Hi all, New on here and after your help. I recently bought a 1990 37,000 mile K100 which had been stood for a couple of years. The intention was to use it for my daily 60 mile commute. I used it for 3 days (having fitted a new tyre and battery) and it was brill. Ran nice, good weather protection and exceptional heated grips. Always fired up at the touch of the button and ran like a new motor. Has I went to come home from work on the fourth night it fired at the touch of the magic button but that was it. just kept cranking. It smelt strongly of petrol so I left it for 10 minutes. Now having done a bit of off roading in my time I thought 'flooded engine on a conventional bike' I then without the cold start held throttle wide open and Crank Crank Crank for 15 seconds it burst into life running sweet as you like and I rode it home. Since then it still doesn't start properly and that is the only way to get it to run. I have spoken to local bike dealers who have no idea or the equipment to test. Unless any of you guys have an answer it is going to have to be a 50 mile trip to a BMW dealer. Any ideas please? I have borrowed a Clymer manual but symptoms not in fault finder. Cheers Scoldy

A common problem is with bad earthing, check under the tank rider side of the electronic brain there is a earth point with quite a few wires, remove them clean using wire brush, emery etc. Another common which may be the easiest to check is behind left hand battery cover is a big multi pin plug, pop it off clean all the contacts and snap it back in, it must clip in properly.
Lastly check all electrical connection plugs, the pins do have a habit of corroding, we all use DeoxIT on all connections, can be found on E-bay.
That'l keep you busy for a while

Thanks Fella. Will give it a few hours attention at end of week. Will update. Fingers crossed

After sitting for extended time is a good idea to clean the fuel system and replace the filter. The rubber components ofter disintergrate and the bits get into the system you can get alge groths but it is more common in diesel fuel storage tanks but it does happen in petrol.

corrosion ...is the highest possibility besides mechanical breakdown


the under seat computer controls the mix via injector duration timing ...which in turn gets the signals from a few places

1> the temp sensor behind the radiator (relating to how hot or cold the engine actually is #Note the sensor actually starts off high value on cold and decreaces at it warms ) )

2> the air intake sensor ...(in the apeture of the afm (verry sensative to chemicals this one ))

3>the afm position electronics which usually relates more when above idle and some air passing besides the bypass through the throttle bodies and air bypass built into the afm for idle mixture purposes

4>the throtttle position sensor which has a micro switch in the closed position ....and as it aproaches full open another set of contacts the indicate to richen up the mix

5> the actuall under seat computer plug to controller

take your pic

if any of these sensors or switches has a high resistance (usually in the contacts of the actual sensor ,...or wire connection point )

things just get hard to deal with ....

mysuggestion ....get some "deoxit " and work your way around these locations and clean up all the little bits of corrosion that builds up there ...a tooth brush and some "contact cleaner " works well for getting the most part off ....but the deoxit treats the actual metalic connectors ....it doesnt last forever on things that have started happening ..but is your best friend to eliminate some of those issues

there is a efi troubleshooting topic in the "portal "section ....read and test the best you can

if you dont know how to operate a multi meter ...there is a great thread in the "how to" section by kbike ...a gem

it will help with all troubles efi related ....https://www.k100-forum.com/t725-using-a-test-meter-volts-amps-and-ohms

many have travelled this path ...and im pleased to say an overwelming "fixit" result has been noted by almost all

other things to concider could be

1> fuel presure regulator ....blocked possibly or just faulty

2> leaking injectors ...in this case maybe unlikely

good luck !!!

Hi Scoldy,



Dont give up on it because at 37,000 miles that engine will go on forever.

Getting the petrol tank off is a slow process and you will have it off more than once. BMW sold me the fuel pipe for about £15. Yours may well be perished but either way replace them with new pipe but longer so you can lift the tank up and away to access underneath without disconnecting all the fuel lines....Use thumb turn jubilee clips so you dont need a screwdriver to disconnect the pipes in the future. At the same time relocate the end of the earth towards the rear of the bike to facilitate this. The fuel pump connections under the tank should become a little more accessible. On the LT I now only have to remove the right hand fairing box to allow me to take the tank off.

If you do this it is so much easier to access the electrics and stuff under the tank.

Relays such as starter, load shed, can be got secondhand very readily from www.motorworks.co.uk or from motobins. Either are a great and reasonably priced source of parts. Most of the members have some of these lying around.

If the bike has been sitting the no 1 suspect seems to be the fuel tank pump and filter and seals so do this job anyway. Lot of posts here on that. Apparently the fuel pump inside the tank is same as Peugeot 205 gti and a few more....Seals break down in the tank from the ethanol in the petrol, also change fuel filter.

Electrical contacts under the tank are also suspect. Its a time issue, going through each one but do it one at a time so you dont end up with a maze of wires. A nice sunny day outside, tank off, cups of tea, its not a bad way to learn about the K.

I am no expert on the electrical system but its so modular you can go to one component at a time and check it out. However, there are a lot of warnings about disconnecting the battery before going at things, and also warnings about using self powered testers. Heed them, ignoring them can lead to expensive parts being wrecked. Most of the components will be ok but the contacts will be suspect after 20 years upwards in the open.

There is great technical information here but in my opinion there is nothing like having the Clymer manual to explore and see whats what. I would have been lost without it.

The K will bring you some great meets too!!!!!

Tried all I can and now booked in to Riders

Chin up Scoldy
we're all behind you mate.
You will get to love this thing soon enough.
RT

Hi Scoldy,
Good to have you with us, post your questions in the Technical section, not all of the gurus read the new members section so you might miss the vital nugget of info that will fix the problem. That said there is an excellent troubleshooting diagram on this site which logically takes you through a ladder diagram till the answer drops out.
Regards,
K-BIKE

Welcome to the forum

Now at a very nice independent BMW specialists in Cardiff. Got it going. Rode it the 40 miles and yes, it started at a touch when I demonstrated the problem. Suspect is mixture settings.

Scoldy



Many times I drove the M5 up through Monmouth travelling up to Birmingham.

You have some fabulous sweeping roads down your way, enjoy them. You got a good bike and you did well to find someone to sort the K for you.

My experience was that you get a few problems initially as the bike comes back into commission but they will be simple enough. Make sure you do things like change brake fluid, coolant, etc as well. You are unlikely enough to have to go near the engine, they go on forever.

Make sure never to overfill the sump, the red dot on centre of the sightglass glass on mainstand is your level.

Keep in touch here too, we Irish Eccentrics kind of love Wales and I am sure we will be checking out your roads at some point. I recall some gread roads up around Criccieth, Merthyr, Aberfan, Pontypridd and Brecon....

What is so interesting is that if you took all of the things that stop a K going, list is extremenly short. Makes it very easy to practice aircraft maintenance and just go through each one before it becomes a problem. If you do that over the summer or in winter you get a very reliable bike.

92KK

Rode them for years as Patrol bikes and bought it for commuting. Know the Welsh roads well as used to run my Advanced courses all around here. If anyone is down this way and wants a tour of our fine roads give me a shout. If I am off I will oblige. May be touring Ireland and Scotland in May June this year. Never been to Ireland.

Scoldy,

Keep in touch and let us know if you make it over. Dont feel tied to anything but we have a good spread of K bikes and always happy to meet someone for a coffee or whatever. I have been known to take a sunny day off work too...!!!!

92KK

Fixed for £50. Choke setting and injector cleaner. Motorad in Cardiff. Independent BMW specialist. Done a 1,000 miles on it since and spot on. Only K I have ridden with a smooth gearbox. Must have put a Jap one in it as oppossed to the Massey ferguson one. Lol

I am glad to see you sorted for relatively small money.

Now its time to enjoy the K. To be fair you got out of that one without paying over the odds. You dont get much for £50 these days.

A few meet ups over the summer....but you have nice roads so maybe persuade a few K owners to travel your way instead. Suss out a good place for coffee meet up and another one for lunch.........