85 BMW K100RT fuel leaks when I use the choke. I see the end of the arm opposite the cable pushes on something but am not sure what it is. Any suggestions?

I would suspect the handlebar switch for your lights as obviously power is getting through with the passing switch. Make sure the contacts are clean and no wire broken away.

I put one in a 1970 Chevelle. I bought the hand choke cable with pull lever and under dash mounting bracket. Mounted pull lever under the dash, drilled a hole in the firewall as high as I could, ran the cable out to the engine compartment. Mounted the holding bracket to the motor as close to carb as possible on the intake, then attached to the choke arm that works the butterfly plate in the carb throat. Cut to fit as tight as possible with butterfly plate closed and push lever all the way in. As you pull the hand lever out inside the car, it opens the butterfly plate to achieve the optimum air fuel mixture you desire to make the engine run smoothly. Sometimes you must go the opposite, lever out and plate closed, depending on the way the carb is set up, and work it the opposite way.

visit www.xjbikes.com theres a lot of info in there

without changing out your fuelline I would not reccomend to go for a higher pressure and flow.
About the fuelpump....sometimes going for the cheap option is in the longrun more expensive.

i have a 1985 k100rt and it would not start. i made some calls to bobs bmw in maryland and i unplugged electrical connector on gas tank ,sprayed it with electrical contact cleaner and coated it with dielectric gel. that fixed it. also check main grounding point on frame under gas tank.on a bike this old you need to make sure electrical connections are clean. the fuel pump is supposed to deliver fuel at 36 psi according to clymers repair manual. i hope this helped .

i have a 1985 k100rt and it would not start. i made some calls to bobs bmw in maryland and i unplugged electrical connector on gas tank ,sprayed it with electrical contact cleaner and coated it with dielectric gel. that fixed it. also check main grounding point on frame under gas tank.on a bike this old you need to make sure electrical connections are clean. the fuel pump is supposed to deliver fuel at 36 psi according to clymers repair manual. i hope this helped .