1983 R100RS Rebuild: Oh S^%$t The Oil Light Came On!

Since I got this bike running a month ago, I’ve been taking short trips with it so I can have some confidence it is reliable. I was riding along at about 50-60 MPH on a 93 F day when all of a sudden, the red oil pressure warning light came on just as I turned on to the road to my house. I immediately hit the kill switch, pulled the clutch and pulled over to the side of the road. I waited for a minute and then started the bike again. The oil pressure light went out immediately. Hmm.  I started riding and about two minutes later, the warning light came on again.  So, I went through the same drill of immediately stopping the engine and waiting for a bit. On start up, the oil light went out immediately.  This time I made it home just as the light came back on.  Not a good sign.

So, I’ve been on a journey to isolate why the low oil pressure light comes on intermittently. I found several problems in the oil system of this bike and corrected them. You can read about what I did here:

I took apart the oil filter and inspected the paper, but the consensus of folks on the Micapeak Airhead forum was there wasn’t anything to worry about in the filter.  Big sigh of relief.

As I continued my investigation I diagnosed and fixed a couple problems in the engine oil system. But I’m not absolutely certain I have found the problem causing the low oil pressure light to come on. I’ve ruled out failures in the engine oil system and am convinced the oil pump is working properly, the engine oil passages are not blocked, the oil seals are not leaking, the oil pickup and screen are okay and the oil level is correct.

The electrical circuit is now the most likely reason for the intermittent low oil pressure light coming on. The last thing I replaced is the oil pressure sender switch even though when I originally tested it, it worked. But, it’s the next most likely component to have a problem due to its mechanical action. Here’s a short video of the insides of that switch.

Inside Oil Pressure Sender

I’m hoping the next hundred miles or so I don’t see that oil light on the dash anymore, but time will tell.

Here are a couple pictures from the detailed write-up.

Distance to Measure From Edge of Filter Can to Top of Engine Block

Distance to Measure From Edge of Filter Can to Top of Engine Block

Vernier Caliper Reading 3.82 mm Canister Depth

Vernier Caliper Reading 3.82 mm Canister Depth-Much More than 3 mm Specification

Cutting Filter Paper Cylinder From Metal End

Cutting Filter Paper Cylinder From Metal End

Bright Metal Particles

Bright Metal Particles

High Pressure By-pass Valve Parts-Mangled and Bent

High Pressure By-pass Valve Parts-Mangled and Bent

Fishing Ball Bearing Into Hole

Fishing Ball Bearing Into Hole

White ($2,000 O-ring) Installed in Filter Cover

White ($2,000 O-ring) Installed in Filter Cover

Attaching Oil Test Gauge to Instrument Cluster For Test Ride

Attaching Oil Test Gauge to Instrument Cluster For Test Ride

One thought on “1983 R100RS Rebuild: Oh S^%$t The Oil Light Came On!

  1. I JUST LOVE following Brook’s work here — precise , methodical, comprehensive and the photos are truly worth 1,000 words. TY

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