Oil light on after oil change... also there's a difference in engine sound 81 GS750

[Guest]

Hello guys.

I just finished changing out the oil & filter and while running the bike the oil light was on constant and I noticed a slightly different sound in the engine.

Here's a couple notes:
1 - I used the same oil the previous owner used - http://bit.ly/1E1DKGJ but used a new K&N filter (KN-133)
2 - The pressure switch wire was pretty eaten up and kinked, but I was SUPER careful with it
3 - One of the cover bolts was missing and replaced with a nut and washer (looked pretty suspect and was only finger tight)
4 - no leaks before and no leaks after (I let it run for about 2-3 minutes).
5 - the old oil looked really good for the age and mileage on it.
6 - cold filled to the "F" on the filler window and while running, the filler window went to slightly below the "L";
7 - I drained 4 quarts so I put 4 quarts in.

My first thoughts were the switch due to the wire, but if the switch and the wire were bad, wouldn't the light just be off when the bike starts?!
Then I thought maybe there was a pressure issue due to a leak, I double checked all the bolts and everything is tight and again, there are no leaks.

I'm a little stumped here. You guys have any suggestions?

[tom203]

First get the right oil- that valvoline stuff is for water cooled cars. Shell Rotella T. 15-40 probably $14 per gallon at lots of places.

[JTGS850GL]

I'd start by verifying proper oil pressure light operation. Take the wire off the sender and ground the wire to the engine case. If the light comes on with it grounded but goes out when removed then you know that everything is good from there. If you have an ohm meter verify the resistance between the connection at the sender with the wire removed and the engine case. Start the engine and verify it again with it running. Don't run it long if the resistance doesn't go up dramatically once the engine starts. The fact that the oil level dropped once started is a good sign. It means that oil is being circulated to somewhere.

[disstance]

I can definitely do that. I was on the fence about the oil. He even included 5 quarts with the basket of goodies that came with the bike.

But why would putting the exact same oil that was in the bike, and had been used on the bike for the 10 years the PO had it affect the light today?

[JTGS850GL]

It shouldn't have. Just concentrating on the gauge since you mentioned the wire and you're using it as a diagnostic instrument.

As for oil amount, I believe you should need 3.4 quarts. The view window should show full after about a minute of stopping the engine.

[Rob S.]

But why would putting the exact same oil that was in the bike, and had been used on the bike for the 10 years the PO had it affect the light today?

It shouldn't have.

+1.........

[disstance]

ok fellas.

I think i got it hashed out.

I took the cap off to verify the switch was working properly, and it was. I noticed a couple of stray frays coming off the wire so I clipped those and pulled the cloth jacket over the wire, tightened everything back up.
Fired her up and it was working as intended. I guess some of those strays were grounding on the case or the cap and triggering the light.

I think I may have overfilled the case a little bit, the book said 4 quarts on the TSCC engines with a filter change it has 4 but the filler window is completely full.

[hampshirehog]

This is a design fault on this engine in my opinion and I've seen it on several 750s. The wire is exposed to everything that gets chucked up from the road and fraying of the wire is probably inevitable in the long run.

[disstance]

This is a design fault on this engine in my opinion and I've seen it on several 750s. The wire is exposed to everything that gets chucked up from the road and fraying of the wire is probably inevitable in the long run.

I would tend to agree here. I'm still a bit weary on the connection and the end that goes into the switch. It seems like any hard bump or a knock on the case could cause the strands to free up again. I was thinking about putting some electric tape over it or possibly zip tying the cloth part over the connector end... just for a little more peace of mind.

[guami007]

It shouldn't have. Just concentrating on the gauge since you mentioned the wire and you're using it as a diagnostic instrument.

As for oil amount, I believe you should need 3.4 quarts. The view window should show full after about a minute of stopping the engine.

I took a look at BikeCliff's site and manual for the GS750 and looked for this (see red text above) after getting things sorted with my carbs yesterday. Oil sight window did not show full after a minute of running the engine even after pouring 3.5 quarts of oil into crankcase. Heck, oil sight windown didn't even register any oil. After allowing mc to sit overnight, oil level showed at midway point between L and F this morning. Recent comments by eil here seem to indicate that oil level should be well above F after allowing mc to sit overnight but then eil also commented that "If the oil level is normally visible when the bike has been off overnight, you don't have enough oil in there". Unclear as to what 'normally' is referring to and therefore what is the best way to ensure correct level given there is already 3.5 quarts of oil in there. MC on center stand on level surface by the way. Apologies if I am not clearly articulating this.

Any feedback would be appreciated.

[tkent02]

No, that's not right. Before you start it the oil should just be visible in the window, then at least you know it has some. If the window is dry add a little until you can see it. Start it up, run it a little bit, then shut it off and wait one minute. At that point the oil should be to the upper part of the window. Anywhere in the window is OK but the upper part is probably better. If you have been riding just shut it off a minute and look at the window.

All of this with the bike sitting level or on the center stand.

When it's running you won't see any oil in the window at all, it's in there flying around the clutch and being pumped all through the engine and everywhere, the window will look empty.