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Hello,
I cleaned carbs CX500 Eurosport PC06 (should be the same as GL500), and I found out interesting problem.
The original assembly should have two fuel joint pipes (see the photo).
Slide3.JPG

I was surprised that the secound pipe was completely missing. The holes were pretty covered by dust, so i think the previous owner hadn't the secound pipe for a longer time.
Ok than, let's try to find where to get secound pipe, but there is something more interesting: one carb has the hole, the secound hasn't:

Slide1.JPG Slide2.JPG

This is a visible difference between the first and secound pipe, the first pipe has both holes in carbs clearly visible.
You can see in the photo that instead of hole there is small dimple - it remind me making a dimple before drilling. I am sure it is blind dimple about 0.5 mm deep, no hole full of some deposit.

What do you think, please: is it realy fake, the hole must be here as it is in other carb?
Is it possible that during the producing 30 years ago the driller broke and the hole was not finished?
Can someone explain me, what is the secound fuel pipe for? I thing the previous carbs for CX500 had only one fuel pipe.
Do you have some scheme, cross-section where is visible where the hole goes ?

Thank you for any advise,

Jan from Prague
 

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Hi there, the second pipe is for the accelerator pump and yes there should be a hole there to allow fuel from the accelerator pump to reach the other carb. Very odd that the hole isn't there. How was the bike running with these carbs on?
 

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Discussion Starter #6
Thank you all, guys...
carbs should be the same as for GL500, than yes, two pipes...CX500 not Euro version should have one only.
Acceleration pump? Is there really? Is possible that this only preparation if someone wants to use it, but original is without?
No, I don't think previous owner changed them, and no idea how carbs run before - I bought it from Germany as not running, stored for a few years

But I have new interesting remark:
I fill the hole for the secound fuel pipe by denatured alcohol (because of low viscosity) in order to find where the channel goes.
Nowhere, it is blind! I even closed the hole and shaked with it, no lackage. Then I put a needle inside, it is about 15mm long hole without any edges inside, I could not find any connection to the other channel inside...
This is strange, what is it for?
Is really possible it just a preparation?

Thank you, Jan
 

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Hi there, the second pipe is for the accelerator pump and yes there should be a hole there to allow fuel from the accelerator pump to reach the other carb. Very odd that the hole isn't there. How was the bike running with these carbs on?
Eurosport models in some countrys did not have accelerator pumps. Larry Cargill documented the set off my 650 that doesn't have it and there have been other members reporting this as well. It looks like mainly North American models had them. Do not be alarmed that yours do not have the holes and tubes as the Gl500 carbs. The jets may be slightly different sizes compared the the Gl500 carbs.
 

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Eurosport models in some countrys did not have accelerator pumps. Larry Cargill documented the set off my 650 that doesn't have it and there have been other members reporting this as well. It looks like mainly North American models had them. Do not be alarmed that yours do not have the holes and tubes as the Gl500 carbs. The jets may be slightly different sizes compared the the Gl500 carbs.
Wouldnt that "open hole" on the one carb suck air?
 

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Jan, don't be concerned about not having the accelerator pump/tube. As Holyman said, overseas countries didn't require the pump to get the carbs to work properly. We got them in our bikes because the government required the bikes to run leaner and pass certain emission standards. So they added the pump to make them respond better off the line. Look inside the air inlet side of your carbs and you'll see there's no brass pump nozzles. That is a clear indication that the cross pipe holes were not drilled.

This is a picture of Holyman's 650 carbs. you'll notice the brass nozzles are missing as well as the pump tube.





If you had the accelerator pump, you would see the nozzles in the inlet side.

 

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Discussion Starter #10 (Edited)
Jan, don't be concerned about not having the accelerator pump/tube. As Holyman said, overseas countries didn't require the pump to get the carbs to work properly. We got them in our bikes because the government required the bikes to run leaner and pass certain emission standards. So they added the pump to make them respond better off the line. Look inside the air inlet side of your carbs and you'll see there's no brass pump nozzles. That is a clear indication that the cross pipe holes were not drilled.

This is a picture of Holyman's 650 carbs. you'll notice the brass nozzles are missing as well as the pump tube.





If you had the accelerator pump, you would see the nozzles in the inlet side.


Thank you LRCXed and others, you make me relaxed...
There are indeed no nozzles in inlet, so this is the explanation.
So all is fine, great! :)
I understand that probably the body is the same regardless of variant - with or without accleration pump. Just a bit surprising that one side has a blind hole, secound even blind. But ok, no problem for this variant.


Please last question: Holyman, how did you clean your carbs in so perfect shine surface?
I used firstly ultrasound cleaner, some polishing paste for metals, even some amateur advises such as coca-cola or lemon juice, but i couldn't manage it so shiny...
 

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It's sickening how polished those carbs are lol! But then again if mine were that nice looking they wouldn't match the rest of my bike lol!!
 
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The cleaning and polishing you see we're done by Larry who posted the photos. And yes they are better looking than the rest of the bike now.
 
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