Bonneville America Forums Forums Technical Forums General Tech Oil Light at idle

OK this is the second time I've noticed this. After a ride of varying speeds / RPM's about 25 miles to work, I notice that my oil light comes on, but only at idle speed. So, if I pull the choke 1/2 way or otherwise get the RPM's up above 1,300 or so, the light goes out. But when I let off and bring it back down around 1,000 RPM's the light comes back on.

The first time I noticed it, I let it sit in the parking spot and went back several hours later - oil level fine, started up fine and rode home the whole way w/o incident.

Any ideas? Seems like if it was just a sensor that it wouldn't be dependent on engine RPM's. Is this RPM indicator a classic symptom of one particular root cause, or another?

Mostly, I'm worried whether I should be riding it back home tonight.

I would recommend you check the oil pressure with a gauge ASAP! Could be a bum sensor, but why chance it?

If the sending unit is bad it could depend on RPM. It could take some extra pressure to kill the light. I would check pressure with a gauge before you ride it anymore though. This is similar to why I made oil pressure gauges for our bikes. Wendy washed her bike one time and got the sending unit wet causing the light to stay on. That worried me since I had no idea if it was an electrical problem or the actual low pressure in the engine. Turned out it was the wet unit since once it dried out the light worked fine again but I made a gauge that week so I am sure from now on. I hate idiot lights because usually by the time one comes on the damage is done, with a gauge it is more likely to catch a change in pressure before you lose it all together. Hope your situation is something simple and not low pressure.

thanks y'all. I'm going to give it a shot (the ride home) and hope for the best. will keep a close eye on the idiot light and shut her down immediately if it comes on at speed.

If you do have an oil pressure problem, don't condemn the engine right away. A number of fellows on other forums have had loose oil pressure lines under the valve cover. Verify your oil pressure with a gauge when hot.

What viscosity/type of oil are you using and when was it last changed?

made it home OK, but alas the oil light lit up again after it sat idling in the driveway for a few seconds. guess this will be a good enough reason to replace the clutch and do the valve job again if it is pressure related. now all I have to do is figure out how the check the oil pressure haha.

If I remember right, I'm using the Motul 15/50. The local Yamazuki dealer was discontinuing their stock of it and I got the last 5 quarts.

I had a corroded wiring connection on my oil preassure sending unit that caused the same problem on my bike a couple years ago. The corosion was caused by water collecting in the rubber boot that is suppposed to protect the connection. I took mine apart and cleaned the connection. When I put the boot back on I turned it with the wire down instead of up. Have had no more problems for over 25000 miles. The bike has over 30000 miles on it now. Of course, an oil preassure test will tell all but check you wiring connection before replacing the sensor.

If you're replacing the clutch, check out the plastic oil pump gears while you're in there.

UPDATE:

I ordered all the bits and pieces for the homemade oil pressure system. While adding that I figured I would just go ahead and try everything I could think of while the oil was drained (I realize I could have added it w/o draining the oil but I just want resolution to the issue without the possibility of causing any more damage): valve clearance check since that was about due, check the sump screen, pull the clutch and pumps to inspect those, etc.

I drain the oil and get the valve cover off and go to remove the banjo bolts that hold down the internal oil feeder tube when I notice one of them is loose. I figure "great, it just came loose - problem solved!"

Nope, the sucker broke off leaving most of the threading seated in the camshaft holder. Ouch! I am sure I didn't overtorque these banjo bolts last time I did the valve clearance job, so it must have just failed.

QUESTION: I know these camshaft holders are matched at the factory during assembly, so if I screw this procedure up (in getting the broken bit of the banjo bolt out) I will be hosed. Other than being very careful by not trying to force anything, does anyone have any recommendations on how to go about this?

With the head missing off the banjo bolt the screwed part should not be under much tension, it may screw out quite easy with an extractor. I broke one of on a brake caliper once and it screwed out with a screw driver. good luck.