GS850 oil presure

[Brendan W]

Took the non functioning oil switch out to free it up and now every time I pull the clutch the oil lamp lights up ( no the cable is not fouling the switch connector) and at 2000 rpm overruning it lights up but as soon as the slightest bit of throttle is rolled on it's out again. This normal ? Just got the bike two days ago and can't stay off of it for more than an hour , no idea when last oil/filter was done.

1981 GS850G

[Triam]

Well, since no one has responded yet, I'll start:

So when you say you took out the switch to free it up do you mean that it was stuck and wasn't working?
The fact that a higher RPM lights up the light, but it isn't lit at lower RPMs makes me think that it's not a problem with your lubrication system, but with the switch. It should go off when the revs go higher.
It kinda sounds fishy that pulling the clutch would affect the pressure. There's a gear behind the clutch that engages the pump, but that should always be engaged and pulling the clutch lever shouldn't change that.

As for not knowing when the last oil change was, I would change the oil if I just got the bike. You don't want to take that bike too far on bad oil, and you certainly don't want to take it very far with a clogged filter. The bike will bypass the filter if there's not enough flow, and unfiltered oil gets real ugly real fast.

[Triam]

The spur gear in the picture connects to the oil pump. The splined shaft is what the clutch turns only when it's engaged.

[Brendan W]

The switch was stuck open I guess. Can't say I found anything , just pushed it a few times and now it works. I think this was low oil level even though the level was showing 3/4 full. It didn't happen straight after start , took a minute or so by which time a lot of oil has gone walkabout. Then my theory was that the plates of the free clutch act like slingers and drop the level fairly sharp but if I read the pic correct the oil pump drive is on the 'far side' of the clutch. Added about 100cc and it cured it completely although I suspect the filter is not helping. That window is not the easiest - gonna drop the bike on my head one day.
Oil and filter are top of the list today and thanks for the pic it was exactly what I was searching for.

[eil]

That window is not the easiest - gonna drop the bike on my head one day.

There should be no risk of that if you're following the procedure as described in the manual:

1. Put bike on centerstand
2. Idle the engine for a little bit (just enough to get the oil circulated)
3. Turn engine off
4. Wait exactly 60 seconds
5. Check oil level in sight glass

Step #4 is especially important. If you try to check the oil immediately after the engine has been running, it's going to appear to be low. If you wait too long, it's going to appear to be too high.

[Steve]

Just got the bike two days ago and can't stay off of it for more than an hour , no idea when last oil/filter was done.

You are riding it and you haven't done basic maintenance?

Not even to verify whether the previous owner actually did any of the things that he promised?

At the very least, you should change the oil (and filter), check valve adjustment and at least verify carb settings, possibly even clean the carbs (full strip-and-dip method) and replace the o-rings.

I just can't imagine taking a bike any farther than the end of my driveway before doing all of that, AND MORE.

.

[Triam]

Also, if the engine is hot, and it's a hot day sometimes the light will be on even when there's flow. If you rev the engine a bit the light should go off.

[Nessism]

The problem described, pulling in the clutch and the oil light illuminating, has nothing to do with actual oil pressure. You have an electrical problem. Both the side stand lamp and the oil lamp share some elements of the same circuit. Crack open your factory Suzuki service manual and/or the wiring diagram on basscliff's website, and start tracing some wires.

[Steve]

The problem described, pulling in the clutch and the oil light illuminating, has nothing to do with actual oil pressure. You have an electrical problem. Both the side stand lamp and the oil lamp share some elements of the same circuit.

I agree that it's an electrical problem, but the '81 850 does not have a side stand lamp.

That feature arrived with the '82 models.

.

[Brendan W]

Firstly thank you all again for taking the trouble to respond.
Oil changed with filter.Motul 10W40 semi and HF133. Small amount of fine paste on the sump plug, old filter fairly clean and looked new, no sign of sludge or grit in the filter housing.
The oil pressure lamp is still coming on but only after the motor is hot and only when the clutch is pulled in and only below 1500 rpm. It does not do it every time and does not stay lit. When it does happen it blinks slowly for a time.Partially releasing the clutch gets it to go out.
Am I right in thinking that with the bike on the stand the only drive to the oil pump with the clutch pulled in is the drag on the plates?
Suppose I need to figure out how much time I plan to spend below 1500rpm with the clutch pulled in
Final drive oil came out looking good as well. Fine layer on the drain plug and the corners of the fill/level have seen better days. Six point sockets only please.

[boingk]

Good stuff mate, I'm a stickler for maintenance as well and always try to get it done ASAP with a newly acquired bike.

Check your wiring as the fellows above have said, one thing you definitely want working is your low oil pressure light... otherwise if you *do* have a serious problem... your engine is toast!

- boingk

[Nessism]

Does the bike have an aftermarket oil cooler installed? If so, you are likely getting internal leakage around the pickup plumbing.

[Brendan W]

No cooler, no plumbing at the end of the gallery just a plain hex plug. Tried it with the wire to the pressure switch disconnected and it wont light the lamp so I don't think the loom has found a clutch activated route to ground for the pressure switch cct.

[Steve]

Am I right in thinking that with the bike on the stand the only drive to the oil pump with the clutch pulled in is the drag on the plates?
Suppose I need to figure out how much time I plan to spend below 1500rpm with the clutch pulled in

No, the oil pump is driven any time the engine is running.

I would hate to think of the consequences if it were driven by the 'dead' side of the clutch.

.

[Brendan W]

This bike has a sense of humour. Oil lamp lights up prestart and goes out in less than a second from starting to crank and stays off in all normal phases of riding. As said before when the motor gets hot pulling the clutch in will 50/50 make the light blink for a few seconds at less than 1500rpm however there is nothing I can do to get the oil pressure lamp on when the bike is running on the side stand. I can sit on it, upright or leaning right the lamp may come on but a few degrees to the left and no way will she light up. The big spannerman in the sky having a laugh at my expense. Selecting first before the motor is hot will also bring it on , provided you're not leaning to the left that is.
I see a pressure gauge and an oil pan gasket in my future.