Good Day Brickheads. 

I just picked up a '91 K100RS (16V)

... supposedly owned at some time by Richard Backus from Motorcycle Classics. The gentleman I puchased the K-RS from, Mr. Travis, from Lawrence Kansas, said he bought it from Mr. Backus back in 2014. The 2014 title shows 80K on the clock. When I bought the K-RS from Mr. Travis, yesterday, the odometer showed 91K on the clock but the he said the clock had stopped working just last year. Mr. Travis seemed to be very up and up about the bike...nice gent so I'm going to reckon the bike has around 92-93K at the most. This bike makes my third FLYING BRICK. Back in 2000, I owned a gorgeous '93 blue K75RS conversion (gone), then a '96 K1100RS (gone) and now a '93 K75S (love it) and bought yesterday....the '91 K100RS. I hadn't joined the group earlier because I've just been extemely busy with work and the K75S has been doing well. The K100RS is a different beast. 

About me? I'm a single retired US Navy Chief and I'm loving life down here in somewhat rural Arkansas. Up to now, I've owned about 30 bikes. Considering I bought my first bike in 1999, that may seem excessive, but we have to have our hobbies...right? My other hobby used to be Alfa Romeo cars, but I got out of that back in 2015. Kinda miss that. Yeah...really miss that, but too expensive because I like things to look and operate close to new.

 I now own a '77 R100/7, the '91 K-RS, '93 K75S, 2001 Honda Valkyrie and two 2004 R1150RTs. Zero HDs. Why do I mention HD's?...another story.

My newly acquired K100RS does have it's issues, but I knew that going in. Honestly, I just absolutely love the look of these bikes. Next to a Daytona Orange R90S, these are my next favs. 

The K100RS starts fine, idles fine, shifts fine, but sporadically stalls. Mr. Travis seemed to think it was related to the KILL switch, but I have my doubts. I'm gonna upload a video to YOUTUBE when I can to show the symptoms.

Anyway, I'm glad to be a new member of the group and I'm looking forward to sharing knowledge and experiences if I can.

Dao

Welcome Dao

A good K is a base for a happy life (unless you like wrenching)  

A good start is this page; https://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm
As this is a member introduction, all questions in the (if possible) right section

Welcome!  The 16 valve K100RS is my favorite brick.  I've had two of them now that I've dressed in K1100RS fairings. 

Does your bike stall when you throttle off after running at high speed( like when you stop at the end of an off ramp on the interstate after a long run)?  I had that problem with one of my bikes, and replacing the brushes and the voltage regulator made it go away.  I suspect that the voltage control when the regulator is hot allows the alternator output to drop too much when the engine speed drops.  It's just long enough that the Motronic stops injecting fuel to stall the engine.

Concerning stalling, I just bought the bike on Wednesday December 1st and haven't had the chance for a real ride. I purchased the bike knowing it had the issue. I rode it a couple blocks right before purchase and it stalled several times, but started up again immediately. The previous owner said it was more than likely the KILL switch and I definitely now agree. Here's a brief video showing the problem: YOUTUBE VIDEO SHOWING STALL ISSUE

I've already purchased a replacement combo switch and will replace it as soon as it comes in. I'll also go through the bike, replace fluids, switches, get new rubber, etc.  I'll post about what I'm doing in the appropriate areas, but wanted to answer your question.

Dao

Get a can of Deoxit D5.  They have it at music stores for cleaning the volume controls on guitars and amps, or some hi fi audio shops.  You will need it to go through and clean all the electrical connectors and switches to get the electrical system working reliably. 

The combo switch is held in place by a single Phillips head screw.  Once you get it off, you can get to the contacts in the kill switch to clean them.  That is the first thing I would do.  There is a good chance that the hardest part of this job will be getting the Deoxit.