1975 GL1000 755A Carb linkage step-by-step fix

Post your "How To", or share tips and tricks about maintenance related to four cylinder Wings. Only registered users can read this forum.

Moderators: Whiskerfish, Forum Moderators

Post Reply
cfairweather
Silver Member
Silver Member
Posts: 774
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

1975 GL1000 755A Carb linkage step-by-step fix

#1

Post by cfairweather »

1975 GL1000 755A Carburetor Linkage Issues and step-by-step instructions to fix it
This step-by-step instruction document will be in three posts because I am limited to 5 pictures per post.

The original 1975 design uses “ball and cup” joints and the later models use shaft and bushing joints. The “ball” joints introduce wobble and slop which makes it more difficult to keep the 4 carbs in sync. Let me say that while doing this project, I learned there is a lot of precision built into the original design, even though it didn’t work out for Honda.

My goal was to make the 755A linkage as good or better than the later design and I succeeded. In doing this project, I tried many possible solutions. While all of the methods I tried improved the linkage, one method stood out as a clear winner. I am going to skip all of the things I tried and only talk about the solution that worked the best, a tiny modified M3 nylon flange nut. The best time to do this modification is when you rebuild your carbs.
DSCN5329.JPG
Let’s first discuss the original parts:
There are two linkage arms, one short and one long. The joints are all the same. The arms attach to steel pins that have a ball in the middle. The arms have a smaller 5.31 (.209 in bit size #4) hole on one side and a larger hole 6.15mm (.242 in bit size C) that fits over the 5.85mm ball. Two cups hold the arm in place and one of these has a spring behind it. You will also notice there are two tiny holes on the linkage and you won’t see these because they are on the underside when installed correctly. These look like drain holes but they are actually for prying out the cup. There is a black spacer washer that is permanently fitted over the ball; however, this washer is often brittle, broken or missing after 50 years. Note: The permanently mounted black washer that fits on the shaft can be replaced with a nylon M4 X 10mm X .5mm washer. You will have to cut the washer and then work it onto the shaft. The slit will not negatively affect the linkage operation as it is simply a spacer and prevents metal-to-metal contact and helps prevent wobble. Here is a source: https://www.ebay.com/itm/176062536916?var=475581960471

There is also a plastic washer and an e-clip to keep the arm in place. The e-clip is hard to find because the groove is about 1.7mm in diameter. The shaft is 4mm in diameter on the side with the washer and 3mm on the other side of the ball where the e-clip goes. The 6mm hole is offset slightly to allow easier installation of the arm.

Tools and items needed:
1. 4ea M3 nylon flange nuts.
2. A 5mm nut driver or socket. The M3 nylon flange nut will be modified using a modified 5mm nut driver or socket. The modification is simple; just use a #3 drill bit and drill out the end. You also need to make the end flat using a file. This will be used to make the nylon nut round and it will be the perfect size.
DSCN5330.JPG
3. A drill and a Dremel with 5mm (est) ball file.
DSCN5334.JPG
4. Vise
5. 10mm wrench or a vice for holding the arm when tightening/loosing the 9mm cap ends
6. 9mm socket for removal of the spring and cup cap.
7. Super glue
8. Drill bits: #3, #4, #31
9. A M3 Screw. The head will be removed.
10. Tiny screw driver and dental pick to remove e-clip


Procedure:
1. The first thing you need to do is remove the arms from the carbs. Then use your 9mm socket and remove the caps from each end. Remove and clean the spring/cup caps from each end, then put these aside in a safe place as we will reinstall these later.
2. Remove the head of a M3 screw and then place the cut end into your Dremel. 5 or 6 threads should be sticking out of the end. When you install the nut on the screw about 1mm of the threads will not engage. We will be using the length of the screw to resize the thickness of the nut. So, the nut will be initially stick out about 1mm beyond the end the screw.
DSCN5331.JPG
DSCN5333.JPG
Continued in next post...
You do not have the required permissions to view the files attached to this post.
cfairweather
Silver Member
Silver Member
Posts: 774
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: 1975 GL1000 755A Carb linkage step-by-step fix

#2

Post by cfairweather »

3. Put the modified 5mm nut driver in a vice. If you have not modified it, do that first.
4. Mount a M3 nylon flange nut on the Dremel, turn it on, and push the nut into your resizing tool. Next, we will use the Dremel as a mini lathe to remove the melted plastic and trim the thickness of the nut.
DSCN5335.JPG
5. I recommend a craft knife to get the melted plastic off. Use your knife and “mini lathe” to trim the thickness of the nut down to the length of the screw. The thickness of the bushing will be about 2.7mm.
DSCN5338.JPG
It is critical to get all of the melted plastic off so the new bushing is perfectly clean. Finally, insert the nut into the resizing tool one more time and you will have a new bushing. Remove the bushing from the Dremel. You will need 4 of these, so repeat the above steps before going to then next step. Tip: You can use this same idea to make hard to find shoulder bushings.
6. Place one of your linkage arms on a workbench and prepare to install a bushing. The short linkage has one small hole on each side and the long arm has both small holes on the same side. The bushing will be a tight fit and we will glue in too. We do not want it to move. Put a tiny amount of super glue around the face of the small hole. Now place the bushing into the hole and use plyers to press the bushing into the hole. Let the glue set for several minutes.
DSCN5340.JPG
DSCN5341.JPG
7. Using a #31 drill bit, drill out the bushing. Make sure you drill a straight hole. A drill press will help, but is not needed.
8. Now we need to clean up nylon on the inside of the joint. I recommend first using a #4 bit and you can do this with or without a drill. Just carve out the excess nylon so it won’t interfere with the spring and cup. You need to be careful not to touch metal when using the #4 drill bit. We only want to remove excess nylon, not metal. Then insert the round Dremel ball file (about 5mm) to form a smooth, tiny cup on the nylon bushing. Finally, you need to run the #31 bit through the hole for one last time. Make sure the entire shaft of the bit goes into the bushing to ensure a perfect size. Don’t forget to clean out the joints before you reassemble. I also recommend a small dab of grease for the cups. Tip: When installing the arm, use a dental pick through the bushing to get the cup out of the way.
DSCN5343.JPG
You do not have the required permissions to view the files attached to this post.
cfairweather
Silver Member
Silver Member
Posts: 774
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: 1975 GL1000 755A Carb linkage step-by-step fix

#3

Post by cfairweather »

Continued from previous post...
DSCN5347.JPG
DSCN5345.JPG
Install the clip without a washer because the bushing flange is basically a washer. There will be no room for a washer.
You do not have the required permissions to view the files attached to this post.
User avatar
Fred Camper
Vice President
Vice President
Posts: 7157
Joined: Wed Aug 12, 2009 9:38 pm
My Album: http://www.ngwclub.com/gallery/v/wingmans/Jeff+Bozeman/
Location: Metro Detroit
Contact:

Re: 1975 GL1000 755A Carb linkage step-by-step fix

#4

Post by Fred Camper »

Nice thread with lots of documentation. Looks to be a good addition to shop talk if others agree.
Proud member of the NGW Cartel (Rochester MI)
1977 GL1000 BADDOG (April 2012 BOTM)
1976 LTD - '993 LTD...and so it begins'

You should remember that it's peace of mind you're after and not just fixing the machine. R.Pirsig
User avatar
CYBORG
Moderator
Moderator
Posts: 24833
Joined: Mon Jan 14, 2008 12:52 pm
Location: Muskegon mich

Re: 1975 GL1000 755A Carb linkage step-by-step fix

#5

Post by CYBORG »

Fred Camper wrote: Fri Jan 31, 2025 11:05 am Nice thread with lots of documentation. Looks to be a good addition to shop talk if others agree.
I agree.
1978 custom GL1000
1977 custom with 1200 engine
1985 gl1200
cfairweather
Silver Member
Silver Member
Posts: 774
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: 1975 GL1000 755A Carb linkage step-by-step fix

#6

Post by cfairweather »

Thank you. I have decided to share an alternate option to this fix for those that don't mind drilling a larger hole in the linkage arms. This option is actually easier and uses an aluminum bushing; however, it does require you to drill out the small hole to a sightly larger diameter.
cfairweather
Silver Member
Silver Member
Posts: 774
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: 1975 GL1000 755A Carb linkage step-by-step fix

#7

Post by cfairweather »

I decided I would provide an alternative option for those that don't mind drilling out the small holes on the linkage arms. If you do this, it will allow you to insert an aluminum bushing and this is probably the most durable option. I use JB Weld to glue in the bushing. It is really simple, just use a #3 drill bit or a drill bit that barely allows you to insert in a 3.1mm X 6mm X 2mm aluminum bushing. I use JB Weld to glue them in but you must be careful to get all residue out of the joint. You may need to create a cup with the Dremel tool as previously discussed. The E-Clip is hard to find. Tip: The same size clip is used for the needle jet on a SOHC CB750. Here is a link to buy them: https://www.dimecitycycles.com/keihin-n ... idual.html

With the aluminum bushing option, you will need to use a washer (spacer) before installing the clip and the thickness will be between .50mm and 1mm. Use the thickest spacer washer to ensure the linkage has a sung fit to prevent any wobble.

Here are some pictures:
DSCN5349.JPG
DSCN5350.JPG
DSCN5351.JPG
You do not have the required permissions to view the files attached to this post.
Post Reply
  • Similar Topics
    Replies
    Views
    Last post

Return to “How To 4-Wings (Tutorials Only)”