My name is Kirk and I live in Nicaragua. I recently bought a k100 off a friend that flew back to she states to have a tumor checked in his throat. It ended up being cancer in hes larynx (voice box), kidneys, brain and lymph nodes. He made it 2 weeks. 
Fast forward a week and I got the new injectors brought to me by a visiting friend. Replaced the injectors, that the previous owner said was all the bike needed. The bike turns over and fires if I hold the throttle full open but only revs at 1000 rpm, FULL OPEN. I've drained the battery twice trying to start the bike. The third time I tried starting her, I had some electrical issues. 

1. The starter stuck on start after releasing the starter button.

2. The starter stayed stuck after I turned the power switch both left and right to the off positions.

3. The starter stayed stuck after turning off the ignition with the key, but the headlight illuminated while trying to start without the key turned on.


I also have a fuel leak somewhere because there is fuel leaking from under the back of the motor from the 4 exhaust pipes. 


I can't find parts here, I have no BMW certified mechanic (just the Clymer  and owners manuals) I need some guidance.

The only one in the country that has worked on this bike or PROBABLY any other k100 just passed away.

Hi Kirk welKome to the forum
If you go to the portal page then to the tech page you will find a flow chart that will help you.

Hi Kirk and welcome.

Multiple attempts to start will drag the volts down on the battery. It's a quirk of bricks that attempting to start with low voltage will cause the starter relay to get stuck in the on position.  Give this relay a pretty good tap and it will probably fix it, then there should be no continuity between pins 30 and 87. Then give the battery a good charge. 

It's a safe bet your friend was forum member skidz449, from the same city as you, Esteli. If you search this name I think you will find a bit about the history of your bike. He also found help from a nearby mechanic.

It seems to be flooding, can you describe which injectors you installed? Flooding is often caused by a faulty temperature sensor. 

skidz believed he had the only brick in Nicaragua, a 1985 K100. In April 2020 he posted his last thread that he had a flooding problem.

In yopuir first post 1 2 and 3 are starter relay. Worst case is to replace the starter relay, it is in the box under the petrol tank [the fuses are on the side of the box] and its held in place with 2 10mm bolts.

4 is a flooding issue, you need to be more methodical about this one as there are a number of potential causes.

If you can get a photo or VIN up it will help as there is are changes in K bikes in 85 that affect the fuel and vacuum system. Is your petrol tank held in place with a single 10mm bolt at the back, under the front of the seat?

92KK 84WW Olaf wrote:In yopuir first post 1 2 and 3 are starter relay. Worst case is to replace the starter relay, it is in the box under the petrol tank [the fuses are on the side of the box] and its held in place with 2 10mm bolts.

4 is a flooding issue, you need to be more methodical about this one as there are a number of potential causes.

If you can get a photo or VIN up it will help as there is are changes in K bikes in 85 that affect the fuel and vacuum system. Is your petrol tank held in place with a single 10mm bolt at the back, under the front of the seat? The gas tank

The fuel tank does screwed out of 110 mm bolt at the back.

daveyson wrote:Hi Kirk and welcome.

Multiple attempts to start will drag the volts down on the battery. It's a quirk of bricks that attempting to start with low voltage will cause the starter relay to get stuck in the on position.  Give this relay a pretty good tap and it will probably fix it, then there should be no continuity between pins 30 and 87. Then give the battery a good charge. 

It's a safe bet your friend was forum member skidz449, from the same city as you, Esteli. If you search this name I think you will find a bit about the history of your bike. He also found help from a nearby mechanic.

It seems to be flooding, can you describe which injectors you installed? Flooding is often caused by a faulty temperature sensor. 

skidz believed he had the only brick in Nicaragua, a 1985 K100. In April 2020 he posted his last thread that he had a flooding problem.

Daveyson, first off, let me thank you for this valuable information. I'm very excited to know that he was a member here. This week hopefully make things a bit easier. 
Second, I will check the today's under the tank, but I have to do something with the new battery, as it will not accept a charge. I'm not sure if I fried something by having the motorcycle try starting until the battery completely died, or if it just overheated so much last night that it wouldn't accept a charge. When I put the charger on on trickle it would be in charging and then half a second later it would power the charger off the red light would go out and the charger would click. There's a battery guy right around the corner from my house here and I will check with him this afternoon.
Third, I bought the injectors from Motor West Performance[size=34]Bosch Replacement Fuel Injectors for part # 0280150705 / 13641461523 84-03 BMW K100 / K1200 / K100RS / K100RT [/size]

Trickle charging doesn't work on batteries that have suffered a deep discharge.

If whacking the starter relay does not work to unstick it then I haven't done it personally but I've heard of people taking the starter relay apart to unstick it and clean up the contacts.

Once the starter relay sticks the only thing that will keep the starter motor from turning is disconnecting the battery.  The battery ground cable connects to the transmission down by the shift lever and is a quick way to disconnect your battery.

Before you try to start the bike again make sure that bolt isn't seized and that you have a tool handy to quickly disconnect the battery ground.

Some of us have replaced the bolt for the battery ground with an M6 knob so that the ground can be quickly disconnected without tools.

That will be a big help also, thank you

Davey, how do I search skidz449? I've tried and gotten no results

Olaf. There is a 10mm not holding the tank, so I believe it to be early 85

Bolt

It looks like your friend only posted 10 times here.  Here is the link to his posts.

https://www.k100-forum.com/spa/u5253 

At the top of each post is the thread it was posted in.  If you click on the title of the thread the thread will open up for you.

I just checked and clicking on the link doesn't work.  Try Copying the link and Pasting it in a new Tab.

It seems that the moto was running poorly when skidz449's last post concerning it was made in 2020.

Open the fuel tank cap before you try starting it, kappy. See if that helps get it going. According to the BMW parts fiche I consult, the old-style caps could create a vapor lock.

Go to Memberlist in the tabs at the top of the page and type in skidz449 to the "username" then click on OK and you will have the posts

I've decided that there are multiple challenges with this bike. 

I'm ordering a temp sending unit from the US, but need part number for early 85. Have a friend coming in 2 weeks.
I'm having a flooding problem, and I think it comes from a leak somewhere in the fuel tank. Every three days there is no gas in the tank, so it's leaking from somewhere. Going to remove the tank and replace hoses and clamps. 
I removed the plugs, they were wet and black.
I checked the air cleaner when I was checking the connections for the temp sending unit. It is quite dirty, will hit it with the shop vac and cross my fingers. 
Unfortunately, customs confiscates any car parts that are brought into the country, so they have to be small enough to fit in friends pockets when they visit. I'd love to replace the radiator hoses, but the new ones won't fit in pockets. That must wait. I have no electrical testing equipment here. But I do have mechanic friends.

kappy1027 wrote:I'm ordering a temp sending unit from the US, but need part number for early 85.

 61311459197 All the two valve Bricks have the same sensor, including your early 1985 model.

Thanks Laitch, my bike looks just like yours

Radiator hoses on Ks are pretty good and seldom fail though it wouldn't hurt to treat them with 303 protectant or a rubber revitalizer.

How do I post a photo?

Since you don't have electrical test equipment, I will guess your guessing that you need a new sensor, I'm guessing it might be ok.

You have a big fuel leaking problem and flooding problem, they might be the one problem, which you can check without specialized equipment.

For external leaks look under the tank, on the engine, hoses, and the tank vent drain behind the right foot peg plate(or follow the tank outlets) There might be internal leaks which would cause the oil level to rise, like leaking injectors or the fuel pressure regulator leaking through the vacuum hose to the rear cylinder at the throttle body. Remove this hose, if there are  signs of fuel or dampness, the regulator is leaking. If the regulator is leaking, it's important to not crank the engine until the fuel is removed from the cylinder.

When you say the tank leaks until it is empty, it sounds like there should be some large puddles of fuel forming under the bike where it is parked.  Because of the way the internals are configured, a tank that leaks to empty is due to only a couple causes.

First, and pretty common in bikes that have been idle for a long time is corrosion in the low spots of the tank where water can collect.  By running your fingers along the lower edge of the tank you can feel the bubbling paint and the leaking fuel caused by the corrosion.  Leaks in that area can be repaired by having the hole welded. 

The other spot where fuel can leak is where the electrical connections go into the tank.  Depending on the vintage of your bike the seal is made with a large o-ring or a gasket.  Because of the location of the fittings you need to remove the tank to see them.  Replacing the seal should correct the leakage.

If the leak is around the wires then it may be necessary to replace the fuel sender assembly.  Fortunately, that is not a very common failure.

Point-Seven-five wrote:First, and pretty common in bikes that have been idle for a long time is corrosion in the low spots of the tank where water can collect.  By running your fingers along the lower edge of the tank you can feel the bubbling paint and the leaking fuel caused by the corrosion.  Leaks in that area can be repaired by having the hole welded. 

This tends to happen more often on the left side when bikes are left on the side stand for extended periods. Run your fingers along the inside of the low point on each side of the tank. If paint chips come off then you probably have a leaky tank.

I do have puddles under the bike, it's a slow leak 1liter over 3 to 4 days. I've pulled the air box out and there was fuel under it on the block. I have 2 houses that are cut out broken tucked into the wires under the tank that I believe used to go to the 2 vent nipples on the bottom of the tank. Will fuel leak from these? I'm going to replace both fuel lines coming from the tank, but they will be from straight hose, I don't have access to the curved hoses that are stock. I'm also checking into the gasket around the pump, as I hear that kinda melts with age and leaks.

Davey, do you have a fuel pressure regulator part number really available? That may be at least part of the problem. I don't see a way to test it, so if it's not super expensive, might as well replace that too.

kappy1027 wrote:Davey, do you have a fuel pressure regulator part number really available? That may be at least part of the problem. I don't see a way to test it, so if it's not super expensive, might as well replace that too.

Bosch 0280160200
BMW 13531460451

Gracias Davey

Now that we know you have an external leak, my guess about the regulator leaking is probably wrong, that would normally cause an internal leak. In that case as the fuel level goes down, the oil level would rise. Another test to see if the regulator is leaking, is to remove the vacuum hose from the rear throttle body, if there is fuel in the vacuum hose, the regulator is leaking.

It seems that the fuel is puddling on the block rather than the head, that should help guide you. Now that you have the air box removed, its easier to see the regulator and return hoses. Check that the hoses aren't leaking. The regulator should have three hoses connected to it. If the vacuum hose isn't connected, the leak might be coming from the regulator spigot for that hose.

How to post a photo varies a bit, depending on your phone or computer. At the top of your reply;
Press the icon "host an image"
Press "select files"
Press up arrow icon "send image to selected category"
Pres the icon "insert image in the editor"
Then press the send button to post your reply.

Thank you Duck

Am I missing something? Like the security box! Or is there an electrical connector that should be connected that's hiding somewhere in this box?

White connector is for optional alarm system. Normal for it to be hanging out unmarried.

The black one is for the radio of RT and LT models.

The hoses should connect to spigots on the tank, the leak might be coming from one of those spigots.

Thanks again Duck and Davey

kappy1027 wrote:I do have puddles under the bike, it's a slow leak 1liter over 3 to 4 days. I've pulled the air box out and there was fuel under it on the block. I have 2 houses that are cut out broken tucked into the wires under the tank that I believe used to go to the 2 vent nipples on the bottom of the tank. Will fuel leak from these? I'm going to replace both fuel lines coming from the tank, but they will be from straight hose, I don't have access to the curved hoses that are stock. I'm also checking into the gasket around the pump, as I hear that kinda melts with age and leaks.

For those hoses, Honda use the same 8/13mm hose so you should be able to get them at a Honda dealership. I use straight ones and just cut them to fit. 

From my own experience with K bikes I would say there is a slightly higher probability the fuel is coming from a bad hose or even a leak from the tank iself.

I've checked the metal of the tank and there doesn't seem to be any corrosion or leaking from the edges of the tank itself. 

I'm hoping that the leak was from the dis connected hoses from the vent lines. I'm checking the vacuum lines shortly. 

Holding off on ordering any parts right now til I know what I'm looking at. Want to replace the lines first and see if she holds fuel.
Not real sure how a slow leak can cause flooding in an injection system though.

Thanks Olaf for your help. Keep it coming please.

This is my vin if anyone can verify it is an 85
WB1051305F8840172

It's almost starting. Loud backfire and then a growl. It almost started a couple of times this afternoon. 

I replaced both fuel lines and both vacuum lines and the two vent lines coming from the bottom of the tank. Filled her up with a bit of gasoline and..... No leak. 

It still isn't starting. Going to pull the plugs and see if they are wet. 
Then I will finish pulling out my hair.

The correct fuel injectors for 2 valve K bikes are Bosch 280150210, not 280150705. The 705 injectors have a flow rate that is about 12% higher than the 210s. 705s are used in the 4V K100RS.

http://users.erols.com/srweiss/tableifc.htm

If you still have the old fuel injectors check out the number on the side of them - it's 210.

kappy1027 wrote:I've checked the metal of the tank and there doesn't seem to be any corrosion or leaking from the edges of the tank itself. 

I'm hoping that the leak was from the dis connected hoses from the vent lines. I'm checking the vacuum lines shortly. 

Holding off on ordering any parts right now til I know what I'm looking at. Want to replace the lines first and see if she holds fuel.
Not real sure how a slow leak can cause flooding in an injection system though.

Thanks Olaf for your help. Keep it coming please.

This is my vin if anyone can verify it is an 85
WB1051305F8840172

Should that read 0040172?

duck wrote:The correct fuel injectors for 2 valve K bikes are Bosch 280150210, not 280150705. The 705 injectors have a flow rate that is about 12% higher than the 210s. 705s are used in the 4V K100RS.

http://users.erols.com/srweiss/tableifc.htm

If you still have the old fuel injectors check out the number on the side of them - it's 210.

I did have 705s in for a time [3,000 miles], they perform fine but fuel consumption increases.

I'd expect the bike to run on them.

92KK 84WW Olaf wrote:

Should that read 0040172?

Yep. 0040172 is a US K100RS built in 7/84 which would be the 172nd US K100RS - model year 1985.

Well, I put the old injectors back in. Two of the new injectors were running after I stopped pushing the start button. Are the injectors supposed to run for almost 2 seconds? The manual I have says 1.5 to 9 milliseconds. I'll try and post a video of mine during my test.

I know I'm probably bugging you guys by now but I just had the best bike mechanic in my town over it's the guy that Dennis was working with and he said that the air intake on cylinders 1 and 3 are bad. Would that cause the injectors to flow longer than they should or are they flowing longer than they should is two seconds too long on startup The pump runs for 2 seconds so I would assume the injectors would run for 2 seconds but maybe I'm wrong.
I've added a couple of pictures of the two bad intakes. We're going to push the bike over to the shop about 3 km away tomorrow at 9:00 a.m. my time. I'm hoping that he's on the right track. 
I don't have much more hair to pull out.

Seeing the build date of 07/84 made me realise the bike also might have a vacuum sensor, located beside the fuel pressure regulator. My 83 RS and my 84RT have this. There is an additional vacuum pipe take off from No 1 that goes around the front of the no 1 throttle body and connects to the vacuum sensor. 

Conventional thinking is that this makes no difference, but the vacuum hose may be cracked upsetting no 1 cylinder. Quick fix is to use a vacuum cap same as the others.

A quick test on the fuel pressure regulator is to pull off the vacuum hose to it from no 4 throttle body and replace it with a vacuum cap. If this makes no difference then the FPR is suspect.

Have you cleaned the injectors?  If they are still flowing after the engine stops cranking, it sounds to me like they are stuck open.  The two seconds of flow can be the fuel draining out if the rail.

Dirt and varnish will not only stop fuel from flowing through the injectors, but can make the pintle stick in the open position.

There are lots of YouTube videos explaining ways to clean your injectors.

Point-Seven-five wrote:Have you cleaned the injectors?  If they are still flowing after the engine stops cranking, it sounds to me like they are stuck open.  The two seconds of flow can be the fuel draining out if the rail.

Dirt and varnish will not only stop fuel from flowing through the injectors, but can make the pintle stick in the open position.

There are lots of YouTube videos explaining ways to clean your injectors.

I would agree with that, but I think a sensor of some sort is the culprit. The brand new injectors were also flowing for the same 2 seconds. I seeking help in figuring out which sensor would cause that, but the new injectors would be clean, I'd assume 

Would it be the fpr or the temp sending unit or the vacuum sensor that Olaf mentioned, that my bike does have. Could it be a bad Hall sensor? 
The plugs spark, the fuel pump is pushing 36psi, the injectors flow, albeit longer that my mechanic here feels they should.  All vacuum lines and fuel lines have been replaced. 

I don't know what else to look at. The bike mechanic here is going to look at the intake tomorrow, he says that the cracks in my photos allow air in which could cause the computer to call for more fuel. 
Did this sound accurate to more than just me

I don't think the computer is calling for more fuel, this is an early injection system, it's not closed loop, so can't measure an air leak.

Check that all injectors are ticking with a screwdriver between your ear and an injector.

I'm with point seven five, the injectors should pulse while the engine is cranking, regardless of the start button, but not longer.

If two injectors aren't ticking, you can use a computer safe 12volt LED test light to find if they're missing power or earth.

There's spark at the plugs, so the hall sensors are good.

Is fuel pulsing from all the injectors? I'm wondering if two aren't getting earth.

daveyson wrote:I don't think the computer is calling for more fuel, this is an early injection system, it's not closed loop, so can't measure an air leak.

Check that all injectors are ticking with a screwdriver between your ear and an injector.

I'm with point seven five, the injectors should pulse while the engine is cranking, regardless of the start button, but not longer.

If two injectors aren't ticking, you can use a computer safe 12volt LED test light to find if they're missing power or earth.

There's spark at the plugs, so the hall sensors are good.

Is fuel pulsing from all the injectors? I'm wondering if two aren't getting earth.

All 8 injectors are firing, only two of the new ones are bad. One goes during and after the others, another drips, so it's not closing completely. 
If the four old ones, they all fire as well, but for 2 seconds with just a touch of the button. They fire the entire time the fuel pump hums.

Maybe the computer is confused with the jab trick. I would turf the new ones, and check that the old ones all tick.

What is a jab trick? I don't want my computer confused, I'm confused enough!