82 GS450T my oil pressure warning light comes on at 1100rpm when stopped,fast ride.

[grcamna2]

I take a good ride on the interstate and then exit to a stop in traffic and sit at my low 1100rpm idle and the oil pressure warning light comes on.I raise the rpms to 1250 and the light goes out.This only happens after exiting the interstate..
Have any of you had a similar situation ?

[allojohn]

Low oil level? Check it...

[LAB3]

Old oil and too few rpm to pump the oil.

[Gorminrider]

This only happens after exiting the interstate..
Have any of you had a similar situation ?

No, I haven't seen this.
Since your oil pressure light is ok otherwise, and they are pretty simple devices,( switch gets "pushed" by oil; the electrical path is opened...)oil pressure must be lower. It doesn't sound at all crucial if it goes away before you start doing a lot of idling at stoplights and so on...does it?

but maybe try a different oil....if it only does it NOW, summer, the highway, ...maybe goto 20w50..

[pete]

When I first got my 450 I had a few times when that happened and I couldn't figure it out... then I learnt the correct way to check my oil level and I discovered I'd been running it low on oil.

So, just in case you're in the same situation... to check the oil level, rest the dipstick on top of the threads, don't actually thread it in. That's a significant different in oil level! Hopefully you know this already...

[grcamna2]

The light doesn't come on at all if I do local riding from town to town(50-60mph) and let it idle at(an indicated)1100rpm.
The engine oil is up to the top of the F area.
The only time it does it is after running along for an hour or more on the Interstate,gets it hotter?
I was thinking I could possibly consider replacing the oil pressure sender,possibly defective? Could I have some sediment in the pickup screen ?

[Gorminrider]

since so far, Pete is the guy who's had this, I'd top that oil right up to the line, with the bike level, (sitting on it's tires ).

It seems eems odd your sender is only defective in a certain condition but not others...perhaps the highspeed is pumping a lot of oil up top and it just takes awhile to drip back into the sump.

Why not check the oil level when it's happening? and then again when it stops happening. This'll tell you if the oil level is a lot different...you can look at any passages too and consider if you've done a base gasket or something that might have somehow blocked a passage..especially if this symptom is new sine doing a job like that.

....the pickup screen in the sump? It's a pretty gross filter compared to the replaceable oil filter but sure- do that anyways-maybe change the oilfilter too.

but a differene of a hundred rpm? maybe your tachometer is overeading too. You might be at 800rpm-900rpm...
I take the sump plate off on every new-2-me bike..I usually don't find much but the stories in this forum! Somebody will find a finger in there someday...

[GregT]

Oil pressure relief valve probably sticking. Never had this happen to me but it's a possibility.
The valve is more likely to stick open after a high rpm run which is why I suggest it.
Dirty oil, spring in the valve lost tension...

It's accessible by dropping the sump. Spring specs are in the manual.

[grcamna2]

No, I haven't seen this.
Since your oil pressure light is ok otherwise, and they are pretty simple devices,( switch gets "pushed" by oil; the electrical path is opened...)oil pressure must be lower. It doesn't sound at all crucial if it goes away before you start doing a lot of idling at stoplights and so on...does it?

but maybe try a different oil....if it only does it NOW, summer, the highway, ...maybe goto 20w50..

I'm running Rotella T4 15/40 year round.
When the engine is a bit cooler(around town)the light doesn't come on at 1100rpm idle.

[grcamna2]

Oil pressure relief valve probably sticking. Never had this happen to me but it's a possibility.
The valve is more likely to stick open after a high rpm run which is why I suggest it.
Dirty oil, spring in the valve lost tension...

It's accessible by dropping the sump. Spring specs are in the manual.

I plan on opening up the sump at some point.
That pressure relief valve,can I remove it and clean it out,possibly stretch the spring out a little?

[GregT]

I plan on opening up the sump at some point.
That pressure relief valve,can I remove it and clean it out,possibly stretch the spring out a little?

Yes, it's accessible once the sump is off. I'd be more inclined to polish the valve bore and the little piston.
If the spring is out of spec, I wouldn't stretch it. Don't know if they're available new. Worth checking.
Very possibly the same part as a late GS500.

[John Park]

Suggested sustained cruising speed is usually about 2/3 - 3/4 of top speed, especially on air cooled bikes in hot weather. Keeping the pan clean helps, and also the air passages between the cylinders and the cam tunnel.

When the pan is off, inspect the gasket where the two holes come down from the filter cavity. This is under 45 - 70 psi [@ 3000 rpm and oil @ 60C or 130F] and any leakage will drain pressure right back into the sump. The blind holes in the pan are where particulate crap filtered out goes to die. The far end of the gallery is capped by the left cover and any gasket troubles there usually result in external as well as internal leaks.

I seem to recall the 650 fours having a low blood pressure problem that was resolved with a different spring. As Greg says, a GS500 spring might be in order given the probable price. But generally, aluminum blocks expand away from the steel cranks and cams and clearances increase with heat, which can lead to low rpm pressure loss. As long as there is flow, I don't care about pressure until the rpm is 3k or so. If you're curious, there is a plug on the rh end of the gallery that you can pull and insert a pressure gauge.

A stronger spring won't increase the hot oil pressure at idle. The relief valve is there to dump the excess flow and even a weak spring will close the valve long before the light comes on. Unless it's sticking...which is usually caused by rust on the plunger in cars, but I've yet to see it on bikes.

A full synthetic, while not so relevant on the roller motors, is probably going to hold its viscosity better at high temps. Given that these motors eat the occasional rod - usually the left - I'd give it some consideration.

[grcamna2]

Suggested sustained cruising speed is usually about 2/3 - 3/4 of top speed, especially on air cooled bikes in hot weather. Keeping the pan clean helps, and also the air passages between the cylinders and the cam tunnel.

When the pan is off, inspect the gasket where the two holes come down from the filter cavity. This is under 45 - 70 psi [@ 3000 rpm and oil @ 60C or 130F] and any leakage will drain pressure right back into the sump. The blind holes in the pan are where particulate crap filtered out goes to die. The far end of the gallery is capped by the left cover and any gasket troubles there usually result in external as well as internal leaks.

I seem to recall the 650 fours having a low blood pressure problem that was resolved with a different spring. As Greg says, a GS500 spring might be in order given the probable price. But generally, aluminum blocks expand away from the steel cranks and cams and clearances increase with heat, which can lead to low rpm pressure loss. As long as there is flow, I don't care about pressure until the rpm is 3k or so. If you're curious, there is a plug on the rh end of the gallery that you can pull and insert a pressure gauge.

A stronger spring won't increase the hot oil pressure at idle. The relief valve is there to dump the excess flow and even a weak spring will close the valve long before the light comes on. Unless it's sticking...which is usually caused by rust on the plunger in cars, but I've yet to see it on bikes.

A full synthetic, while not so relevant on the roller motors, is probably going to hold its viscosity better at high temps. Given that these motors eat the occasional rod - usually the left - I'd give it some consideration.

The engine only does it when it gets good and hot,lately since I've tuned it up it rarely has the warning light come on. I'm still going to pull the sump cover and clean it all up. Thank you for your post !

[GregT]

John - rust in relief valves was an occasional problem in Grey imports ex Japan in the 80's and 90's here. They'd sat in the open - often for years - in Japan before someone saw an opportunity to unload them. The relief valves are usually a low point in the system so water accumulates in them.
The typical Suzuki valve is a piston and spring - occasionally you'd see surface rust on the piston. The worst were Kawasakis, they mainly use a ball and spring.
One 750 I had through the shop was very bad - the oil light occasionally wouldn't go out at all. When stripped, the ball had a chunk rusted out of it. Pressure depended on the ball having it's good side down on the seat.

[Buffalo Bill]

Interesting blaming the pressure relief valve components.
Could it be the main crank bearings are worn?