Topic: "RED" Oil Light Stays ON...

[TedH]

I picked up a '75 550 Super Sport on Tuesday (WHAT!!! I know, I know, what am I doing with TWO 550's but my rationale is that if others can own 4-5 motorcycles... why not me?!?).

Anyway, I started it and the oil light stayed on.  PO says he had not noticed it before.  Bike seems to run fine but I don't want to risk running with no oil pressure or a bigger issue (can there be one bigger than no oil pressure... I'm thinking not).

I dug through my 350-550 Clymers and there is surprisingly no mention of troubleshooting the oil light staying on.  I'm inclined to check the wiring diagram but not sure what to do with whatever I find.

My questions:  What leads the light to stay on?  The crankcase has the correct amt of oil (and it is fresh as is the filter).  Normally, the light is on and then goes off once the bike is started (from my experience).  I'm inclined to think there is a bad switch/sensor but what does it look like and where is it on the bike? 

Picture attached... 

[TedH]

I see in my search the oil pressure switch is located near the oil filter/cover.  If it can be tested... what is the procedure for testing using an ohm meter and/or a continuity light. 

Also, what are the proper settings/connections for testing via an ohm meter... I have an older unit that has the needle gauge and has to be 'zeroed' before each use. 

Many thanks!!!

[TedH]

I guess I better confirm where that oil pressure switch is... I'm seeing where other bikes have it under the trans cover... wish Clymers had the switch diagnostic 

[Bob Wessner]

I'm not that familiar with the 550, but in a generic 550 manual I have on a CD, looks as though the oil pressure switch is located on the left side of the engine. Looking at the alt. cover, the switch should be at approx. 2:00 o'clock. Do you have anything besides the Clymer manua?

[cb550fcafe]

Oil sending unit is under the sprocket cover. Oil warning system works on a single wire to the sending unit, when the wire is grounded the light illuminates. So the sending unit is a "normally closed" switch. As in; when the switch is "at rest"(no pressure) the switch is grounded therefore illuminating the light. Then when pressure enters the switch, it opens the contacts within the switch and breaking the path to ground which results in the light going out.

So, if your wire has rubbed through and grounded out, the light will stay on. This can happen under the sprocket cover.

If the sending unit is bad and never opens the conatcts, the light will stay on.

If you have no oil pressure, the light will stay on.

So first check for a chaffed wire contacting anything metalllic on engine under sprocket cover. After that, a mechanical oil pressure gauge is my next step. If you just want to try a new sending unit, I would only use a new one from Honda, as crappy ones and some o.e. ones tend to blow their tops off.

HTH.

[TedH]

I appreciate the good info.  One thing the PO mentioned was that he had rescued this bike from a 'Harley conversion' (some kid was stripping the bike to make it a chopper).  The wiring harness had been 'melted' (not sure what that really meant but he had to make some harness fixes).  I'll pull the sprocket cover and inspect the switch for resistance/connection.  Hopefully, it is just a bare wire grounding on the crankcase.  

Thanks for the info!  

[TedH]

I disconnected the switch and found the light went out.  Then, when I grounded the wire, it came on (with the ign key on).  I re-connected the wire and the light came on but after I started it, the light went out.  The switch connection looks a little corroded so I'm going to use an old tooth brush to remove the crud and re-connect.  That should take care of it.

Now, I just have to figure out why the front brake that PO said he rebuilt is dragging...

And, the header wrap (looks new), is smoking...

and, the carbs spew gas when the bike is off and the petcock is left open... I suspect the floats are set at the wrong height.  That IS something I can fix (been there, done that, have the t-shirt).

Thankfully, after taking it for a longer 2 mile ride, I found the bike accelerates and shifts very smoothly.  I took it for a shorter ride around PO's neighborhood (had very little fuel in the tank and was concerned the oil light was more serious than just a ground).

Just got to exorcise the brake/fuel demons then I'll take it for a longer ride. 

[Duanob]

Sounds like you got your work cut out for you. Nice to get the oil pressure light sorted out. If it were oil pressure problems you might 2X your actual pressure with a guage just to make sure.

[TedH]

I suspect air in the front brake lines.  After the bike sat and the rotor cooled it rolled easy.  I applied the front brake, released and tried to roll it and found it dragging.  Will advise once I bleed/fill with DOT3.

[Tintop]

I suspect air in the front brake lines.  After the bike sat and the rotor cooled it rolled easy.  I applied the front brake, released and tried to roll it and found it dragging.  Will advise once I bleed/fill with DOT3.

The sticking brake sounds like a dirty brake piston.  As the bike sits the piston is slowly retracting, but is just dirty enough that when you apply the brakes it isn't retacting properly, hence the dragging.  May only need cleaning up.

[TedH]

PO says he cleaned the caliper/piston.  I'm going to bleed the front system first.  If that does it, great.  Otherwise, I'll pull and clean the caliper.  He rebuilt the front master cylinder and installed new line(s) and crush washers.

[Tintop]

Agree with bleeding the brakes, if only to eliminate it as the problem.

....and the other great PO line - 'It was running when parked.'

[TedH]

I'm going to run a bottle of SeaFoam through the tank/carbs before I pull them to adjust.  It worked wonders on my 550K when I was sorting out its issues @ purchase.

[Tintop]

I'm going to run a bottle of SeaFoam through the tank/carbs before I pull them to adjust.  It worked wonders on my 550K when I was sorting out its issues @ purchase.

Sounds like your on top of it TedH.

[TedH]

Lotsa fun!!!   

[camelman]

Seafoam can do some amazing stuff.  I read a story on the XJ forum once about a guy who tuned and adjusted everything on his bike, got it running beautifully, and then ran a can of seafoam through it.  It ran really poorly afterwards because all of the build up that was in place when he did his prior adjustments came loose, so his tappet gaps opened up again.  I don't believe the story, but it sure was amusing. 

Regarding your oil light, I've seen that wire get pinched between the sprocket cover and the case.  That will cause a ground, and turn the oil light on.  If that happened, then you might see an occasional flicker of the oil light in the event that the wire is chaffed and touches the case.  Also, believe it or not, but I've seen bad oil pressure sensors.  I just replaced one on a CB500 recently because it was bad, although it only came on whenever the engine was good and hot.  I knew the engine was in good shape, so I swapped on a pressure sensor I knew was good, and it didn't come on when the engine was running anymore.

Check the plastic/nylon washer behind the driven brake pad.  If the pads are new, and the washer is out of place, then the brake will drag.  There isn't enough clearance with new pads for the washer to be out of place.

New header tape will smoke for a bit.  Don't worry too much about it... unless it smells like weed... then just slow down and enjoy the "roses".  ;-)

Camelman

[Deltarider]

but I've seen bad oil pressure sensors.

+1
I'd say every 500/550 needs to replace sensor at least once in it's lifetime.

[TedH]

I do wonder if the sender was sort of stuck ON.  I'll watch it and if it acts up again (knowing the connection is clean/secure) I'll purchase a Denso unit from Bike Bandit.

I'm sort of counting on the SeaFoam to clean the carbs somewhat.  PO had cleaned/rebuilt the carbs (exterior surfaces are so clean you could eat off them...).  I'm just adding 1-2 ounce to each tank.  Biggest improvement in performance has resulted from setting the points @ .014" and charging the battery.... I noted that the battery charge was weak when I picked it up but figured it had sat a while (it started stubbornly).  PO gave me a spare stator @ purchase.  If I have to hit the battery with 2amp trickle charge again then I'll check the charging circuit (or I may check it today... lots of spare time right now).

The front brake isn't dragging as much as it had been prior to bleeding.  I'm going to watch it and bleed it some more if it seems to drag/heat up.

Should sort the issues out soon.