Another newbie with a ‘91 K100 LT non runner

Battery charged, tank cleaned out with fresh pure gas, engine will fire on starting fluid.

Bike has 139,000 miles on it but has been sitting for more then 4 years. Owner claimed he had $1200 “tune up” by BMW Dealer just before he had stroke. Fuel pump is running.

I had a problem getting to plugs- the three 5mm cap screws would not break loose but I solved that. Tried to pull plugs, but they don’t seem to want to accept my 18mm long reach plug wrench. Came it to see if I could find what size it should be on line, and every thing I see sz 18mm 5/8 is way small. Only thing I can think of is that the foam in the plug wrench has lost its give.

After I check the plugs an throw a little oil in each hole to increase compression, I think I will need to get the left fairing out of the way and see if I can get to the fuel injectors. Any tips on seeing if there is fuel pressue befor the injectors? I would hate to order new injectors if I don’t have to. I’m getting into an area I have not been before. About anything with a carb I have done but I have never worked on FI.

Craig

You can "T" into the fuel line between the tank and the fuel rail with a conventional pressure gauge. That will confirm pressure. Or just disconnect that fuel line and look for a strong ruel flow into a suitable container. If you hear the pump running and it isn't squealing you can be pretty sure you have good fuel flow.

The injectors are notorious for clogging after sitting for a year or so.

PGlaves said:

You can "T" into the fuel line between the tank and the fuel rail with a conventional pressure gauge.

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Or "T" between the rear of the fuel rail and the hose that disappears behind the throttlebodies. This hose goes to the pressure regulator. On an RT, this hose is accessable, unlike the tank to fuel rail hose that is covered by the fairing.

You should have around 38 psi. If the needle on the guage is wildly fluctuating, pinch down on the hose between the T and the guage with a pair of pliers until the reading is more steady, but don't pinch it completely off.



Make sure the fuel filter is not plugged. The filter, along with the injectors, tend to plug up like Paul said, on bikes that have sat for a long time.

Craig,

Yes, the plugs are SUPPOSED to be 18mm (Bosch X5DC). Someone probably put the wrong plugs in it. Try 16mm (or 5/8"). Ya never know what ya get for a $1200 tuneup these days.

If you have the factory tool kit, there is an 18mm plug tool in there.

Well I solved the plug wrench problem. The bike has Champion spark plugs. They have 5/8” nut drive. Oddly, unlike the 5mm cap screws on the cover, the plugs are little more then finger tight. The fact that the 5mm cap screws were locked up (ended up having to use a hammer driver to break them loose) makes me wonder about that $1200 tune up claim. But no matter, I got them out.

You should replace the plugs with the correct plugs. Bosch X5DC. Do NOT use any resistor plugs on a K75, as there is a resistance gap built into the wires. Because of this gap you can not resistance test the plug wires.