The original fuel lines used on GL1100 is 5.5mm - and virtually impossible to find. Fortunately, standard automotive 1/4" (6.35mm) fuel line will work - the extra 0.85mm can be taken up with clamps. I decided to use steel-braided fuel lines - which makes it a bit harder to cut, but adds an extra layer of protection, as well as a nice appearance.
IMPORTANT: It should be obvious, but working with the fuel system will expose you to fuel and fuel vapors, which are flammable/explosive. There should be no sources of ignition (cigarettes, pilot flames, sparks, etc) anywhere in your work area, and there should be good ventilation at all times.
1. First, we need to remove the fuel from the existing fuel line. Turn the fuel petcock to "ON".
2. Start the motorcycle normally, and establish a fast idle.
3. While the motorcycle is running, turn the fuel petcock to "OFF".
4. After 30 seconds or so, loosen the clamp fastening the fuel line to the petcock.
5. Pull the clamp down on the fuel line to free the hose barb on the petcock.
6. Gently twist and pull the fuel line off the petcock.
7. Hold the fuel line up so as to not spill any fuel that may be remaining in it, and to keep fuel in the filter. Hold the fuel line in this position until the engine stalls from fuel exhaustion. Turn the ignition key off. At this point, the fuel lines and filter should no longer have fuel in them.
8. Remove the crankcase vent clamp and hose from the crankcase, to facilitate access to the fuel filter.
9. Loosen and remove the clamps on the fuel pump lines, both the left (input) and right (output).
10. Gently twist and pull the fuel lines from the fuel pump.
11. Looking in from the right side of the motorcycle, you will see a nut holding the fuel filter assembly to the tab on the front of the fuel tank.
12. Using a socket extension, loosen and remove the fuel filter retention nut.
13. Push the fuel filter to the left side of the motorcycle to free the stud from the frame, then gently remove the fuel filter assembly to the right.
14. Remove the screw holding the fuel filter mounting bracket to the fuel filter, then remove the bracket.
15. Remove both of the fuel line clamps holding the fuel lines to the filter.
16. Loosen and remove the clamp holding the fuel pump output hose to the carburetor assembly. This is a bit tough to get to - you may have to remove the chrome carburetor cover on the right side of the engine. If you have difficulty locating it, follow the output hose from the fuel pump to the place where it fastens to the carburetor assembly. Gently twist and pull this hose free from the carburetor assembly.
17. OEM Honda replacement fuel filters can be found for $18 from Cyclemax Ohio. Until recently, I used Emgo fuel filters, which were a perfect replacement for the Honda filters, and were available for just a few dollars. However, as detailed in this thread about Emgo fuel filter failures, they have had serious quality control problems of late, and some resellers have reported that they have stopped making them. An acceptable replacement is the the NAPA model 3011 fuel filter, which can be had for a few dollars.
18. A benefit of the NAPA 3011 fuel filter is that it has a transparent case, which allows you to view the condition of the filter media, and to check for rust, sediment or debris.
19. The NAPA 3011 filter is slightly larger in diameter than the OEM filter. To get it to fit, partially tighten the bracket screw, and then insert the filter into the bracket until it is firm. Then tighten the screw a half-turn or so to secure the filter. Don't tighten it too much, so that the filter won't be damaged.
20. Because the screw won't be completely tightened, add a drop of blue Loctite to the screw threads, to prevent it from backing out.
21. There are three replacement hoses required: two 160mm in length (from the petcock to filter, and from the filter to fuel pump), and one 150mm in length (from fuel pump to carburetors). If you are using standard automotive 1/4" fuel lines, you can use a sharp knife to cut your hoses to this length, and skip below to step 28. In my case, I used stainless steel braided hose, which requires some more work to cut. The stainless braid will unravel if allowed to, so the ends are commonly fastened in place with electrical tape. Take a piece of shrink-wrap tubing and place it next to the electrical tape.
22. Use a heat gun to shrink the shrink-wrap tubing in place.
23. When finished, the shrink-wrap tubing should firmly grasp the braid, preventing it from unraveling.
24. Using a cut-off wheel, cut the hose near the end of the shrink-wrap tubing. A hacksaw can be used for this as well - but the end result will not be anywhere as neat. A cut-off wheel or similar power tool will cut through the braid and hose quickly, leaving a relatively clean cut.
25. Once the cut is complete, use a knife to trim the rubber hose, and diagonal cutters to trim any stray wires.
26. Repeat the process for the remainder of the hoses.
27. When complete, you should have two 160mm (16 cm) and one 150mm (15 cm) fuel lines.
28. While the existing hose clamps can be reused, new clamps are relatively inexpensive, and are cheap insurance against future problems. Ensure the clamps you purchase are of the correct size, of good quality, and made of stainless steel.
29. Thread the 150mm hose onto the carburetor barb. If you have difficulty, you can spray some WD-40 onto the barb to help lubricate it. Once pushed fully onto the barb, slide a clamp along the hose and tighten it in place. It is of critical importance that the clamp wrap around the hose at the narrow part of the barb, not the flared end. This will prevent the hose from pulling off the barb (as it won't be able to pull the clamp over the flared end of the barb).
30. Assemble the remaining two hoses onto either end of the fuel filter, then tighten a clamp over each end.
31. Push the fuel filter/hose assembly through the middle of the motorcycle, ensuring the filter is pointing the correct direction (in the case of the NAPA filter, the narrow side of the filter is the input side, and should be connected to the fuel petcock). Slide a clamp around the hose connector on that side, and push the hose onto the petcock barb. Tighten the clamp in place. Ensure the worm tab of the clamp (if any) does not interfere with the operation of the petcock.
32. Put two clamps over the remaining hoses, then push them onto the barbs of the fuel pump and tighten them in place.
33. Push the stud of the fuel filter bracket through the hole in the fuel tank tab, and tighten the nut over the stud. I recommend you use a drop or two of blue Loctite to fasten this nut in place - I have had this nut come loose due to vibration, even when tightened properly.
34. Replace the crankcase ventilation hose on the crankcase, and fasten its clamp in place.
35. Turn the fuel petcock on and check for leaks.
36. If you have installed the transparent NAPA 3011 filter, you will be able to see it fill with fuel.
37. Start the engine and allow it to run normally for a few minutes, checking for fuel leaks. Stop the engine, allow it to sit, and check again for leaks.
Important!
The fuel system on your bike is the most dangerous system on which to work! Most people take gasoline for granted. We use it every day in our cars and bikes, without a thought as to just how flammable and explosive it is, and just how much potential energy it contains.
It's extremely important that you double check all the fuel line fasteners you loosen or remove when working on the fuel system. When you're finished, go over the whole system, starting from the fuel petcock, and ending up at the carburetors, and ensure each fuel line is pushed completely onto its fitting, that the fasteners are in the correct place, and that the fasteners are tight and in good condition.
This is the result of a GL1000 owner who had a loose fuel line fastener remaining after working on their fuel system - don't let this happen to you!
