1972 CB750 Chopper

[HOLLzYWOOD]

I recently bought this 1972 CB750 Chopper bored out to a 8: 35 while riding the bike oil comes out of the tank cap there is no dipstick this is a aftermarket tank I was wondering if anybody could tell me why this is happening I change the oil out of the motor and drain the tank and added 3 quarts I have read it takes three and a half to 3.7 quarts but I only put 3 to see if it would still happen and it did any information would be helpful and useful thank you.

 

[dirtdigger]

oil capacity is going to depend on the size of the oil tank. Is there a vent in the oil tank and or a vapor return line? You have to vent the tank somehow. Cant really check oil level in the tank either without some sort of dipstick. Guessing it is a round type oil tank.

 

[HOLLzYWOOD]

I dont think there is a vent line . There are 3 lines. 1 a small line going to the back of the motor and the other 2 going to the right dack side of the motor. The tank is under the seat and has the battery compartment built into it. When i changed the oil it was almost full with 2 1/2 quarts. The tanks shape is like an octagon. Since there is no vent could it be building to much pressure. Could one of my return lines is collapsing when being riden.

 

[amc49]

You MUST vent that tank.