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R1150RT External Fuel Filter Modification

External Fuel Filter Modification for R1150RT

Bill Dennes  –


This procedure is based upon Rob Lentini’s “External Fuel Filter Modification R1100/850” and will quote a lot from that article. To keep you from having to read both articles at once, I have reproduced steps from Rob’s article here.

Like Rob, I have a story that makes me nervous about a fuel filter that I cannot reach while stranded by the side of the road. I was stranded just like that with my K-bike and was able to fix my way out of the problem by reaching into the fuel tank and changing the fuel filter there and then. It would have been a major disruption to my schedule and my mood if I had needed to wait for a BMW shop to open, get my bike in and fix it. If that had happened while I was riding my R1150RT before this modification, I would have been out of luck.

This procedure is for the R1150RT because the R1150RT has a set of quick-disconnect fittings in the supply and return lines from the tank. They are placed just above the right-side throttle body and are shown circled in the photo. Everything else but references to the quick-disconnects should work for the R1100RT – see the section “R1100RT Differences” at the end of this article.

The connection point for the new filter was chosen so the tank can be disconnected and removed from the R1150RT without disturbing the filter connections.


1.      Three feet of high pressure fuel line. Be sure to heed Rob’s advice and insist on high-pressure line. You can buy 5/16″ high-pressure line or get a one-meter hose with BMW part number 13 31 1 469 781 “Hose 8 X 13” and cut the three pieces you need from it.

2.      I used a Purolator F20011 fuel filter from Pep Boys. I used touch-up paint to mark a big flow-direction arrow on the filter.

3.      Four crimp-style clamps, BMW part number 16 12 1 176 918.

4.      Two screw-type clamps to attach the fuel filter, BMW part number 16 11 1 177 646.

5.      One new sealing O-ring for the fuel pump assembly, BMW part number 16 14 1 341 008.

6.      Two 7/8″ to 2-3/4″ hose clamps. I used a package of two Ideal clamps, part number 5036V, from Pep Boys.

7.      A pop rivet tool, with a short (1/4″) Aluminum rivet and two spacer washers. These will be used to join the two big hose clamps together to make a hanger for the filter.

8.      A dead inner tube or other source of two ¾” by 5″ rubber or cork strips.


You’ll need a set of special pliers to attach your new crimp-style clamps with. These are about $20 at an auto parts store. Take one of your clamps along to help explain what you want.


To do this job, both of the side covers must be removed. No work will go on under the left side cover, but the tank needs to come off.

1.      Drain the fuel tank by running it nearly dry or by siphoning it out.

2.      Break each fuel line at its quick disconnect (push the tab IN). Disconnect the wiring plug and the small-diameter tubes. Note that one set of the small diameter tubes is marked with these symbols ( >>>>>>>>>>) and the other set is plain.

3.      Once the tank is off, remove the fuel pump assembly from the inside right-hand surface (six Allen screws).

·        Unplug the wire that comes from inside the tank and tie a piece of string to it (and something big) to help you keep track of it.

·        The assembly did not come entirely free of my R1150RT due to two small lines that came from inside the tank and clamped onto fittings on the removed plate.

·        This meant that I had to re-use the existing gasket ring in step 6.

(Steps 4 and 5 are copied from Rob’s article:)

4.      “Observe the fuel filter mounted on the removed fuel pump assembly. Loosen the four crimped hose clamps and remove the filter and two short fuel hoses. One of the fuel hoses has a 180-degree bend, for reference.”

5.      “Replace the filter, two hoses and four crimped clamps with ONE 10″ length of new fuel injection hose and two new crimp-style clamps. Loop the new hose 180 degrees to bypass the entire fuel filter setup you just removed. Be sure to align the hose and clamps for neatness and non-interference with the fuel level float.”

6.      Use the string from Step 3 to pull the wire out of the tank and plug it back into its socket on the inside of the fuel pump plate.

7.      (also from Rob’s article) “Reinstall the fuel pump assembly (with new “O” ring) onto the tank. Be careful to NOT over torque the six allen-head screws, since the nut plates in the tank are known to sometimes strip out.”

(At this point, we return to mounting and connecting steps for the R1150RT.)

8.      Make a hanger to hold the filter:

·        Cut 2″ off one of the clamps. This clamp will hold the fuel filter. De-burr the cut end so it will engage smoothly with the clamp screw.

·        Drill a 1/8″ hole in each of the big hose clamps. Put the hole in the middle of the “solid” section of the clamp as shown in the photo.

·        Assemble the clamps and washers over the rivet as shown in the above two photos. Make sure that the tool end of the rivet sticks out of the larger clamp as the photos show.

It’s important that the rivet be Aluminum, not Steel, to allow the clamps a little room to rotate around the rivet. (The Aluminum rivet will “pop” before tightening as much as a Steel one would.)

·        Put the assembled rivet in your rivet tool and rivet everything together.

·        Cut a piece of inner tube or cork sheet ¾” wide and long enough to wrap nearly around the air induction tube that runs between the air box and the right hand throttle body.

·        Wrap the rubber strip around the induction tube and attach the larger hose clamp with the flat side (the head) of the rivet to the tube . The other clamp, which will hold the filter, hangs down from the induction tube. Place the large clamp so the tightening mechanism is behind the air induction tube (for side-cover clearance) as shown in the photo. Tighten this clamp gently so it can still rotate around the air induction tube.

9.      Mount the filter onto its hanger:

·        Cut a piece of inner tube or cork sheet  ¾” wide and long enough to wrap nearly around the filter.

·        Wrap the rubber strip around the filter and tighten the lower clamp over it as shown in photo 4. The arrow on the filter should point toward the front wheel. I placed the seam in the filter ahead of the clamp. Make sure the clamp screw is on the outside of the filter for ease of access during filter changes.

·        Adjust the position of the filter by rotating the larger clamp around the air induction tube to clear the side cover and tighten the large clamp gently. The filter and its clamp will pivot around the rivet to help in this adjustment. Final tightening of the large clamp will be done after all connections are made.

10. Loosen two crimp-style clamps on the motorcycle side of the supply (lower) line’s quick-disconnect and remove the two-inch section of rubber hose that was between them. Set the quick-disconnect fitting aside.

11. Attach one end of your unused fuel line to the solid line (going to the injector bodies, shown in photo 5) that you exposed in the previous step. This line is 11-1/2″ long on my R1150RT. Fasten the line with a crimp-style clamp.

12. Loop the line forward in a 180-degree bend to the front (outlet) side of the filter. Attach it to the outlet side (front) of the filter with a screw-type clamp.

·        (From Rob’s article: ) “NOW THIS IS IMPORTANT! Cut the hose to allow a smooth generous arc that contacts the cylinder finning and does NOT interfere with throttle operation. Start longer than you think and trim a little at a time to allow for a smooth arc and NO throttle mechanism interference on the right throttle body.”

·        (R1150RT version: ) Route the new line between the throttle cable and the fuel injector instead of behind the throttle cable. Route the line between the end of the stationary stamped metal bracket and the cylinder fins. This route keeps the new line clear of all the throttle mechanism’s moving parts. The line should not touch the throttle cable.

13. Replace the tank. Connect the wiring, the small tubes and the fuel return line at its quick-disconnect.

14. Attach one end of your unused fuel line to the supply line quick-disconnect fitting. This line is 14″ long on my R1150RT.  Fasten the line with a crimp-style clamp.

15. Spray a little silicone lube onto the male side of the quick disconnect and connect your new line to the line from the tank at the quick disconnect.

16. Loop your new line back outboard of the induction tube and just behind it in a 180-degree bend to the rear (inlet) side of the filter (see the second photo above). If necessary, cut the line to fit neatly. Attach the line to the filter with a screw-type clamp. Keep the position of the quick-disconnect release tab in mind before you clamp this hose to the filter: Rotate the hose so the tab faces out so you can use it easily in the future, then clamp the hose to the filter.

17. Rotate the larger clamp around the air induction tube to position the filter as close to the engine as possible (to make room for the side cover to go on). Tighten the large clamp snugly. Make sure that doing this does not cause the front hose to interfere with the throttle mechanism.

18.  Make sure that the right side throttle cable is positioned correctly at the throttle body end. The outer cable should be fully seated in the adjuster.


20. If you drained gas out of the tank, put it back. Make sure the bike will start. Check for leaks while the bike idles briefly.

21. Put the seat and mirrors on and test ride. Check for leaks again.

22. Put enough gas in the tank (a gallon) to turn the low-fuel light out and to display one or two bars on the fuel gauge. Make sure these things work. If they do, go ahead and fill the tank.

23. Put the right hand side cover on first, making sure the filter does not interfere.

24. Put the rest of the bike together (left side cover, black trim pieces, seats, mirrors again).

– You’re done! –


It all involves there being no quick-disconnects. You could:

·        Get two quick-disconnects from BMW (a 2002 R1150RT part, price unknown) or

·        Get them from Rider Wearhouse (800) 222-1994. They have 5/16″ q-d’s for $16 each. Remember that you’ll need two of them.

You’ll also need four more of the crimp-style clamps to install these.

If you buy q-d’s, connect them as shown in the first photo at the beginning of the article, and follow the R1150RT procedure above.

Disconnect the supply line from the tank where it meets the rigid tubing on the bike, and connect your filter loop in this junction.

Add one straight-through connector fitting that fits your flexible line and one more crimp-style clamp to the parts list, or buy six feet of 5/16″ high-pressure fuel line and replace the supply line beginning at the tank.

To place the lines to/from the filter, remove one  crimp-style clamp and disconnect the supply (lower) line from the tank where it connects to the rigid tubing on the bike. Use the connector fitting and two crimp-style clamps to extend the supply line into the new line going to the supply side of the filter. Run the line from the outlet side of the filter to the rigid tubing on the bike and use a crimp-style clamp for that connection.

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