Ironhead Oil switch light comes on after short ride

[bustert]

too true, too true mr. ferrous
there were a couple of threads so many ways to do it.
if he is still around, there was a dude selling conversion for around 150 bucks off fleabay. easy to do with common shop tools and 50 bucks.
mine has nearly 200k on it but according to mr. hippy, it should have gernaded moons ago.
i showed no mercy.

[Ferrous Head]

if he is still around, there was a dude selling conversion for around 150 bucks off fleabay.

He (Tom Laflewer - wryness with sewer) was booted from here and the other site several times. Keeps signing up under a different alias. He's a thief.

[staniel]

After riding this bike for a few months and maybe 600-700 miles, I've determined the issue with the oil light switch.

What happens is I forget to turn the ignition or the enricher on the carb on (VM38). I end up kicking the bike over a bunch of times and flooding the engine. At this point I'm "oh god, what happened?? Why won't the bike start??"his poin At tt, I think enough oil has left left the tank that air starts thas entered

Ooil nce I some gas evaporate in the cylinders, I turn the enricher on and the bike starts first kick and the oil pressure switch light stays on and doesn't turn off.

So what I do is turn the bike off, pull the oil return line and kick the bike till oil spits out. I attach the oil return line to the tank tank, startbike and... voila! The oil pressure switch turns off and stays off until the next time I forget to turn the key or chokeotn. The light *only* stays on when this happens. I've gone weeks, without fsls the bike up first or second kick without the light turning on while riding. The moment I mess up the starting sequence, the light willoil on.come without fail

[rejeanprimeau]

Is your return line go to the right barb on your tank ? Worth checking.

[1Scooter]

Remove the oil pressure switch. The with a wood dowel snf s small hammer, tap the check ball with the dowel a few light hits. You have just re-seated the check ball.

[billeuze]

It looks like you are on to something and that you need not now be concerned about whether your oil pump is supplying your engine with enough oil. I don’t think you have solved why your light sometimes stays on when the engine is running. But the fact that you have identified under which conditions this happens means you are getting a lot closer.

Originally Posted by staniel

… I end up kicking the bike over a bunch of times and flooding the engine…. this poin At tt, I think enough oil has left left the tank that air starts thas entered

Ok, there is something you are not understanding. Unless your oil tank is COMPLETELY empty, attempting to start your flooded engine not drain it down to the level of introducing air to the oil pump. That would take thousands of kicks.

I see from above discussion you have a misunderstanding of the term “priming the pump”. I think you are confusing priming the pump with priming the oil system. Yes, the way our bikes are designed gravity does work to prime our pumps but will not work to prime the oil system.

Most pumps designed to push liquid (like our oil pumps) have to full of liquid in order to function. If air gets in to the pump (running the oil tank completely empty or installing new oil line for instance), it can’t suck the air through. Normally as a pump turns, the liquid in it has to flow with it because it can’t do anything else. Air on the other hand is compressible so when the pump turns the air doesn’t have to move with it, it can simply expand m. Filling the feed line with oil will get oil into the pump and it’ll start working again (it’ll start pushing oil out the other end) That is what “priming the pump” means. And gravity does work to prime these pumps since the oil tank is above the pump. As long as the hose flows downhill (or level) all the the way to the pump, gravity will prime it as long as long as there is there is an escape route for the oil. If the pump is running it escapes out the return line (I’m not saying that it will gravity prime before engine damage occurs). If it’s not running, that’s why we remove the pressure switch overnight to let the air escape.

The pump doesn’t care if there is air in the return oil path. As long as the suction line and pump body remain full of oil gravity will keep the pump primed (Unless of course the oil pump has no vent, then it’ll be like holding your finger over the top of a straw - gravity doesn’t pull the liquid out until you release you finger and allow air in the top). If there is any air in the return path the oil behind it will simply push the bubble through. The reason for “priming the oil system” is really only relevant for a freshly rebuilt motor that has dry oil passages. And actually the oil passengers will fill quickly enough once the engine starts. It’s mostly as an oil system check before starting a newly rebuilt engine - will it get oil or did I screw up and blocked an oil line somewhere or installed a faulty oil pump - that is what Ferrous Head was explaining with the rocker box oil lines.

As for moving on to what is actually going on when your oil light stays on after a botched start, sorry, I don’t have anything to add. I hope you find it sooner rather than later. In the mean time it must be re-assuring to know that your pump is doing its job

[Ferrous Head]

"his poin At tt, I think enough oil has left left the tank that air starts thas entered

These oil pumps do have a "flaw" in that there is no oil seal on the breather tower. With some pumps oil will seep past the breather shaft and into the cam cavity and drain into the cases. What we refer to as "wet sumping".

Long before your oil bag is completely emptied you will feel the result of a wet sumped engine. The combination of drag of the oil on the rotating assembly (wheels and rods) plus the increase in crankcase compression (reduced volume from the oil) will make the licking of the engine a serious problem.

[sungod]

You might want to add an oil pressure gauge to see what's actually happening.

[Ferrous Head]

It's not completely necessary to see the spurts from the oil return line in the oil .

The oil returned from the engine will be aerated.

The real check though in any case is to just pull the return line off and see what is or isn't coming out when the engine is running.

Oil light switches are electrical things. Meaning all bets are off.