Intake valve chamber oil drain hole

1974 850 MK II. Just wondering how much, if any, oil should pool in the bottom of the intake valve chamber. Bike has been stored since the Fall on centre stand. I know there is a drain hole in the chamber on the right side but I’m not sure if the drain hole is designed to drain oil completely from the intake chamber or if it is designed so that there will always be some residual oil left in the chamber.

WEM said:

1974 850 MK II. Just wondering how much, if any, oil should pool in the bottom of the intake valve chamber. Bike has been stored since the Fall on centre stand. I know there is a drain hole in the chamber on the right side but I’m not sure if the drain hole is designed to drain oil completely from the intake chamber or if it is designed so that there will always be some residual oil left in the chamber.

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One the center stand most will be drained. The hole is at the back right behind and to the outside of the timing side intake valve. Not really a designed thing as a little oil in the area doesn't lube anything - the ends of the valve guides are well above any remaining oil.

On the side stand a lot will remain, especially on the drive side.

I found mine was a little plugged up with some gasket compound that had previously been used on the valve cover(s). I cleared it using a wound guitar string poked through the drain. I found a blob of the stuff on the oil pump screen next oil change.

You can remove the inlet rocker cover and add a bit of oil into the chamber and time how long it takes to drain. The hole is around the 5 O'clock position partly covered by the valve spring seat if i recall correctly.
You can poke a wire straight down the hole all the way to near timing chest where it takes a 90 degree bend. Try some air or WD40 spray through to check it is clear. Retest your oil drain time.

Having done this when rebuilding my engine some years ago, if you pour some cold oil in the chamber, the drain time will be
v e r y....s l o w...... You will wonder how oil ever gets out of there when the engine is running! The answer is two-fold: hot oil AND the proper orientation of the rocker spindles ensures that not all that much oil is really dumped there. IF the spindles are reversed, the drain hole cannot accommodate the feed and the valve guide/seal will be submerged in oil when running.