Hey folks im glad to have found this forum. i have a 1985 bmw K100. I live in Littlefield TX. and i havent found many folks with alot of knowledge about this bike. I've had a ton of issues with this bike. many of which im learning about in this forum. Currently my bike is in the shop for a couple problems.

1. its bucking. the tech says its the fuel pump

2. brake lights not coming on. simple switch im sure.

anyway glad to be here hope to be back on the road soon.

Welcome to the site.

Brake light as far as I can see on mine has a separate switch for front and rear, you seem to have both gone. Check the bulbs and the bulb holders, but also do check the earthing in the cowl over the brake light. Mine was dodgy and I ran a new earth to the frame under the seat.

Greetings Mike welcome to the forum. This is the place to get those problems worked out it's a gold mine of information, you may have to dig a bit but its all there.

Thanks guys! I am finding a wealth of info here. Seriously looking into getting it running. And possible transformation into a cafe style bike. I will try and post pictures of it soon.

Welcome Mike, you'll get it running all right and you'll be rewarded with a great machine. As Rick said you may have to dig a bit but the knowledge base here is a phenomenon! good look with it. Greeting from the emerald isle.

88KE

Mikehere as well.
Wish ya lived a little closer. Spring tx here...
For those looking at maps lts only 500 miles or about nine hours to get there!
If you havent gotten the deoxit stuff for your electrical connections, might do that. A little goes a long way..
This stuff can help tame those electrical gremlins that await underneath.
Fuel pump, change the filter while your there. Its an easy fix, yes i was able to do it.. With the help here and a manual to just make sure that i am not a total idjit...
Keep us in the loop how its going..
-o:

marenivaz wrote:Hey folks im glad to have found this forum. i have a 1985 bmw K100. I live in Littlefield TX. and i havent found many folks with alot of knowledge about this bike. I've had a ton of issues with this bike. many of which im learning about in this forum. Currently my bike is in the shop for a couple problems.

1. its bucking. the tech says its the fuel pump

2. brake lights not coming on. simple switch im sure.

anyway glad to be here hope to be back on the road soon.

FWIW, my experiences with K bike fuel pumps, they either work, or they don't. "Bucking" can be other things. Need more info. When does it buck etc. I'd be more inclined to look at the fuel filter, or perhaps fuel pump regulator. You can use a Ford Mustang 4.9 litre fuel filter with good results. Likely your NAPA store has one on the shelf, and it will be about 1/3 the cost of a BMW one.

I would test the fuel pump but I would not be too sure that is where the problem is.
Test the pump remove the filter end of the line from the top of the pump to the filter the with the line still inside the tank and your finger across the end of the line turn the key on and push the start button momentarily. Careful not to have fuel spray you but the flow and pressure should be such that you can barely stop the flow. If it is easily stopped then cactus pump. You will need to remove the fuel cap by the four screws that are visible when the cap is open.
If that is not the problem then start looking for an electrical intermittent open circuit and the best place to start is with the connector under the front left of the tank. make sure it is clean as water does collect in the plug and corosion will most likely be present in the plug and socket on the tank.
A product Deoxit is the best for cleaning electrical connections.

Uhm not sure how explain bucking. What it does is that it starts and idles well. When I get to 1800 - 2000rpms it acts like its shutting off but it isn't. It will do this throughout every gear. I had to drive it 40to miles to take it to the shop. That was a beating. Thank goodness for the friction cruise control. The tech thought it might be the throttle position sensor. He rode it and was convinced it was the fuel pump going bad. I'm not convinced but I didn't want to argue with only person within four hundred miles that "knew" anything about the bike. I was reading a different thread that described what I thought was the same problem I was having. If I read /understood the thread correctly I might need to look at the mass airflow meter. If I need to repost under a different area please say so I was just trying to introduce myself and hope to be around for a while.

im thinking similar ...re maf (metered air flow)...someone found theirs to be shorting internally ....well at least wires exposed to other devices ....also check the moovement of the flap, that its not sticking anywhere .

unless you have a horrible air leak from a colapsing tube or similar ?

Yeah I see what you mean now Mike I wasn't quite on the same track.
I would say that it is somewhere in the fuel air system. MAF sensor as Charlie has said or maybe the FPR (Fuel Pressure Regulator) could be doing it.
I didn't realize that it was such a repetitious thing I was thinking as often but not regular. We have come across a few MAF sensors that have been giving trouble recently.
Also check the small rubber tube that goes from the #4 throttle to the FPR, its enclosed in a long spring thing and could cause that sort of problem if it is colapsing under vacuum.

Good to have you with us. For troubleshooting start a new thread in the appropriate section of the forum because not all the experts read the into section so you potentially miss out on the good oil.
Regards,
K-BIKE