I restored a 1973 rt3 360 enduro Yamaha picture attached.  The bike is running great its really dialed in, I am having issues with the oil pump, very very small bubbles coming from the pump to the cylinder. The pump has been rebuilt, new banjo bolts, new copper crush rings, inspected all fittings can no cracks, new oil lines from tank to pump and pump to cylinder, new clamps. Bubbles appear sporatically from the pump to cylinder and as the bike heats up they increase.   I think that when I rebuilt the pump it is possible that one of the new seals was bad.  I am interested in knowing if anyone else has experienced this and am looking for input. Would appreciated any comments or ideas from any one who has experienced this. 

Your problem is the wrong size wrong type (clear hose). when the engine gets hot the incorrect hose will expand at the fittings and you will get air in the lines. Get rid of all the aftermarket hoses and install OEM Yamaha black hoses and clamps from the oil tank to the pump and from the pump to the cylinder fitting. Problem solved.

Yamaha OEM hoses have a certain size I.D for a good reason. Make sure you use Yamaha OEM clamps too! 

The outlet end of the line to the cylinder is an open line through the union & with the motor inlet sucking & blowing back i guess there's got to be some bubbles in there.
Use original right size black line & you won't see it--Umm, even if they are there.
If ya dead set on staying with clear, i get a chainsaw mixture of different small size semi-clear [for my chainsaw & weedeater that cost next to nothing from Aliexpress etc.
Seems good quality & goes around corners without kinking.
I'm not convinced the pump is ever totally air free, even after bleeding.
But the pump bits are lower down where it gathers the oil into the shaft to send to the cylinder than the where the bleed screw is, so its a bit of a compromise is my guess.
Here's an example although might be for individual size purchase but multi sizes together are out there somewhere.
www.aliexpress.com/item/1005012479642552...d%3A1005012239820728

Seems like I read somewhere that anyone who uses clear tubing sees bubbles, so if they bother you, go back to opaque 

I had a 1978 DT175 with clear tubing and no bubbles until the pump failed.  Luckily, I saw the bubbles when I looked down while riding.  I always carry a small container of 2-stroke oil just in case the pump fails.  I added to some 2 stroke oil to the gas tank and rode straight home.  I rebuilt the oil pump and bled the oil supply line.  The next time I went for a ride, there were no bubbles in the clear tubing.

CDR,

Not all clear tubing is the same. if you happen to get some that is close to the Yamaha oem I.D. black hose with good clamps and good at withstanding heat it most likely will not expand enough the draw air creating bubbles or air in the lines.

It's the oversize loose fitting clear line most people use with terrible clamps that have the problems.