well I think it has way too much pressure going into the oil tank. All the lines are hooked up proper and the oil pump is timed properly. He just had this motor totally rebuilt, has 60-70 miles on it.

ANSWER: Is this a Sportster or a big bike? reason I ask is you said the oil pump is timed
Mike

---------- FOLLOW-UP ----------

QUESTION: Inside the cam gear casing is the pinion gear, cam gear and oil pump breather gear which have timing marks on them and are all lined up to each other properly. I find it has way to much pressure in the vent tube from engine case. What do you think.

Answer
the pressure is created when the piston moves down.
What is happening is the oil pump has a check valve in it. Since the oil tank is higher that the motor, the check valve keeps oil from entering the case when the motor is not running. the check valve is a ball and spring on a seat. over time the seat get some carbon on it or the ball is pitted and lets oil weep into the case. What you need to do is remove the ball and spring, check the ball for damage and replace it as needed. you can also install the old ball and lightly tap it with a hammer and pumch to reseat it into the seat and then replace it
Good luck and happy riding
Mike