GL1000 Carb Button Design

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cfairweather
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Re: GL1000 Carb Button Design

#16

Post by cfairweather »

I decided to use TPU for the o-ring. You can research this filament and see what you think. It is tough, durable and resistant to fuel products. It is flexible and springs back to the same shape if you squeeze it. I like TPU and use it for many things. I just finished designing and printing some o-rings and they work perfectly. I made them where the slide is almost flush but sticks up a fraction of a millimeter. Over time, I can see it becoming flush as the ring fully seats. It prevents the metal to metal problem and the end of the shaft never touches the button. I will never build another set of carbs without installing these "shock rings."
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gltriker
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Re: GL1000 Carb Button Design

#17

Post by gltriker »

tumb2 An elegant solution there, Cedric ! tumb2

Sidecar Bob -
First time button failure was my fault. Gluing the #1 carburetor button fragment back in place was a sufficient remedy to regain proper carburetion function for 2 - ish years.
Second time, the engine was progressively running badly courtesy of an unrecognized carbon fouled catalyst element in the right side H-D muffler and my ignorance of the destructive effects it was physically registering (scorching) on the #1 carburetor's vacuum piston. (thankfully, the #3 carburetor wasn't injured )

Done tumb2
Cliff (74yrs ;) )

Keep your eyes and ears open and you'll learn something new, everyday. tumb2

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'75 GL1000 home built trike; http://www.ngwclub.com/forum/viewtopic.php?f=30&t=39996
October,2017 BOTM :shock: https://nakedgoldwingsclub.com/forum/page/Welcome

previous rides:
1953 H-D Servi-car, naked, 1969-1978 (serial#53G1559 committed to memory!)
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cfairweather
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Re: GL1000 Carb Button Design

#18

Post by cfairweather »

Over the past couple of days, I have been trying to find the optimal material to use as a cushion for the slide. As mentioned above, the cushion will fit around the slide shaft and sit at the bottom of the well. It only comes into play when the slide goes to the top. Robin pointed out the concern with the survival of the o-ring, so picking the right material is important. Due to the design, I doubt if much gasoline ever gets inside the slide well where the o-ring is located, but exposure to the gases is still a concern. I am guessing a Buna-N ring would be ok for years in that location and a Viton ring might last longer. There are better o-ring options, but they are more expensive and harder to find. Here are materials I found with better fuel resistance: FFKM, ETP, EPDM, TFE\P, FVQM, PTFE and there are others. PETG and Nylon filaments are also good choices for parts that are exposed to fuel. After further research, TPU might not be the best option. It would probably hold up about as good as Buna-N. Felt might be ok. I have narrowed it down to these four options:

1. Buna-N o-ring or the TPU ring I made. What is the worst case if they deteriorate? You will be back to the original Honda design without a cushion. So, maybe this simple solution is ok.
2. A nylon washer that is 1mm thick, 11mm ID and 15mmOD. You cannot make the washer wider than 2mm because it will cover the vacuum holes. I ordered some washers to test this idea.
3. A homemade leather or felt washer like the nylon washer. I have ordered some 1mm leather, felt and a punch kit to test this idea.

When using a washer, it really needs to be between .5mm and .8mm thick, but I should be able easily shave the nylon and leather down to the right thickness. This sounds like I am going to a lot of trouble on this little detail, but I am convinced this is important enough to come up with a reliable way to cushion the slide without having the button being a shock absorber.

This is the kind of stuff you have time for when you are retired... :)
redglbx
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Re: GL1000 Carb Button Design

#19

Post by redglbx »

CF, I believe you are looking at this correctly ! IMHO I think a nylon square cut washer would be the answer which would perform much like the nylon buttons on the 1100 carbs. Good luck & thanks for chasing this !
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cfairweather
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Re: GL1000 Carb Button Design

#20

Post by cfairweather »

RedGLBx- I agree that a nylon washer would work fine. Thanks for the vote of confidence :). Well, I think I might have accidently stumbled on to the best solution. Today, I was replacing felt seals; the ones that fit around the throttle shafts. I think these felt dust seals are 8mm ID X 12mm OD X 2mm thick if I recall correctly. Anyway, as I was replacing these seals, a "light came on." I thought it might be worth trying one of these felt seals on the slide shaft. I was so happy to see it was a perfect fit and it really is an ideal cushion for the slide. I don't think I will be able to improve on this, so I am done. If any of you would like to do this to your carbs, you can get 6 dust seals at Saber-Cycle for about $12.00. The slides almost sit flush in the venturi. Over time, the felt should settle and this will improve a bit.
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Sidecar Bob
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Re: GL1000 Carb Button Design

#21

Post by Sidecar Bob »

I don't like the idea of felt washers there. It wouldn't take long for them to pack down.
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Old Fogey
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Re: GL1000 Carb Button Design

#22

Post by Old Fogey »

First, my apologies for not getting back to you, CF. I have been struggling with health and computer probs for some time but I will try to get the info you wanted to you soon.
Your experiments mirror some that I did years ago, after I had a set in for repair that had one slide with the piston skirt broken off its guide pin. The button was also smashed. I concluded that a massive backfire through the carb was the cause.
It's a lousy design. If the plastic cap was intentionally designed as a 'soft' stop, no account was taken of the rigid aging effect on the plastic; and to chamfer the top of the guide pin down almost to a knife edge is perhaps the most inexplicable part.
I tried changing the button for an almost flat metal one (actually a auto core plug which is slightly concave) and grinding a fraction of material off the top of the guide pin, enough so that it hit the metal button just before the skirt hit the bottom of the guide tube which it also tapered, again reducing the contact area. That would have worked but I was not happy about the longevity of the metal button nor the sealing of it.
So I went down the route that you have finally found, putting an O ring or similar around the pin. That was Ok, but I never found a material that I was happy with (never tried felt, that's interesting.)
In the end I lost interest in the project, since that broken piston has been the only one in dozens of rebuilds and of course Pete came up with his new buttons.
The GL1000 carbs show the age of their design and some strange thinking; the first one year only carbs being the worst.
But Kei-Hin didn't get get the next generation, the GL1100 carbs, right either although they were a major improvement.
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cfairweather
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Re: GL1000 Carb Button Design

#23

Post by cfairweather »

Old Fogey, thanks for your message. Hope your health improves. I am going to attempt to make an injection mold. Maybe i will eventually get an injection system or make one. I wonder what happened to the mold that Pete had. Does anyone know the name of the company that he used to do the injection molding. They might make some more if they have a copy of the mold.
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Sidecar Bob
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Re: GL1000 Carb Button Design

#24

Post by Sidecar Bob »

I don't think the folks at Honda ever expected these bikes to last more than 10 or 15 years and the vast majority of the carb buttons appear to have lasted far longer than that.

I still think that automotive freeze plugs held in with screws and sealed with o-rings (see link below) is the best and most permanent way to replace the plastic buttons
viewtopic.php?p=432318#p432318

Perhaps a shock absorbing ring of suitably durable material around the shaft of the slide would be better than my discs of HDPE but it would have to be not only fuel proof (don't forget to test with E10) but capable of withstanding thousands of impacts without breaking down or compacting.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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Old Fogey
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Re: GL1000 Carb Button Design

#25

Post by Old Fogey »

I have to admit I don't think that felt will be the solution long term. By it's very nature, it is either (or both) going to compact or shred.
I think the best solution I came up with is to machine the entry of the guide tube flat and epoxy a metal cap over it with a rubber (Viton) or plastic buffer. It could be made significantly wider than an O ring or similar since it would only cover the holes in the skirt at full throttle. It could even be relieved to uncover the holes since the piston runs with a guide pin.
But again, in all honesty, it's mainly a solution looking for a problem, given how few pistons get broken or even relatively few buttons get smashed. It's simpler to replace the buttons, which incidently I am almost out of.
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cfairweather
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Re: GL1000 Carb Button Design

#26

Post by cfairweather »

Old Fogey, if you have one of Pete's that has not been installed, please take a picture of the top and bottom views for me. You and Sidecar might be right about the felt, but I believe it is dense enough that it will last a long time. Your solution is great but that is a lot of work. :) I think the felt will hold up better than a rubber o-ring, but time will tell. Even if it doesn't, I will be back to the original design, so there isn't much to lose.
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Old Fogey
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Re: GL1000 Carb Button Design

#27

Post by Old Fogey »

cfairweather wrote: Wed Dec 21, 2022 9:13 am Old Fogey, if you have one of Pete's that has not been installed, please take a picture of the top and bottom views for me. You and Sidecar might be right about the felt, but I believe it is dense enough that it will last a long time. Your solution is great but that is a lot of work. :) I think the felt will hold up better than a rubber o-ring, but time will tell. Even if it doesn't, I will be back to the original design, so there isn't much to lose.
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Wingnut1000
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Re: GL1000 Carb Button Design

#28

Post by Wingnut1000 »

Excellent work CF, You are an asset to the GW community with all your brilliant deductions. The shaft felt as a cushion was a very resourceful thought you had, as well as pursuing the source of the Pete Boody buttons. Nice work!!
cfairweather
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Re: GL1000 Carb Button Design

#29

Post by cfairweather »

Thank you for your kind words. The 3D buttons I print are very good quality and will work fine, but Pete's are better because he had an injection molding company make them. His are just like the originals and I bet he sent an original to the company and had them make the mold. This is expensive. The problem with making the button the same diameter is getting it in the hole and most people would not be able to do it without screwing up the cap. I am not sure, but I believe to install his, you must pry up the lip about half way around to get the button in the hole. The ones I make will be easy to install because they are a bit smaller in diameter so they can be pressed or tapped into place. I designed a mold last night and will 3D print it today. Then I will work on making the mold out of aluminum. Then all I need is an injection system. I can make a simple one and have most of the parts but I have my eye on a Pneumatic system that would be better. My goal is to have a button kit with most everything a person needs to do this task that can be sold on eBay for about $50.00. I am not looking to make a lot of money selling these but I need to recover my costs.
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Re: GL1000 Carb Button Design

#30

Post by 5speed »

Threads like this are what make this site so awesome..
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