I started noticing this after I adjusted the valves, but I wasn't riding it much prior to that.  A month ago I changed the oil and filter, and I've since verified that the oil level is fine.  What could be causing this?  The bike now runs great, but I'm afraid to ride it until the oil issue is sorted out.

Quote from: Juan1 on April 30, 2012, 09:47:26 AM
I started noticing this after I adjusted the valves, but I wasn't riding it much prior to that.  A month ago I changed the oil and filter, and I've since verified that the oil level is fine.  What could be causing this?  The bike now runs great, but I'm afraid to ride it until the oil issue is sorted out.

Light means low oil pressure....not low oil....

Cookie

could be a problem with the oil filter. possibly dirty or installed wrong causing low oil pressure.

Curious, what out did you use?

Michael

I used Rotella, 15W40.  Looks like I'll be cleaning an oil pressure sensor in the near future.

The oil pressure sensor id just under the ignition advancer. Make sure the problem is the sensor cos if it is oil you're screwed ...
Cool.
Buddha.

Took out the sensor, started it, and let it run under its own power for about 5 seconds.  Oil was pumping out, so I'm at least getting some pressure.  Then I re-installed the oil sensor/plug and let it idle for a while.  The weird intermittent red light returned, which is always remedied by throwing the bike a few extra RPMs.  I jiggled wires, but that didn't change anything. 

Looks like I need to take it to a shop to see if the sensor itself is the problem, or if it is the oil pump.

Also check your filter is the right way in or correctly mounted. And like the others said, check the ops.

Just get a new oil pressure switch. Doesn't cost much and this way you'll know for sure it's the switch and not oil or pump. Those switches are pretty flaky on cars(lasts 6 years) and short out after a while.
Bought one for the car for $7, Suzuki ones look like around $25 but you might find one cheaper else where( after market). All it does is get a certain psi and flips a switch. So long as fits and sends same voltage/closes switch, you're good with other brands. But: YMMV.

1. Check the oil filter
2. Drop the oil pan and look at the sump screen filter.

In investigating Junior's problem, I read there is an oil pressure relief valve inside the engine. Someone maybe could explain that further and what symptoms are if it is defective.

Possible the oil sensor wire somewhere is shorting to the frame. Check it all the way to the indicator lamp.

I agree with BaltimoreGS and jester on using the 89 bottom end and junior's known good top end.  In you free down time you could always do a top end rebuild on the old 89's top end, and crack junior's old bottom end and see what you can do for a learning experience.  Selfishly, it would be fun to watch your progress on both.  It will be cool watching you get Junior back up and running in any case.