Valve clearances are ok but have one on the intake that is slightly tight. (.01mm) so going to leave it but have a look in a 1000K or so.

So........ brusha brusha started looking at the plug black and wet with gas. Time to do some testing. Motronic so check the TPS always 2500ohms so thats a change out. looked up part on BMW web site for kicks a bargain at $322 CAD "loonie" you might think when the amazon price delivered is $46 (does it matter the denomination.

It arrives tomorrow. 

P.s. Cut open the old TPS not serviceable.

If your looking for testing of motronics its in the tech area. Thanks to that guy for putting it up.

You can ride without a TPS, I disconnected mine years ago to make it smoother to ride in slow traffic and carparks. It is supposed to eliminate the back firing on overrun. But I have found that if you have the mixture correct, no exhaust leaks and clean injectors with the correct spray pattern this works. You do have to close the throttle fully on overrun. The richening up of the mixture at full throttle is also part of the TPS's duties which I keep meaning to reinstate by reconnecting the plug and misadjusting the TPS to stop it cutting fuel supply off idle.
Regards Martin.

MartinW wrote:You can ride without a TPS, I disconnected mine years ago to make it smoother to ride in slow traffic and carparks. It is supposed to eliminate the back firing on overrun. But I have found that if you have the mixture correct, no exhaust leaks and clean injectors with the correct spray pattern this works. You do have to close the throttle fully on overrun. The richening up of the mixture at full throttle is also part of the TPS's duties which I keep meaning to reinstate by reconnecting the plug and misadjusting the TPS to stop it cutting fuel supply off idle.
Regards Martin.

Not if it's a 16 Valve engine.

This bike is new to me and I have only run it for about ten minutes. It's dead of winter where I am. I have a heated garage. Might as well fix what I can find.
The bike is a 90 K100rs 16v with almost 18k Kms. The lack of mileage could be hiding problems so as I'm exploring the bike I'm checking the 28 years of age averaging 650 km per year.

Besides the rubber mount for the fuel pump usually going bad in an idle engine the years are hard on the rubber bits(hoses and seals) and the electrical connections. 

Check every hose for cracks and splits, and clean the bike thoroughly so you can see any seepage of oil or coolant.  Go through the wiring from front to rear with a can of Deoxit contact cleaner and give every connector, switch, and bulb socket a light spritz and work it a few times to clean up the contacts. 

If you do those two jobs, you will eliminate a large percentage of the potential running problems that may arise when commissioning an old bike that has been idle for a while.