Topic: Oil light keeps turning off while trying to start bike

[Nstillwell]

I'm so confused. I just went through my carbs, clean them and reinstalled everything. Now the bike won't start. It sounds like it wants to. The oil light is also acting weird. It turns off when I hit the starter. Then it stays off for like 30 seconds. Turning the key on and off doesn't have any effect. Then after the about 30 seconds the oil light turns back on again. Until I hit the starter again. Then it turn off. It also turns off when I try to kick start it. What would cause this? I'm guessing the coils are also dead when the oil light turns off. But I haven't pulled the gas tank off to check if they are getting 12 V when the key is turned on and the oil light is off yet. It was all working fine before I pulled the carbs...

[Kevnz]

I'm guessing that your oil pressure is building up as the engine spins, either by starter or kickstart, and takes a while before it drops off again. Nothing to worry about, unless the light doesn't actually go out.

[TwoTired]

The oil light is controlled by a pressure switch, if the oil pump makes pressure (over 5-7 psi) and the key switch is on, the oil light should go out when the oil pump spins.  As it is connected to the crankshaft, either e start or kick start will spin the pump.  If you have enough oil in the sump, the pump will make pressure in the oiling galleries.  After some time of not spinning, the pressure previously built up slowly bleeds down below 5 psi.  The light should warn of this condition.

If you suspect ignition power is not there, check the bar control off- run- off switch, and position it in the run position.

[Don R]

 And the coils should be powered when the key is on whether there is oil pressure or not. Sometimes the quickest way to get oil pressure is a quick engine start.

[rotortiller]

You may have a weak oil pressure switch and it's going off at minimal pressure. The light should come on when the engine stops turning. Normal bearing clearances etc will not contain 5psig (static) in the oil gallery for 30 seconds. Try another switch or put a pressure gauge on it if you want to know.

[PeWe]

Oil level in oil tank OK?

[HondaMan]

You may have a weak oil pressure switch and it's going off at minimal pressure. The light should come on when the engine stops turning. Normal bearing clearances etc will not contain 5psig (static) in the oil gallery for 30 seconds. Try another switch or put a pressure gauge on it if you want to know.

I've found that with bearing clearances at 0.0008" across the crank/rods and using (cold) 20w50 oil, it will act exactly like he is describing: the pressure in the main galley stays high for quite a while!

[TwoTired]

Wonder if the op changed any carb components when he “cleaned the carbs”.  Might contribute to the no start issue.

[rotortiller]

For reference I just timed my dead cold engine oil light at 52F/11C. Five seconds after the engine stops the light comes on. Seems similar in time with a slight delay even when warm. Obviously yours has changed the delay for some unknown reason, otherwise you would not be asking the question. That being said I doubt it's related since the neutral light and other stuff is still powered. Checking the plugs for spark is easy with a spare plug. I would look at the recent work done on the bike and start with the carbs by looking to see if the plugs are wet, choke is working correctly, float bowls are full etc and chase down the gremlin. Might be something simple hopefully. Something as simple as disturbing an ignition wire under the tank could sprout havoc.

[Nstillwell]

You may have a weak oil pressure switch and it's going off at minimal pressure. The light should come on when the engine stops turning. Normal bearing clearances etc will not contain 5psig (static) in the oil gallery for 30 seconds. Try another switch or put a pressure gauge on it if you want to know.

I've found that with bearing clearances at 0.0008" across the crank/rods and using (cold) 20w50 oil, it will act exactly like he is describing: the pressure in the main galley stays high for quite a while!

The oil light is controlled by a pressure switch, if the oil pump makes pressure (over 5-7 psi) and the key switch is on, the oil light should go out when the oil pump spins.  As it is connected to the crankshaft, either e start or kick start will spin the pump.  If you have enough oil in the sump, the pump will make pressure in the oiling galleries.  After some time of not spinning, the pressure previously built up slowly bleeds down below 5 psi.  The light should warn of this condition.

If you suspect ignition power is not there, check the bar control off- run- off switch, and position it in the run position.

Really appreciate the insight and help! I assumed the oil light turning off was an electrical gremlin and since it was right next to the coils that they weren't firing. I was wrong on both assumptions. The bike actually does maintain the oil pressure in the engine for that long. And after checking the coils, they had a constant 12v to both coils.

Put a new battery in and she fired up! The bike seemed like it was turning over fast enough to start with the old battery but it started right up with a new battery. After completely disassembling the carbs, sonic cleaning everything, throwing away junk pods in favor of a stock airbox and rejetting to factory jets, I was so nervous that I missed something. It ran perfectly though on my first ride this evening. Thanks much all!

[Kevnz]

Good result.

[Bodi]

The oil filter housing traps some air above the outlet level. That's compressible, and acts like a spring keeping the pressure up for a while. As the oil flows through the crank bearings the air bubble expands and the pressure drops.
So I would e happy that the bearings are nice and tight!