As I understand it, normally the primary get oil via the Primary Chain Oiler and then the oil is sucked out back to the oil pump. This means that there should be a limited amount of oil in the bottom of the case. The primary case is also vented. Is this correct?

What would happen if the oil were to remain in the case and not get sucked out effeciently?

Also why would I want to block off the primary oil as suggested many times here in the forum?

 

If the primary is sealed correctly and vented it creates a vacuum that aids in the oil return.&nbsp\\; Only a few ounces of oil will accumulate.&nbsp\\; I've had my 72 for 36 years and probably have 250,000 miles on 2 primary chains with the stock chain oiling system.&nbsp\\; I would not recommend blocking off the chain oiler and running a wet primary.&nbsp\\; If the oil is too high gets on your clutch, too low it will melt your chain tensor and ruin your chain.&nbsp\\;
Just change your oil often.&nbsp\\; I change mine every 800 to 1000 miles.

 

Testing....

 

Filthylucre is correct, if the primary is properly sealed, the oil is sumped back out. If not properly sealed, the primary case will fill with oil and you will begin to have clutch slippage. The same oil in the engine goes through the primary, that is why many people block it off, to keep primary contaminants out of the engine system. Remember, a shovel is old technology, good, but old. I've blocked mine off on some of my shovels and run gear lube in the primary, but only did it if I had an electric start clutch hub, the teeth acted as an oil slinger. I wouldn't recommend running a dry chain.

 

the magnetic drain screw at the rear of the inner primary is supposed to keep the metal shavings (starter ring gear) from getting mixed into the engine oil as it is sucked back into the oil pump !Pretty scary HD's been doing this for 20 years + or - I did put 40,000 miles on a 1979 flh with no problems