new 1987, Oil light on at idle, 1200-ish RPM ?

[CallMeTim]

After 5 miles or so it'll idle at 1200 or so, oil light lights up.
I hold the throttle at idle so It doesn't go below 1400. Its getting a checkup at the mechanic soon. Not idling happily until really warmed and then with throttle input is one issue. Is the oil light at 1200-ish meaningful?

Thanks!

[Bob_Roller]

First, no offense meant, but you are certain it's the oil light, not the GEN light .
This mistake has happened before .
If it is the oil light, I would park the bike until you get it figured out, the light comes on at a very low pressure .

[Barry]

Agree with Bob. It could be the gen light but if it really is the oil light then you have a problem because the oil pressure at an idle speed of 1200 RPM would normally be at least 3 times higher than the pressure switch setting. No way should the oil light be coming on as the oil won't even have reached full operating temperature after only 5 miles.

[mrclubike]

Oil light on at 1200 rpm is not good
Read up on the "2000 dollar Oring"
Just Goggle it 
Hopefully all it is a improperly installed Oring and oil filter 

[Tony Smith]

Hopefully all it is a improperly installed Oring and oil filter 

One fault that haunts post 1981 engines is that BMW stopped staking the location pin in the front bearing carrier. The first sign of this fun outcome is loss of oil pressure.

Look in the sump and see if there is a small metal pin floating about in there. If so and you are quick you may get away with having the crank polished and replace all bearings - and fit a new oil pump because relative to what you are spending, the cost is minor.

I sincerely hope it isn't this of course.

[Matt Chapter]

Regarding the 2k$ o-ring, I did an oil change in the past couple of years and goofed the order of the shims and whatnot.  The symptom was the oil light coming on at idle.  A redo of the filter installation solved the problem.

Another cause of the oil light to come on during idle (or hard braking!) is low oil level.  If you're leaking, be sure to check the oil level often.