Commando 69 oil return

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pierodn

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Hi All.
We must attempted to the first start after the engine rebuilt.
Oil is in the tank with a lot of kicks of the start lever without spark plugs.
100 gr. of oil injected from lower timing oil feed banjo.
How many time needs to the oil to return into the tank after the first start?.
Thank you.
Piero
 
2 to 3 mins depending on the prime plus if an oil filter is fitted, if you pour some in the rocker boxes the sump will have oil in and the cam will be wet so even less.
 
After a complete oil change, sump drained/strainer cleaned, it took 2 or 3 minutes of 1k rpm idling before seeing anything out the return line. This was with oil filter about half pre-filled with oil. I have a pressure guage fitted and like always it showed full 55 psi immediately upon start up. I'd say it's a fools errand trying to get a return by just kicking.
 
I just did this to a Norton today! Changed timing cover and oil pump. With plugs out , I kicked it over maybe 25/30 times till oil returned. You can hear the bubbles coming out of the return. I would NEVER attempt to start an engine until I saw some oil return
 
About 150 kicks maybe more if you rebuild an engine, have a low placed oil filter on the return line, and forget to fill the crank back up before assembly (ask me how I know). The oil pump has to fill the crank back up first before the pressure is up enough to get return oil. That's my theory anyway. Takes a long time with the kick start. Hopefully you used some good assembly lube, and squirted oil on all the rotating parts top to bottom before starting the plugs out kicking. If just changing oil and filter on a used motor, 25 to 30 kicks as mentioned should/can get a dribble at the return tube in the oil tank.
 
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Oil return to the tank only tells you oil has made it to the crankcase - it does not tell you whether your oil is actually getting to all areas of your engine, which an oil pressure gauge does for the most part.

Case in point - when I bought my Combat, it had sat since the mid 70’s with a fresh rebuild, since the top end had grenaded on the previous owner. Kind of strange for a Combat to go south that way, but whatever - super blends were put in at the time, so all good. As part of my restoration of the bike, I decided to put an oil pressure gauge on the bike. First start, oil pressure = 0!!

Oil was returning to the tank, actually A LOT of oil was returning, including through the crank vent hose…. hmmm…

Pulled the timing cover - pump checked out, as well as the output rubber to the timing cover. After much looking and head scratching, I noticed that the blanking plug in the timing cover that blocks the cross drilling between the main gallery and the oil pressure relief valve was absent - no staking marks, nothing!! From the factory this way!! No wonder the top end went south…

I have been a firm believer in having an oil pressure gauge on a Commando ever since.

FWIW
 
Please I don't want to turn this into an argument but, if you properly prime you new rebuild, 4 oz. in sump, pump the crank as full as possible, Fill you oil filter, fill your oil tank. you should get oil return in 25/30 kicks. If you are running this engine for 2/3 minutes without return you are damaging something in that engine!! IMHO
 
Derek Wilson said:
Oil return to the tank only tells you oil has made it to the crankcase - it does not tell you whether your oil is actually getting to all areas of your engine, which an oil pressure gauge does for the most part.

Case in point - when I bought my Combat, it had sat since the mid 70’s with a fresh rebuild, since the top end had grenaded on the previous owner. Kind of strange for a Combat to go south that way, but whatever - super blends were put in at the time, so all good. As part of my restoration of the bike, I decided to put an oil pressure gauge on the bike. First start, oil pressure = 0!!

Oil was returning to the tank, actually A LOT of oil was returning, including through the crank vent hose…. hmmm…

Pulled the timing cover - pump checked out, as well as the output rubber to the timing cover. After much looking and head scratching, I noticed that the blanking plug in the timing cover that blocks the cross drilling between the main gallery and the oil pressure relief valve was absent - no staking marks, nothing!! From the factory this way!! No wonder the top end went south…

I have been a firm believer in having an oil pressure gauge on a Commando ever since.

FWIW
Click to expand...
Hi.
Why "oil was returning, including through the crank vent hose"'.
Thanks.
Piero
 
pierodn said:
Hi.
Why "oil was returning, including through the crank vent hose"'.
Thanks.
Piero
Click to expand...
On the 2XXXXX series motors, the crank case vent is on the back of the crankcase, down low. So, if the engine wet sumps, it will return oil to the tank through the crank case vent. As there was no restriction in my oil pump flow, and no oil was being by-passed through the oil pressure relief valve, my engine was basically wet sumping while it was running!!
 
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