There are actually two more air filters that need servicing on a regular basis:
Sub air filter
The sub air filter is a foam filter that filters the air before it reaches the air injection solenoids, and from there the carburetors. This filter tends to deteriorate and fall apart, sending foam particles through the solenoids and into the carburetors. This can cause poor performance and carburetor problems. The part number for the filter is 17253-KT8-000 and it can be purchased from vendors such as Cyclemax for around $3.
Cruise air filter
The cruise air filter is also a foam filter, that filters the air before it reaches the solenoids that control the cruise control. The part number is 36532-MN5-005, and it too can be purchased from vendors such as Cyclemax for around $3.
Unfortunately, reaching both of these filters involves a bit of disassembly. No problem though, we'll walk you through the steps.
1. First off, if you have any accessories that need to be removed before you can remove the lower cowls, do so now. In my case, I have a set of wind wings that I need to remove.
2. I also have a set of air horns that need to be disconnected, loosened, and pivoted out of the way.
3. Gently pull the inner edge of the lower cowl screw cover away from the screw head.
4. Be very careful removing these covers - pulling them back too far will snap the tab off of the outer edge. See how the tab hooks into the cowl. Gently rotate the inner edge back, then pull it straight out.
5. Remove the lower cowl screw.
6. Gently remove the lower cowl deflector. It pulls out approximately one inch at the bottom, then is pulled straight down to disengage the top tab, then is pulled straight back to disengage the front tab.
7. This is the top tab that needs to be disengaged.
8. And this is the front tab.
9. To remove the fairing front cover, press inward at the center of the top of the cover. This will expose the posts seated in the grommets at the top corners.
10. Gently pull the top corners away, one at a time, to unseat the posts from their grommets. Note the black tab that is holding the front of the lower cowl in place - it's important that the lower cowl is fitted back behind these tabs when it is replaced.
11. Once both posts are unseated, remove the front cover.
12. Remove the screws on either side of the under cover.
13. While holding the under cover in place, remove the center screw.
14. Pull the under cover away.
15. The side marker light trim needs to be removed next. OEM Honda trim is black plastic and looks different than my aftermarket chrome trim. My trim has screw caps that must be removed to access the screw heads.
16. Remove the three screws holding the trim and the marker light in place.
17. Once the screws and marker light are free, the lower cowl will easily pull away. If you have cornering lights, press the locking tab on the connector and disconnect the cornering light wire. Repeat steps 15 and 16 to remove the lower cowl on the other side of the motorcycle.
18. Remove the right side cover. Start by pulling the bottom front post free from its grommet.
19. Next pull the bottom rear post free. Pull the bottom slightly toward you - but not too far, or you risk snapping off the remaining post! Pull the cover free from the metal post at the top front, then gently work the top rear post free of its grommet, and pull the side cover away.
20. Pull the front side cover free of its grommet.
21. Pull the front side cover to the rear to disengage its locking tab, the pull it away from the bike. Repeat steps 18 through 21 to remove the left side covers.
22. Remove the seat as described in How to remove and replace your seat.
23. Remove the soft cover from the left fairing pocket, then remove the four screws holding the pocket in place.
24. Lift the pocket out of the fairing. If your pocket has a 12 volt outlet in it, you may need to disconnect it - or just let the pocket hang out the side by the wires.
25. Unlock and remove the hard cover from the right fairing pocket.
26. Remove the four screws holding the right fairing pocket in place.
27. If your GL1500 is an SE, you will have a knob for the foot warmers. You'll need to remove the set screw for this knob, then pull the knob off in order to get the pocket out.
28. Remove the pocket from the fairing.
29. Remove the ignition switch cover by gently pulling up at the bottom as shown until the posts disengage from the rubber grommets. Then release the tabs at the top and remove the cover.
30. Remove the left top inner cover by pulling the tab free at the rightmost edge as shown.
31. Follow by pulling each tab free in sequence until you get to the front tab.
32. This tab locks in place - be careful not to break it. Next, remove the right top inner cover the same way as you removed the left side.
33. Open the fuel filler door and identify the two plastic locking tabs near the front of the opening.
34. Rotate the tabs as shown to unlock the radio shelter.
35. Using a 10mm wrench or socket, remove the two acorn nuts holding the back end of the radio shelter in place.
36. Release the tabs at the front left and right sides of the radio shelter from the fairing.
36. Lift the back end of the radio shelter free of the studs. The reason for lifting the shelter is to release the fairing rear side panels. The radio shelter does not need to be fully removed in order to do this - simply lifted up. Put a tool, block, or other small object under the radio, to keep the radio shelter lifted several inches, to give access to the fairing rear side panels. Note that in the pictures that follow, the shelter is actually removed, to allow better access for photographs.
37. Peel back the rubber cover from the back of the reverse lever (if equipped). Insert a hex driver or allen key and remove the hex bolt fastening the reverse lever to the bike.
38. Remove the reverse lever from the bike.
39. Pull the side trim off of the fairing rear lower cover on both sides.
40. Remove the two screws fastening the top of each of the left and right fairing rear lower covers in place.
41. Using a wrench or a deep 10mm socket, remove the studs from the side of the fairing rear lower covers.
42. Remove the screw from the front side of the fairing rear lower covers.
43. Pull the left fairing rear lower cover free. Peel back the rubber boot of the CB connector, depress the locking tab, and pull the connector free. Pull the antenna connector free. Always pull on the connectors, never the wires! Set the left fairing rear lower cover aside.
44. Pull the right fairing rear lower cover free. Depress the locking tab of the air pressure console and pull the connector free. Set the right fairing rear lower cover aside.
45. Time to start changing filters! With a 10mm wrench, loosen the sub air filter housing bolt, located on the right side.
46. Remove the filter housing. The hose can be left connected, but try not to bend it too sharply.
47. Depress the locking tabs on the housing and remove the bottom to expose the old filter.
48. Remove the old filter. You can see that as soon as I removed this filter, it crumbled in my fingers.
49. The new filter needs to be soaked in oil before installation. The gear oil used in the final drive is a good oil to use, failing that, regular engine oil will work as well. Saturate the filter with oil, then squeeze it out until it is no longer dripping.
50. Reinsert the new filter into its carrier and snap it back into place.
51. Replace the sub air filter housing and tighten the retaining bolt.
52. Locate the cruise solenoid valve assembly, on the left side. The cruise filter is contained within the "L" shaped piece at the back.
53. Pull the filter housing free of the solenoid valve assembly.
54. Pull the old filter out, and push the new filter into the housing in its place. This filter does not require oiling.
55. Snap the filter housing back into place.
56. Reconnect the air pressure console and replace the right fairing rear lower cover. Make sure that when the cover is put into place, that the lever assembly that controls the hot/cold setting of the lower air vent properly engages the pin that actuates the blend door.
57. Reconnect the CB main and antenna connectors, and replace the right fairing rear lower cover. Make sure that when the cover is put into place, that the lever assembly that controls the hot/cold setting of the lower air vent properly engages the pin that actuates the blend door.
58. Replace the screw on the front side of the fairing rear lower covers.
59. Replace the studs on the sides of the fairing rear lower covers.
60. Replace the screws fastening the tops of the fairing rear lower covers.
61. Replace the side trim off of the fairing rear lower cover on both sides and press into place until it locks.
62. Replace the reverse lever (if equipped). Make sure the lower pin in the (shown in the picture) fits into the hole below the threaded area before engaging the bolt in the crank. Also make sure the two "teeth" on the lever fit snugly and fully into the cutouts on the crank.
61. Tighten the lever into place, making sure the teeth seat fully into the crank cutouts. Replace the rubber boot over the back of the lever.
62. Pull out the block or support that is keeping the radio shelter raised, and lower it over the studs.
63. Make sure the locking tabs are still in the inward (unlocked position).
64. Replace and tighten the acorn nuts to hold the shelter in place.
65. Now rotate the locking tabs outward to lock the shelter in place.
66. Make sure the tabs at the front left and right sides of the radio shelter insert into their slots in the fairing.
67. Insert the front tab of each inner cover into the dashboard.
68. Gradually work around each inner cover starting at the front and working your way around to the inner back, putting each tab into its slot.
69. Replace the ignition cover by inserting the front tabs into their slots, then rotating the back down into place, pushing the posts into their grommets.
70. Replace the right fairing pocket and screw it into place.
71. If equipped, reinstall the foot warmer knob and its set screw.
72. Reinstall the left fairing pocket and screw it into place. Make sure the intercom lead wire is positioned correctly in the pass-through before screwing it into place.
73. Reconnect the cornering light connectors in the lower cowls (if equipped). Place the lower cowls back into position. Ensure the innermost tab (with the hole in it) fits behind the black tab protruding down from the radiator grill mentioned in step 10. This holds the front of the lower cowl in place.
74. Replace your side marker light and trim, and screw it into place.
75. Replace your screw caps (if you have them).
76. Replace the lower cowl deflector. Insert the front tab first, then the top tab, then slide the deflector to the left to line up the screw holes.
77. Tighten the lower cowl screw.
78. Replace the lower cowl screw cover - insert the tab first, then press fit it over the screw head.
79. At this point you would repeat the procedure on the other side of the bike. Once that is complete, lift the under cover into place.
80. Insert the center screw to hold the under cover in place.
81. Ensure the posts at the front, on the bottom of the lower cowls fit into the holes on the top of the under cover (visible at the front edge where the lower cowl and under cover meet) - on both sides! Once the posts are in place, replace and tighten the screws on either side.
82. Make sure the tabs at the bottom of the front cover fit behind the ridge of the under cover, and that the tab on the bottom center of the front cover fits into the slot in the under cover. Align the front cover, then press the posts on either side into their respective grommets.
83. Push the forward side cover's tab into its slot, then push it into its grommet.
84. Replace the side cover, starting at the top, then pushing the lower posts into their grommets. Repeat steps 83 and 84 for the other side.
85. Replace the seat as described in How to remove and replace your seat.
