Oil overflow issues

I've had my Commando for six months now and it is my first British bike. I know this may be a stupid issue but I took my Mk II 850 for a run last week and I checked the oil before I went. I did not warm the bike before checking the oil and there was no oil level on the dipstick when I checked. the bike was on its centre stand.

I added a litre of oil and the level came up to the maximum on the dipstick so away I went.

About 20 k down the road oil started pouring out the overflow tube under the seat and from the oil tank.

It didn't appear to be wet sumping which I believe is oil blowing out the back of the engine where it has drained into the sump after sitting for a period. so why would the oil tank have been overfilled? Why wasn't there oil showing on the dipstick when I checked it? Sorry for the dumb question.

Frank

Your bike had wet sumped while sitting so your dipstick would have shown no oil in the tank as it was in your crank case, you should have started it up first and watch the oil return to the oil tank, when you see the oil returning let run for a few minutes before checking the oil level in the oil tank, adding new oil into the tank before the oil pump has returned the oil to tank will of course make it overfilled so the overfilled oil has to go somewhere

Ashley

I had the contrary problem, i have started without oil!!!, read my topic!!
Ciao
Piero

lawman said:

I've had my Commando for six months now and it is my first British bike. I know this may be a stupid issue but I took my Mk II 850 for a run last week and I checked the oil before I went. I did not warm the bike before checking the oil and there was no oil level on the dipstick when I checked. the bike was on its centre stand.

I added a litre of oil and the level came up to the maximum on the dipstick so away I went.

About 20 k down the road oil started pouring out the overflow tube under the seat and from the oil tank.

It didn't appear to be wet sumping which I believe is oil blowing out the back of the engine where it has drained into the sump after sitting for a period. so why would the oil tank have been overfilled? Why wasn't there oil showing on the dipstick when I checked it? Sorry for the dumb question.

Frank

Click to expand...

You unknowingly overfilled the system.
You need to read up on the basic theory/design of a dry sump system. Things will make more sense. http://en.m.wikipedia.org/wiki/Dry_sump

Best time to check oil level on any bike, is when the bike is hot.
Oil actually expands quite a bit when it is at running temperature.
Not to sure off the top of my head what the coefficient of oil is, but I'm sure someone here does.

Moral of the storey, always check oil level when putting the bike in the garage after a ride. ( plus your periodic trip checks )

Cheers...... 8)

I live and I learn and I like the tip about checking the oil when putting the bike away.

Frank

And leave jugs up near TDC to lessen rate of oil seeking its source. Least ya know the pump is good to go, got a hillbilly oil change and an idea of the time it takes to pump a quart or more. It takes a while to learn Commando quirks so more lurking as it either endears you or makes ya set it aside for decades...

Thanks Hobot,

I don't give up I just learn.

Frank

Its more ' Drain Down ' than ' Wet Sump ' .

Running itll empty the sump into the tank . Not necesarilly pump it out the pipes .
You can have a kinked return pipe or obstruction cause improper draining of the case running , where it will discharge it whereever it can . Hence the smoke .

A puff on start ups not unhealthy , for the machine at least , as its ' Lubeing itself ' .

Theres a oil consumption thread elsewhere . Youre unlikely to use a half litre every 1000 miles unless you thrash it . Best to check level AFTER the Ride previous .

You could get oil dilution and burn of of the petrol content then on a long ride . Such as a vehical pottered around daily for a month or two - then taken for a few hundred mile spin -
Appearing to use a half litre . After the dilutions boiled of , the consumtion ceases . Ordinary consumtion MIGHT be 200 Mls per 1000 to 200 Mls per 5000 on a tight motor .

A overhauled motor with regular oil changes & never taken past 6000 rpm , well maintained ( and the rocker / valve angle right ) should pass 50.000 before it burns any .
Provideing the Air Filters good .

"It didn't appear to be wet sumping which I believe is oil blowing out the back of the engine where it has drained into the sump after sitting for a period."

It doesn't always blow out the back of the engine.. most times it simply pumps back into the oil tank and all is well. By adding oil, it was over filled. Just think of the oil pump as a leaky valve.. gravity leaks the oil from the tank (higher) down through the pump into the crankcase. Some are worse (faster leak down) than others.
You DO want to make sure the inlet screen in the tank is covered before starting, so the pump doesn't suck air. If it is lower than the screen, a sump draining is in order (hence, the pain in the neck so talked about) to restore the oil to the TANK, without over filling the system.

Thanks for the advice everyone,

I'm pretty sure that I overfilled the oil tank. I will drain the oil and check out how much is in their.

Just another foible to deal with.

Frank