• Routing Oil Lines for an Oil Cooler
• Running Copper Oil Lines

Click on a pic to enlarge:

The OD of the oil & vent lines is as important as the ID. ¹⁾
If you buy automotive lines that are larger OD, they will be difficult to run in the limited space and easy to kink.
The oil lines are 3/8“ ID X 5/8” OD.
The vent line should be a 1/4“ ID, 1/2” OD black rubber hose.

This tank is pretty straight forward. ²⁾
Top (2) fittings are vent and fill.
Bottom fitting is supply to the engine.
It also has no drain fitting.

On this one (74 XLH), the vent is higher than the feed and return lines. ³⁾

The oil filter (HD 63782-80T) is the small one that is usually used on custom bikes. Chrome or black can be found. ⁴⁾

It is also commonly known that the more oil you hold, the more motor heat can be transferred to dissipate that heat.
Race bikes have huge oil tanks for that reason. ⁵⁾
If you go the filter route, be sure to purge the lines by bleeding the pump front nipple first while running.
Then take the return line and place it into a pail before you connect to the barb tank fitting so you assure a complete circle has been made.

Oil Line Routing 6)

74 XLH Oil Filter Plumbing 7)

Early Sportsters had the lines route to the top of the case. ⁸⁾
Later the MoCo routed a line directly to the back of the oil pump.

There is a transmission vent on top of the case in the area near the starter solenoid. ⁹⁾
This one should just vent to atmosphere, either up attached to the frame, or down aimed to ground.

Oil line connections on a 67 model 10) 1- Return to tank, 2- Supply to motor, 3- Vent hose 11)

Oil lines on a 74 XLH 12)	Oil fittings on a 75 custom 13)	Oil lines on a 75 XLH 14)