Air in replaced oil Iines?

Hi everyone!

I own a 72 Norton Commando (small drain plug) and was going over the whole thing, replacing old worn out parts, cleaning it up, etc. I ended up purchasing all new stainless oil Iines (from OldBritts) and an SDK Oil Pressure Relief Valve (from Classic British Spares).The lines were cracking and the oil pressure reef valve looked like it had been tampered with and I didn't trust the last mechanic. The question is with replacing all the oil Iines and the oil pressure relief valve, aren't you introducing all sorts of air bubbles into the lines and oil system? Maybe I am missing something...Old Britts instructions seem pretty straight forward with just removing the old lines and bolting on the new ones, with no mention of draining the oil system, priming, or anything like that.

Anything oil related always makes me nervous so I would rather triple check. Thanks in advance!!

Samuel Whittle said:

The question is with replacing all the oil Iines and the oil pressure relief valve, aren't you introducing all sorts of air bubbles into the lines and oil system?

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Yes, but if there are no obstructions then leaving the bike overnight will fill the lines with oil as gravity and the clearances in the pump will allow the oil to flow. You can check the next day by removing the oil pressure relief valve and then kicking the engine over with the ignition off, oil will be seen inside the cavity after a few kicks, then replace the OPRV.

kommando said:

Yes, but if there are no obstructions then leaving the bike overnight will fill the lines with oil as gravity and the clearances in the pump will allow the oil to flow. You can check the next day by removing the oil pressure relief valve and then kicking the engine over with the ignition off, oil will be seen inside the cavity after a few kicks, then replace the OPRV.

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Beautiful! Thanks for the quick reply. With the installation of the OPRV, my understanding is for it to be set to 25 ft. lbs of torque, I am assuming that is the same for both of the nuts. Setting the first and then the second into that?

kommando said:

You can check the next day by removing the oil pressure relief valve and then kicking the engine over with the ignition off

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...Or, perhaps easier, slacken/remove the lower rocker feed banjo fitting.

You can just let it wet sump. To check remove the crankcase drain plug and put a suitable container to catch the sump oil.

Best.