Looking at the application, it appears to me that the tension load on these bolts is the clutch spring pressure and the result of the torque they are tightened to.  To me, the primary load appears to be shear resulting mainly from engine torque.  I will admit that I am not a mechanical engineer, so I am not familiar with the reasons for using a stretch bolt in a situation where shear is the main load on the fastener.  If I was designing the clutch, I would have specified a high strength fastener with a high shear strength and let it be reusable with Loctite.

P.S. Has anyone ever heard of a documented case where the clutch assembly has come apart due to the failure of these nearly $7ea($42 a set) fasteners?  Or is this another example of BMW's quirky and occasionally bizarre engineering and maintenance procedures? 

Hi all, short time lurker and first time poster. Thanks in advance for any responses

I recently acquired a 1990 K75 that I am trying to resolve an electrical issue with. The previous owner said the bike started to stall intermittently, but eventually would restart after a short time. Eventually the bike would crank but would not run. The PO replaced the fuel pump, but a new fuel pump didn't resolve his issue. This is the state I received the bike in.

I began troubleshooting by verifying the new fuel pump's operation. I supplied B+ and B- to the pump and it buzzed to life. The fuel pump fuse has voltage on both sides. I tested the tank fuel pump connecter and got the following results:

Key off test:
gr/wht wire- B+
yellow wire- B- (with some variance)
Brown- B-
White- B-

Key on test:
Gr/wht- B+
yellow- B- (with some variance)
Brown- B-
White- 1.0 volt

when cranking:
gr/wht: 0 volts (12 volts drops to 0)
Brown- B-

When back probing the green/white wire, while cranking, the pump buzzed to life. I was able to duplicate this by wiggling the probe. I then attempted to start the bike, and it purred to life. However, it would then slowly die, sort of like it was running out of fuel. I started it again and probed for voltage. As soon as the bike starts running the voltage drops to 0. As soon as it dies, the 12 volts return, and I can hear the pump buzzing. At this point I bypassed the connector and tested for 12 volts again while the bike ran. The voltage dropped to 0 when running and returned when it stalled.

So here are my questions:

Is the voltage drop on the green/white wire while running correct? or should I see 12 volts?

Am I correct in understanding the fuel pump should only receive voltage when the ECU sees a signal from the crank position sensor?

Am I going the wrong direction here?

I am looking for a top/tail box and it sounds like the 22l described in this thread would be good. The bike has the luggage rack pictured here. Are there boxes that clamp to or easily attach to these racks, or will any generic strap-on box do?

There's no push back from me, I'm agreeing with you, I don't think stretch bolts are needed, and I know the feeling you had when that last bolt broke. It's that bloke with a beard in the sky who sometimes stretches our patients to just before yield, to test us out.

I'm not familiar with K1100 bricks, but I'm thinking maybe they're just bolts. They could look identical to the original bolts, but do they look like torque to yield bolts? Maybe they're not, including the original's.

That should be unheard of, unless they're no-name bolts from who knows where. I have heard of no-name torque to yield bolts from who knows where that stretched beyond yield on first use (making them loose and two mm longer) But do they look like torque to yield bolts?