160 Monza Jr. oil capacity

[DucMonzter]

I'm trying to determine the correct amount of oil to add to my 160 motor. After fully draining, I attempted to add oil through the dipstick extension tube. Somewhere around 1.5L, oil began to overflow the tube. I was expecting the sump to take more since Mick Walker's book gives the capacity at 2.1L.
Is it possible that some oil was still trapped within the engine that did not drain? Is the 2.1L capacity correct? I can add more oil through the clutch inspection cover but do not want to overfill. I've read through other posts regarding oil capacity but could not find a definitive answer that would apply to this engine. Any help would be appreciated.

I was somewhat hesitant to rely entirely upon the dipstick as a level indicator since I added the extension tube and dipstick while restoring the bike. When I acquired the motor, the oil filler hole had a plastic plug with without a dipstick.

Thanks,
Jeff

[Duccout]

I wouldn't add any more oil, as you say you do not wish to overfill. When draining the oil, it is a good idea to lay the bike over to the side so as to drain as much oil as possible. Have you started the engine and let the oil drain back to the sump and checked again? You may find that the level has dropped.

[ducwiz]

I'm not a specialist for the 160 or other n/c singles. But I can post a snapshot from the uswer manual:

Snap 2020-11-09 at 19.46.40.png

Hans

[DucMonzter]

Thank you both for your quick replies...

While draining the oil, I leaned the bike over toward the filter hole until no more drips would come out. After adding new oil to the top line on the dipstick, I ran the engine a few minutes and re-checked the level. It went down slightly, but not nearly enough to allow the published 2.1L capacity. I recall learning somewhere that these engines trap oil in internal compartments and cannot fully drain. Could this possibly explain the discrepancy in capacities?

Jeff

[Buster]

Hi Jeff,
when draining the oil lean it over to the pushrod side first and allow time for oil to pass down the bevel side to the sump. Then lean it over to the drain plug side. Repeat until no oil drains out.
Phil.