Important Honda GL1100 Carb Details

You might consider this item: GL1100 Carburetor Repair Manual written by noted GL1100 guru Howard Halasz

This Tech Tip is provided courtesy of Howard Halasz – noted GL1100 Guru. Howard is a frequent contributor of technical columns and other information to GWRRA’s Wing World Magazine.

GL1100 Accelerator Passage

“Randakk’s GL1100 Master Carb Overhaul Kit includes are the pieces needed to address the details below during a comprehensive overhaul.”

Plenum Details:

“The main GL1100 carb-to-plenum FUEL seals (large) are identical to the GL1000 carb-to-plenum FUEL seals that come in Randakk’s GL1000 Master Carb Overhaul Kits. There are also two smaller carb-to-plenum FUEL seals for the accelerator pump circuit.

Only two main carb-to-plenum seals are needed and only two accelerator pump carb-to-plenum seals are needed when rebuilding the GL1100 carbs.

NOTE: The two main FUEL seals go on carbs #2 and #3 only and the accelerator pump seals go on carbs #3 and #4 only. The fuel joint pipes will supply main and accelerator pump fuel between carbs #1 and #3 and between carbs #2 and #4. Too many people will put extra seals on the GL1100 carbs in other spots where they’ll fit, but they are not needed.

If you put the fuel seals in the two carbs that don’t need them and leave them out of the carbs that do need them, you’ll end up with major fuel leaks all over the top of your crankcase.

Here are photos showing the correct location of these vital seals:

Randakk's Carb Details

Left – carb #2 and carb #4 (left carbs viewed from plenum) Right – carb #1 and carb #3 (right carbs viewed from plenum)

Blue Arrows – main fuel seals (main fuel channels) Yellow Arrows – small fuel seals (accelerator circuits)

Note: the side of these special “U” fuel seals with the radiused profile is installed facing the plenum. The flat side of the seals goes toward the carb bodies.

Accelerator Channel “Straw:”

Don’t forget where the little plastic straw goes! The plenum halves have a plastic straw that slides into the accelerator pump fuel crossover channel at the bottom of the plenum halves.          
Accelerator Channel "Straw:" Blue Arrow – Location of Accelerator Channel “Straw” (#1/#3 carb side)

Accelerator Channel Straw

Left Photo: View of Accelerator Channel “Straw” (#2/#4 carb side) Right Photo: Location of Channel

Notice the new plenum gasket and the 2 locating dowels installed on the plenum in left photo.

Put the straw where the blue arrow points. This is the accelerator pump fuel channel…the rear-most channel on the bottom of each plenum half.

The straw is vital. It is necessary is to regulate pressure/flow in the accelerator pump circuit. The purpose of the straw is to reduce the volume of the crossover channel so that you don’t have to work the throttle a million times to get fuel to travel from the accelerator pump in carburetor #3 to the nozzles in the other carburetors. This is particularly important after short lay-ups have allowed normal evaporation of fuel.

GL1100 Accelerator Straw

OEM “Straw” Dimensions:

Length = 73.25 mm

Outside Diameter = 3.95 mm

Inside Diameter = 1.85 mm

 The straw is not available from Honda. If your straw is lost or damaged, I now supply beautiful reproductions in brass:

Randakk GL1100 Accelerator Straw

Randakk Reproduction GL1100 Accelerator Channel “Straw”

Fabricated in Brass. Details here.

 

Pucks:

“GL1100 carb pucks are pressed in. Do NOT try to remove them!!!”

Idle Jets:

“GL1100 carbs had two different types of idle jets. The ’80 and ’81 carbs have the idle jets pressed into the carb bodies while the ’82 and ’83 carbs have removable idle jets. Do NOT try to remove the pressed in idle jets!!! They must be cleaned in place.”

Removing Stubborn Idle Mixture Screws:

Another problem you may come into when working with GL1100 carburetors is dealing with idle mixture screws that seem to be super glued into the carburetor bodies. They don’t always come out as easily as the GL1000 carb idle mixture screws do. If one of those screws has a broken tip that has wedged into the carb body, then that carb body can be considered trash.

Rarely have I been able to save a GL1100 carburetor with a broken idle mixture screw tip stuck in the idle orifice. There have been several occasions where I had to use a thin cutoff wheel and die grinder to cut a screwdriver slot into a broken idle mixture screw. Then a flat blade screwdriver usually gets the screw out.”

Idle Mixture Screw Details:

When you remove the idle mixture screws for cleaning, don’t neglect to fish out the small O-ring and washer beneath the spring. Often, they will stick in the carb body. If you don’t get them out, the idle mixture can’t be set properly and you will probably damage the fragile tip of the idle mixture screw. You can fashion a handy removal tool from a bent paper clip.

When you install these, the spring goes onto the idle mixture screw first, followed by the washer and then the O-ring”

GL1100 Idle Screw        Correct orientation of GL1100 idle mixture screw, spring, washer and O-ring shown above

Float Level:

The procedure for setting the float levels on GL1100 carbs is essentially the same as the one for GL1000 carbs described here. The only difference is that the float level spec for the GL1100 is 15.5 mm.”

Fuel Transfer Tubes:

Complete disassembly is required to renew the o-rings on the main fuel transfer and accelerator fuel tubes. Don’t skip this step! When rejoining the carb pairs to each other be careful not to bend or distort the soft aluminum tubes. The tubes on the left and right sides are identical.”

Fuel Transfer Tube

“Also, take special care to make sure that the throttle arms are joined with a washer on either side of the arm. Synchronization will be corrupted if both washers end up to one side of the throttle arm. Be sure to put the 2 springs back between the throttle shaft ends as shown photo above. Rejoining the choke shafts is easy on GL1100 carbs because there are no annoying connectors as on GL1000s.”

Air Jet Cover / Guides:

These are secured with 4 x 16 mm screws which are the same size as the float bowl screws. Unlike the GL1000, there are no gaskets under these.”

Air Jet Covers                  4 x 16 mm screws secure the air jet cover / guides

Air Cutoff Valve Rebuild:

“The process is simple and intuitive, but it is all but impossible unless the carbs are completely separated. Unlike the GL1000 carbs, these diaphragms can’t be installed upside down. Be sure to chase all 3 air circuits into each valve chamber to verify that they are clear. Once the individual carb bodies are cleaned and prepped, install the new air cutoff valve kits before the carbs are rejoined to each other and the plenum. The air cutoff valve covers are secured with 4 x 12 mm screws.
On rare occasions, the metal actuating knobs on air cutoff valves are slightly too big for the GL 1100 carb bodies. Check these for fit. If necessary, lightly polish the knobs on the air cutoff valves with a mill bastard file until they fit the carb bodies without sticking.

Fuel Inlet Barb:

Most people overlook this small detail. The inlet fuel barb has 2 o-rings secured by retainer bracketry which doubles as part of the accelerator pump linkage. The required o-rings are the same exact size that are used for the main fuel transfer tubes. Randall includes all of these bits in his GL1100 Master Kit.”

Fuel Inlet

CV Slide Top Limit Plug:

Be sure to replace the O-ring on the plastic CV slide top limit plug with the new O-ring from your rebuild kit. 

CV Slide Top Plug

If you are a professional mechanic or have lots of carb parts from various bikes on your workbench, be very careful that you don’t mix these innocent looking parts. Be aware that Honda used different length CV slide top limit plugs on various Honda models of this vintage even though they are all in the same carb “family.

For example, look at the pictures below…the GL1100(left) uses a CV slide top limit plug that is 10.95 mm tall while the nearly identical part from a CBX carb (right) is 16.47 mm tall. A GL1100 with CBXCV slide top limit plugs would not be able to achieve full power as the CV slides would not rise completely under full throttle.GL1100 CV Slide Top Limit Plug

GL1100 CV slide top limit plug (left) – 10.95 mm tall

CBX CV slide top limit plug (right) – 16.47 mm tall

Usually the CV slide top limit caps will pull ring out. They are simply pressed in (by hand) and have an oring seal. If they are really stubborn to remove, they probably have fuel residue that has effectively glued them in place. You can overcome that 2 ways:

1. Boil the carbs in distilled water like this.

2. Carefully heat the area beneath the cap (piston aspect) with a Bic lighter or similar. Let me emphasize carefully…with recognition of the safety hazards of having an open flame near anything flammable.”

CV Slide Cushion Rings:

The CV slide cushion rings are installed with the ridge facing UP as show in the photo.

GL1100_CV_Slide_Cushion_Ring

Install with ridge facing UP

Again, if you are a professional mechanic or have lots of carb parts from various bikes on your workbench, be very careful that you don’t mix these with slide cushion rings from other models.

Another comparison to the CBX…the GL1100(left) uses a CV slide cushion ring that is 2.0 mm thick while the nearly identical part from a CBX carb (right) is 3.0 mm thick. A bike with the wrong slide cushion rings would have serious idle problems!”

GL1100-Slide-Cushion_Ring

GL1100 CV slide cushion ring (left) – 2.0 mm thick

CBX slide cushion ring (right) – 3.0 mm thick

Accelerator Pump Details:

Install the accelerator dust boot “groove” into the hole in the body of carb #3 as shown before you install the rebuilt float bowl / accelerator pump assembly.”

Accelerator Pump

“Lightly lube the pump rod and insert the rod through the boot making sure the boot remains in position. Be sure the special O-ring is in place adjacent to the float bowl gasket. A slight smear of vaseline will hold it in position.”

GL1100 Pump Rod

The O-ring shown below seals the accelerator fuel passage from the pump to the main carb circuits. Be sure the O-ring stays in place during assembly. Again, A slight smear of Vaseline will hold it in position. Randakk’s Master GL1100 Carb Overhaul Kit even includes an extra spare for this O-ring which often lost or misplaced.”

GL1100 O-ring

Carb #3 only has an opening in the carb body for the accelerator fuel path (shown below). The other 3 carb bodies have pressed in brass plugs in that location. Do not attempt to remove these brass plugs.”

GL1100 Accelerator Passage

Accelerator Pump Adjustment:

Adjust the accelerator pump before installing the carburetors on the Gold Wing. Measure the clearance between the adjusting arm and the stopper on the carburetor body. The specified clearance is 10 mm (0.4 in). Adjust it by bending the adjusting arm. See photo below.”

GL1100_Pump_Adjustment

Float Bowl Details:

Be sure to use three 4 x 16 mm screws to secure each float bowl. If you mix up the screws, and use the 4 x 12 mm screws intended for the air cutoff or accelerator pump cover, you risk stripping the threads in the carb body as these screws are too short for the job!

Also, be sure you orient the float bowls correctly as shown in the photos below. It’s impossible to get the float bowl for carb #3 in the wrong spot since it contains the accelerator pump. But, the others can be mixed up. The correct placement results in the float bowl drain screws oriented inboard. This makes subsequent fuel bowl draining much easier.”

Howard Halasz, Wing World Technical Contributor – Houston, TX

GL1100-Carb-Adjustment

You might consider this item: GL1100 Carburetor Repair Manual written by noted GL1100 guru Howard Halasz

Comments

  1. I have a a real head scratcher; I have an 83 gl 1100 with 40K on it didn’t run on arrival and new timing belts later it will run. I went through carbs and now it will seemingly run fine out to about 5,000 rpm and then you have to choke hell out of it to get any more. Have gone through carbs until I am blue in face and can’t find problem. I do not have the rubber plugs that came with the carb kits installed and am wondering if that could be my problem. Any suggestions would be greatly appreciated.

  2. Hello Randakk, I have an 1982 Honda Goldwing Gl1100 I picked up from a person who was over their head in reassembling the bike. I am a master Mechanic in the automotive field of over 41 years. I have not worked on Motor cycles before but then there are many automobiles I have never worked on also. I got this bike disassembled and have come along way from where I started. This bike has sat many years with old fuel in system. Fuel tank was cleaned, carbs overhauled due to external fuel leaks, (jets plugged up) and it runs pretty good. I have replace fuel pump with new Honda pump and the fuel pressure is good cold. But when the engine is warm the pressure drops below 2 psi. Sometimes it is below .5 psi. It does loose power and doesn’t want to accelerate with a load. I can clear it out revving without a load. I noticed this especially when the pressure was low. Today I noticed the same lack of power under load and accelerating. I was necessary to down shift. The pressure was about 1.8 psi. Again the pump is new, the carbs have been gone through 5 times with the most improvement the last time with float replacement. Cold pressure this morning was 2.4psi. A few minutes in the ride, it dropped below 2.0 psi. I have ordered an electric fuel pump rated 1-4 psi. I am not sure if this will work. I also noticed about the tube cross over for the accelerator pump. I remove this the first time I went through the carbs. Will this cause a loss of power during the heavy acceleration up hill? I have a semi permanent fuel pressure gauge installed in pressure side of pump so I can monitor fuel pressure when it acts up. I am scratching my brain here.

    • Thoughts.

      I suspect either your new pump is defective (happens) or your gauge is very inaccurate. I would bet that the pump is bad.

      • Check your gas cap make sure the vent is working on the gas cap sounds like your vapor lock or have a vacuum on your tank or you’re running the longer you run the more vacuum in the tank

  3. Any idea when the fuel straw will be available again. I seem to have misplaced mine and tracking down brass tubing is crazy hard. I can either find the right outside or inside diameter but not both. I have a tube cutter and know how to make these. Any help will be greatly appreciated.

  4. So Grateful for these Essential Pointers for Reassembly, especially where that “straw” goes. Nothing like the customer insisting, against my STRONG recommendation that your kit be the one we go with, on getting a cheepass kit from eBay that – no surprise – had components that did not fit. Of course in the Weeks that elapsed between taking the suckers apart and FINALLY getting your kit, I had forgotten where some of these things go. And then there’s the Proper location of the carb-to-plenum fuel circuit O rings. Boy, that would’ve sucked had I gotten that wrong. Thanks again!

  5. Robert Q. says:

    1. Thanks for the grinding wheel tip on how to get a stubborn, broken idle mixture screw out. Worked great for me, and i have just reused that screw with the new slot cut in it. No problems at all with it.

    2. Have replaced head gaskets every 6 or 9 months for years (with an expensive head rebuild each time) because the gaskets (OEM) have been chewed up on the engine side between the cylinder sleeves. The shop that rebuilds the heads (cyl. head rebuilding is their business) tells me this is due to early spark or air leak. Both heads and block are flat. Properly torqued. OEM head gasket. I’m a Christian. Have not been kicking the dog.

    Since spark is electronic (1981 GL1100), and the vac. hose to the “points” (not points, I know) maintains vac. (neither hose or diaphragm leaking), I’ve presumed air leak. With my synchronizer the vac drawn at idle is VERY low (5 or 6 or 7 psi, changes as it should with throttle).

    Found with brake cleaner there is a big air leak at the throttle shafts of both rear crabs. Rebuilt the carbs 5 or so years ago, but could not remember anything about seals. So, was about to see if there was some way to replace the seals in situ (since the carb assembly is such a PITA to remove), but then saw your post showing these carbs have a hole and intentional air “leak” at the shaft.

    So now I’m stumped. No other leaks seem important enough to change idle speed when sprayed.

    Blow the bike up?

  6. I’ve got a fix with the broken mixture tip problem. For my bike, I had a new mixture screw fabricated with modified dimensions so the end fits into a 1/16″ hole, with a tapered tip. It uses the same spring and washer arrangement as original. This allows you to drill out the broken tip using a 1/16″ drill bit. Then use the re-designed mixture screw (with the modified “fatter”/tapered end).

    It saved my carb. Nobody should have to get rid of an otherwise good carb body because of this problem. I can get the dimensions or mixture screws to you.

Trackbacks

  1. […] definitely need the "straw." It's function is explained here: http://www.randakksblog.com/gl1100-carb-details/ __________________ Randall Washington (Randakk) Randakk's Cycle Skakk, LLC Winston-Salem, NC […]

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