Interesting oil level check

[mo8414]

I have been waiting on brake pads to come in the mail so I haven't been riding my bike for 3 or 4 days. The other day I decided I was going to check the oil then see how long it took for the level on the dip stick to change from what the level actually is to gage how long after checking the oil you have to accuratly read the oil level.

Normally when checking the oil I go for a ride right after so the oil the next day is always about an inch higher than it is once you do the oil check procedure.

This time, I never road the bike after checking the oil this time due to waiting on the brake pads to come in. I noticed the engine oil never changed from the level it was after doing the oil check procedure. Next day, still the same. Start it and do the oil check for a second and third time days apart and the same result.

Last night I changed my brakes, checked the oil then went for a ride. This morning I check it before running it and its back to being about an inch above the level it is after doing the oil level check procedure.

The next thing I'm going to do is check the oil. Then let the bike fully warm up then shut it off without reving it or riding it then see where the oil level is in the morning. Only thing I can think is the bike getting warm pushing more oil into the chamber where the dip stick is and fills it up higher until its ran again and comes back down to normal. We will see.

All this to say, it seems if you only do the oil level check procedure on a cold engine, the oil level will stay the same indefinitely and adding more oil shouldnt require you to do the procesure again to read an accurate level.

 

[atomsplitter]

The oil level you are reading is in an oil tank, not the engine's sump, so actual oil level isn't critical. The Rocket (both Gen's) have a scavenging pump that returns oil from the sump to the oil tank. These pumps have relief valves to limit the maximum pressure because they are both positive displacement type pumps and discharge pressure and flow are speed dependent. When you rev the motor the oil pressure goes up until the relief lifts and when the engine idles the reliefs usually shut. Additionally, both Gen's use a check valve to prevent oil from the tank backfilling the sumps on shutdown, however one-way checks are notorious for leakby so the only way to accurately measure the oil quantity in the system is to start the motor and have the scavenge pumps (it's double ended) return any leakage to the tank. So, it's not surprising if the oil tank has an oil level under one set of conditions (bike ridden) and a different one under another (bike idling or no load only) (at least to me).

 

[A1A Rider]

Would you advise then how to measure correctly?

 

[Rockatansky]

Would you advise then how to measure correctly?

Let's say it like this: in former times somebody would have written "RTFM".

- cold engine, keep it on the side stand
- start the engine and let it run for 60-90 sec
- don't touch the gas - no idle!
- switch it off
- wait min. 3 min.
- measure

You do it different? Your measurement is worth nothing.

 

[A1A Rider]

- don't touch the gas - no idle!

no idle?

 

[Rockatansky]

Ah, sorry - it's not "no idle", but "only idle"... in any case do not play with the gas, this would influence the level.

 

[mo8414]

Let's say it like this: in former times somebody would have written "RTFM".

- cold engine, keep it on the side stand
- start the engine and let it run for 60-90 sec
- don't touch the gas - no idle!
- switch it off
- wait min. 3 min.
- measure

You do it different? Your measurement is worth nothing.

After doing this procedure, if you need to add oil you can add more and check it without going through this procedure again.

 

[Claudiu]

There is a "barrel" in the crankcase in the middle of the engine. When parked, your oil puddles in the sump. When you start the engine, the oil pump stage1 is collecting the oil from the sump to fill that barrel, separate bubbles, etc. Then oil pump stage 2 is pulling from that always full barrel and lubricating everything. The concept is similar to aircraft’s engines so you can fly upside down. Similarly, a shallow but big engine like R3 would work dry every time you brake or accelerate and you would have oil everywhere but in the pump. The oil check should be done after running the engine just to be sure your internal barrel has enough oil.

So the strict timing, rpm, etc. are not important. The manual had to say something to people. Just start the engine, let it 1 minute to fill the barrel, stop it and check if there’s enough oil in it. Wait to long and the oil is slowly leaking back to sump.

 

[Gregger]

The main point is to try and check the level the same way every time. This should give a relativly consistant reading. It's close enough.