GL1000 carb top repair/reinforcement?

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SMLE
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GL1000 carb top repair/reinforcement?

#1

Post by SMLE »

I searched, but didn't find anything useful.

I just had a carb top fail on me nd I was wondering if there was an effective way to repair the plastic bit?

Also; Is there a way to proactivly reinforce the tops? I am more interest in the second question, as I was able to scrounge a replacement carb top for now. But if there is something I can do to prevent future issues, I'd be happier.

Thanks.
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Re: GL1000 carb top repair/reinforcement?

#2

Post by Toehead »

Funny you should say that! Somebody just posted a method a few topics down from yours, link here

http://www.ngwclub.com/forum/viewtopic.php?f=1&t=40216
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Re: GL1000 carb top repair/reinforcement?

#3

Post by Placerville »

For my own education/entertainment, I purchased a single carb. top just for the purpose of experimenting with what you've stated above i.e., reinforcement of the button. This all started when I saw a small crack developing on one of my carbs. buttons. I eventually remedied that by running a small bead of Cyanoacrylate glue along the crack. It was immediately absorbed, or pulled in, by the crack and I then clamped it. I polished it over and it was invisible and has held strong for two plus years.

So, regarding your question, I tried several methods and materials to 'reinforce' the button on the carb. top that I bought in a way that would not ruin its original look. Without going into all of them, this was the best for both strength and cosmetics:

Using a penny-sized amount of two-part 20 minute epoxy, I added a dab of white oil-based paint to the mixture (the amount that would cling to the point of a tooth pick). This small amount, included in the clear two-part epoxy, results in a cloudy-white translucent appearance very much like that of the original button. The amount that you put in can be adjusted until you get the color as close as possible to the original. Then, take a portion of the mixed epoxy, about the size of a pea, and place it on the top of the (cleaned) carb. button. Move the epoxy around on the top of the button with a toothpick until it is in full contact with every area including the metal edge. Then, slightly dampened your finger with paint thinner and carefully run it around the metal edge to create a clean fine line between it and the epoxy. This works very well when you take your time and practice. Next, turn the carb top over, and with the button facing down, momentarily apply a small amount of heat to the area with a hair dryer. The epoxy will soften, smooth over, and gravitate towards the top of the button. Rotate the cab in a 'button up / button down' rotation to control the flow and appearance. As the epoxy starts to harden you can slow the rotation. When the epoxy has cured, you'll have a very hard and smooth, translucent white covering over the button.

I found that the best part of using this method was, if you are not happy with the process, you can wipe the top clean with paint thinner and start over with no harmful results. The key things to watch for are: getting the color right and directing the flow towards the button top. 20 minute epoxy works the best as it shortens the 'rotation' time and, don't use too much epoxy. 'Less is more'.
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Re: GL1000 carb top repair/reinforcement?

#4

Post by Sidecar Bob »

I am not convinced that epoxy will be a permanent fix. 4 years ago we discussed methods of fixing the plastic buttons (doobies?) and the consensus was to epoxy something over them. Here's what I did http://www.ngwclub.com/forum/viewtopic. ... 333#p92333 (scroll down for a pic).

Within a month the washer/button joint let go on the #1 carb (the one with the broken button). I found it on top of the plenum so I cleaned it up and re-epoxied it. Last summer the washer/button joint on the #2 let go.The button on this carb is intact so I never got around to gluing it back on. Last weekend, while replacing the head gasket & head, I noticed that the nickle was missing from the #1 carb, as well as the piece that had broken out of the button (the epoxy fillet around the nickle was missing too). That explained why it had felt like it was struggling the day before. I found another nickle and this time I used J.B.Weld. This morning on the way to work the engine felt like it was struggling again so when I stopped for gas I looked and the nickle was missing again (this time the epoxy was still stuck to the washer). When I got to work I put a couple of layers of metal duct tape over it and it ran much better coming home.

It seems to me that the shafts of the slides occasionally hit the buttons and these impacts cause the epoxy to let go.

At this point, IMHO, the freeze plugs seem like the best solution, as long as the shafts of the slides don't actually hit them.
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Re: GL1000 carb top repair/reinforcement?

#5

Post by CYBORG »

wingovations sells a kit the replace the "buttons" works very well.....for a very long time
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Re: GL1000 carb top repair/reinforcement?

#6

Post by Sidecar Bob »

"Please be aware that these are NOT intended as replacements for the OEM white plastic buttons. They are intended as a cosmetic enhancement to hide the usually unsightly 30 year old originals.
Having said that, they have come in very useful when I have used them to cover up repairs to the OEM buttons done with epoxy resin." -WinGnovations website

I do not want to simply cover up an epoxy repair. I want a permanent fix that does not depend on glue.
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Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
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Another guy with two sidecars..... Hmmmm... must be something to that....
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Re: GL1000 carb top repair/reinforcement?

#7

Post by Whiskerfish »

""USUALLY"" these fail due to a bike that has issues and is running poorly and experiencing backfiring. I have actually seen them pop off when a bike backfires.
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Re: GL1000 carb top repair/reinforcement?

#8

Post by Old Fogey »

For some obscure reason, Keihin used the plastic button as the stop for the piston at full lift. If you get a violent lift as in a backfire, that's when you get the cracks in the top.
Some time back, I was looking at this problem and found that just a thin O ring or plastic washer pushed down over the guide pin would just prevent it from impacting the button. We are talking about something in the region of 0.5mm here.
But, I think that in the same circumstances it might just cause the main skirt to part from the guide pin, as the piston doesn't have much strength in that area. It can't really be strengthened as that would increase the weight, meaning using different spring strengths to get back to spec for lift.
So there is a choice: broken top or broken piston! Best solution in my view is the repair as previous post using the freeze/core plug but making sure that the guide pin CAN contact it at full lift.
Another solution that I have thought of but not got round to doing anything with, is to fix a stop ring inside the cap so that the skirt contacts it at the outer diameter. Something like a slice of correct sized plastic bottle glued in might do the trick.
Placerville's fix is good, but you are still in the position of maybe having it happen again since the cause has not been removed.
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Re: GL1000 carb top repair/reinforcement?

#9

Post by Sidecar Bob »

One other cause of failure of the buttons surely is old age. As I see it, when the plastic ages it becomes more brittle and it takes much less impact from the piston's shaft to break it.

GL1100 carb tops do not have the plastic buttons. What happens to them when the pistons over-travel?

CX/GL500/650 carbs are very similar and do not have buttons. Its 28c in the shade here right now and we are just in from a longish drive (I get magnifying glass fried ant syndrome if I sit inside a car for too long on a sunny day). Later on when it cools off a bit and I have had a nap I will bring my spare CX carbs down from the attic to have a look at their caps & pistons.

In the meantime, we picked up some freeze plugs today and posted on the other thread.
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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Re: GL1000 carb top repair/reinforcement?

#10

Post by Sidecar Bob »

The carbs without buttons have plastic bumpers inserted into the upper ends of the slide shafts. Unfortunately, they are not solddddd separately, even if they were the right size for the 1000. I will continue this in the other thread http://www.ngwclub.com/forum/viewtopic. ... 18#p432318
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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