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Discussion Starter · #1 ·
I occasionally get an oil light when the engine is cold and the RPM has exceeded about 3k.
I want to check the pressure with a gauge.
Does anyone know the thread size of the sender?
Kawasaki made an adapter (57001-1033) for their oil pressure gauge (57001-164) but I can't find the thread size for those either.

Does anyone know what PSI the switch is supposed to switch at?

The manual specifies 43-51 PSI at 4000 RPM with 90 C degree oil.

I haven't experienced any symptoms of low oil pressure. It only happens when cold and I accidentally get the RPM too high. Coming back to idle, sometimes it goes off after a second, sometimes it takes a crack of the throttle for it to go away. I never see the light once it warms up.
 

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I remember running into British pipe threads, BPT, when I changed the oil switch, but don't remember exactly which part.

I believe the switch is 5-7 psi.

If the oil is still cold, it's probably experiencing the air entrainment phenomenon that this engine has. It goes away after warmup.
 

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Discussion Starter · #3 ·
Thanks!

If the oil is still cold, it's probably experiencing the air entrainment phenomenon that this engine has. It goes away after warmup.
Is this something I need to be worried about? I try to be SUPER gentle while it's still cold to avoid the issue.
The manual shows the pressure switch reads right at the base of a T intersection as it heads up to lubricate the valvetrain.
I don't want to cause excess wear.
 

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Thanks!



Is this something I need to be worried about? I try to be SUPER gentle while it's still cold to avoid the issue.
The manual shows the pressure switch reads right at the base of a T intersection as it heads up to lubricate the valvetrain.
I don't want to cause excess wear.
Probably not, mine did the same thing. I didn't think about the air entrainment until I was reading your post. The blinking oil light was discussed quite bit a few years ago. Honestly, I don't think there was anything wrong with the old switch.

I just tried to always get it warmed up before taking off, not full temp but just getting the gauge moving.
 

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Discussion Starter · #5 ·
Probably not, mine did the same thing. I didn't think about the air entrainment until I was reading your post. The blinking oil light was discussed quite bit a few years ago. Honestly, I don't think there was anything wrong with the old switch.

I just tried to always get it warmed up before taking off, not full temp but just getting the gauge moving.
Ok. So there really isn't anything I can do maintenance wise to prevent this? Just more careful riding and more warmup time?

For noise reasons, I don't like to let my bike sit running in my driveway. My driveway is such that, my house and garage and my neighbor's house and garage form an acoustic funnel. It reverberates off all the buildings making a debaffled bike that much louder. But I don't want to cause engine damage.
I've never had it happen once the needle comes off the coldest stop.
I still am gentle until it's plenty warm.

Here's the oil path after the pressure switch, from page 6-3 in the service manual.
It looks like it dumps oil on top of the cams and it basically gravity feeds down onto everything.
"17" is called an "Oil Reserve". That implies it really only needs flow and not pressure to lubricate the top end.
Even a momentary lack of oil might not be noticeable if the "reserve" was previously filled.

As I'm looking at this diagram, now I wonder if I assembled something wrong in the heads and starved the front top-end of oil.
That would be enough to seize a valve and snap it off into the cylinder after about 10 miles....
I wish I had looked for that when I took it apart post accident. There probably would have been signs of scoring on the cams.
Maybe some RTV blocked the oil line. That's been a mystery to me.
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Ok. So there really isn't anything I can do maintenance wise to prevent this? Just more careful riding and more warmup time?

For noise reasons, I don't like to let my bike sit running in my driveway. My driveway is such that, my house and garage and my neighbor's house and garage form an acoustic funnel. It reverberates off all the buildings making a debaffled bike that much louder. But I don't want to cause engine damage.
I've never had it happen once the needle comes off the coldest stop.
I still am gentle until it's plenty warm.

Here's the oil path after the pressure switch, from page 6-3 in the service manual.
It looks like it dumps oil on top of the cams and it basically gravity feeds down onto everything.
"17" is called an "Oil Reserve". That implies it really only needs flow and not pressure to lubricate the top end.
Even a momentary lack of oil might not be noticeable if the "reserve" was previously filled.

As I'm looking at this diagram, now I wonder if I assembled something wrong in the heads and starved the front top-end of oil.
That would be enough to seize a valve and snap it off into the cylinder after about 10 miles....
I wish I had looked for that when I took it apart post accident. There probably would have been signs of scoring on the cams.
Maybe some RTV blocked the oil line. That's been a mystery to me.
View attachment 54253
I'm pretty sure I've seen the light briefly on warmup since replacing the switch, so warmup is probably all you can do.

Some of the oil in the top (number 20?) will be pressurized to keep the lash adjusters pumped up. So if you actually lost all pressure, you should hear the rockers tapping soon after.

I'm recalling the light just about as you described, about 2 nd or 3rd gear it would light up.

There was one time the light came on and stayed on, because it had an oil leak and I hadn't checked the oil. The leak was on the right side case above the starter. It's somewhat common to find the gasket pushed out there. Maybe that way since assembly at the factory? I've seen three like that.

One way to warm up quicker is to turn the choke off ASAP, lean equals hotter combustion. In your case you might make a timing profile specifically for warmup.

Give you a nod for being considerate of the neighbors, they don't know how lucky they are.
 

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Discussion Starter · #7 ·
One way to warm up quicker is to turn the choke off ASAP, lean equals hotter combustion. In your case you might make a timing profile specifically for warmup.
I did just that :geek:
Well, back in March I set up a 2nd timing table.
I updated the 1st post to reflect the changes, with all the numbers shown relative to stock timing.
It runs 10 degrees retarted from stock, holding the RPM at 1500 with the choke on.
I still have a second switch setup to subtract another 10 degrees.
Sometimes I turn this one on as well, once I'm moving. It feels like I'm ridding with the brakes on!

The 2nd table retains stock timing at full throttle in case a road hazard requires me to accelerate.
I considered a soft limiter by retarding timing excessively above some RPM, but I'd hate to hit that limit when I need to get out of the way of something.
 

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I guess you can check the color of the oil when the light comes on, if it's milky looking you know it still has the air entrainment.

I think the sight glass is almost empty when it's running, so probably have to shut it off to check.

If I'm remembering the above correctly, that would be a way to know if it's pumping oil. Full sight glass while running would mean it's not pumping.

I think that's right, because you can watch the glass fill up after shutting the engine off.
 

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