Greetings from Georgia!

About 6 months ago I bought a low milage '87 K100RS to use in California. I've been working to get the old and worn parts renewed, and have managed to put about 5,000 miles on it so far.

My last BMW was a '83 R100RS - I guess I'm a little slow on the new models.

In Atlanta I have a Moto Guzzi and 3 Ducatis. But I've had so much fun with my K100, I may have to have one here too.

I'm presently sorting out a gremlin on my K100 - it quits when hot, restarts and runs fine after about an hour of cooling. I've had my mechanic in San Francisco replace some of the primary suspect components (hall sensor, FI relay, fuel pump) to no avail. Nice to have the new parts, but now needing serious diagnostic investigation.

I'd be delighted to meet fellow K100 riders in both Atlanta and San Francisco.

Cheers - Joe Stroup

G'day Joe , same thing used to happen to my 87RS , it would quit in traffic on the way to work each morning , ended up being the cable clamps on the battery being loose , bit of thermal expansion and it would quit , have a look see

Ciao & welcome

JR

Melbourne Australia

Hi Joe welcome to the forun. Good to see another happy brick owner.

To me your problem has all the marks of a dying Hall effect sensor which is what triggers the ignition.
Go to the portal from the main page and then to the K100 ignition trouble shootong section and let that lead you through testing.
If you need to replace the sensors Honneywell makes them and sells for one heck of a lot less than OEM.
Hope this helps.

Also clean out the starter motor and replace the brushes. This can cause the problem you're describing. The parts are cheap ($30 US), and once you pull the battery to check its cables - the starter is right there, secured by 2 screws.

JR_K100RS wrote:G'day Joe , same thing used to happen to my 87RS , it would quit in traffic on the way to work each morning , ended up being the cable clamps on the battery being loose , bit of thermal expansion and it would quit , have a look see

Ciao & welcome

JR

Melbourne Australia

Hello JR -

I'm learning that on this bike, it's all about the details. Thank you for your suggestions.

I had the battery replaced before my problem started - so the cable clamps might have been poorly connected. I had the ground cable replaced after the problem started - so I would hope that side is good - but will re-check both connections to be sure.

Of the 9 bikes I've owned in my life - this is the first "old" bike I've had. I'm learning about care and maintenance in a whole new way.

Thanks for helping me!

Joe Stroup

Rick G wrote:Hi Joe welcome to the forun. Good to see another happy brick owner.

To me your problem has all the marks of a dying Hall effect sensor which is what triggers the ignition.
Go to the portal from the main page and then to the K100 ignition trouble shootong section and let that lead you through testing.
If you need to replace the sensors Honneywell makes them and sells for one heck of a lot less than OEM.
Hope this helps.

Greetings Rick -

The Hall Sensor was indeed one of the components that was suggested early in my investigations - and before I learned about the Honneywell sensors, I had my mechanic install a new OEM part - very expensive indeed!

The problem still exists - so the search continues. It would be easier if I could duplicate the problem in the shop. And as I keep the bike in San Francisco, but live in 2000 miles away in Atlanta - I'm sadly dependent on my mechanic. (luckily, he's a great mechanic)

The K100 Ignition Troubleshooting Section is a great resource. I've learned a great deal from it. I'm going to ask my mechanic to see if letting the bike idle in his shop for an hour or so might be a way to get the bike hot enough to duplicate the problem. I'm sure the diagnostics will be much easier with the actual problem in play.

As much as I'd love to have a bunch of shiny new parts on this bike - it's simply not possible to replace everything. I've probably already spent twice the cost of the bike on restoration. It's a good thing I love riding it so much!

Thanks for your kind input - it's amazing to know my project has become a world-wide effort!

Regards - Joe Stroup

BadjerJim wrote:Also clean out the starter motor and replace the brushes. This can cause the problem you're describing. The parts are cheap ($30 US), and once you pull the battery to check its cables - the starter is right there, secured by 2 screws.

Hello Jim - nice to hear from a fellow so close to home!

I grew up in Sacramento - just down the road from Chico. Perhaps we can coordinate some riding when I'm out in California riding my RS.

Cleaning and renewing the starter sounds like good advice - under any circumstances, given the age of the bike.

I'm curious about the possible connection between the starter and my problem with the engine quitting. After it quits - the starter still turns over the engine - it just won't start again until the bike cools off. Can you help me understand how the starter might be causing the bike to stall?

I plan to do more riding in the north-eastern part of the state - I'd love to hear about your favorite riding loops from Chico.

Once again - thanks so much for your suggestion!

Best regards - Joe Stroup