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Discussion Starter · #1 · (Edited)
The trials and tribulations of a 30-year old carb

First off thank you very much to everyone who post here, there is a wealth of knowledge on this site. That being said, maybe someone can help me here. Im in the process of rebuilding and cleaning my carbs on my 81 cx500c when these two "adjustment" screws SNAP completely off. Auto part Automotive wheel system Tire Wheel Automotive tire
:mad::mad::mad::eek::eek::eek: Would anyone possible know where I could order some of these?
 

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these two "adjustment" screws SNAP completely off. Would anyone possible know where I could order some of these?
Yep. The heads snap off those mixture screws far too often. It's not, in my opinion, a very good design to have that wasp waist in screws with such a large head.

The screws are part of the carb rebuilding kits. I have always bought mine from eBay sellers. Some sellers offer the screws alone as well.

http://www.ebay.com/itm/Keihin-Air-...Parts_Accessories&hash=item2a3c392a7e&vxp=mtr

Your favorite bike parts dealer can fix you up as well.

How did the screws snap? This is important. If they were bumped and snapped as you were trying to straighten them, that's one thing. If the screw is stuck tight with corrosion and snapped under heavy torque, that's something different. Either way, you need to drill the screws an use an easy out.

Accurate center punching is the first step. If your mark isn't as well centered as you would like, you can punch the hole again, at an angle, to get it better centered.

If you have a drill press, use it. It can certainly be done with a hand drill, but why give half your attention to keeping the drill straight? Use a sharp drill bit and a drop of oil.

You don't want to drill completely through. About 0.2" deep should be enough to get an easy out in there. Tap it in lightly with a mallet and back the screw out.

If it snapped off because it was stuck, it's still going to be stuck. The easy out's grip on the screw is no stronger than the original screw. You'll need to soak it with PB Blaster for as much as several days to give yourself every advantage. When a simple soaking is not enough, I've had success with temperature cycling. First in the oven (80C) and then in the freezer.

Don't overpower it and strip or break off the easy out.
 

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Discussion Starter · #5 ·
Wow, thanks for all the help guys, that was fast. I've followed the "researched" methods of cleaning these carbs, but even after soaking them in CLR, they still have a sort of "chalky" feeling to them. Has anyone ever used Goo-Gone to remove any remaining build-up? I need to scrub the heck out of them, this is a picture of them after soaking in CLR and rinsing/scrubbing. Auto part Machine tool Metal
 

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. . . they still have a sort of "chalky" feeling to them. Has anyone ever used Goo-Gone to remove any remaining build-up? I need to scrub the heck out of them . . .
I've never been satisfied with any chemical cleaner when it comes to exposed surfaces. I like to polish mine with Scotch Brite, sometimes dipped in a borax/water slurry. A toothbrush reaches some of the nooks and crannies. For harder to reach areas, a small patch of Scotch Brite with tweezers.

I notice some sparkling slides in the photo. When you cleaned them, did a lot of black smutz come off? Slides are often lubed with graphite. You might want to spray them with a fresh layer before reassembly.
 

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Discussion Starter · #7 ·
Also I found that a Safety pin does seem to go deep enough in the circuit to clean it. Approximately how deep is this circuit? Auto part Carburetor Automotive engine part
 

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clr is a bad thing to soak them in it actually promotes electrolysis transfer of metal

the chalky feeling is broken down dissolved metal the metal the carb bodies are made of has a lower sacrificial potential of all the reat of the carb parts
 

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Discussion Starter · #10 · (Edited)
Guess what I found for FREE, an ultra sonic cleaner!
It's little but i can fit the biggest components into it.. Anyone in this area in need of an ultra sonic cleaner can use it! Im hoping this can clean it out well enough.

Still trying to get these damn idle jets out tho.... Auto part Small appliance Metal
 

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Discussion Starter · #11 · (Edited)
black water DONT do that!!

the pin you are using is enlarging the hole and may damage the idle jet tapered seat

and in the case of what you are doing you can pass a small clean out wire right out the adjustment jet hole
I didnt force it into there. Just barely moved it around.
And the CLR I only let soak for 15 minutes.. I THOUGHT that would be ok.... : /

Edit, murrayf, I used to live in Currituck County, Nc. Moyock to be precise. Isnt it NICE down there?!?
 

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Also I found that a Safety pin does seem to go deep enough in the circuit to clean it. Approximately how deep is this circuit?
You might want to take it easy with the safety pin. A lot of rebuilders consider that a big no-no. The hard steel against soft aluminum can easily alter the characteristics of that jet. Not that people don't do it all the time with good results, but you never know if you've introduced some subtle change.

Just from memory, those holes are through only a ~ .050" thick wall before they open up into a drilled-out passage. Inspect it visually to identify the other end of each passage. Squirt some carb cleaner through each one to assure it's open. Blocked ones can sometimes be cleared with compressed air. Otherwise, soaking and an ultrasonic cleaner.
 

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Discussion Starter · #13 ·
I've never been satisfied with any chemical cleaner when it comes to exposed surfaces. I like to polish mine with Scotch Brite, sometimes dipped in a borax/water slurry. A toothbrush reaches some of the nooks and crannies. For harder to reach areas, a small patch of Scotch Brite with tweezers.

I notice some sparkling slides in the photo. When you cleaned them, did a lot of black smutz come off? Slides are often lubed with graphite. You might want to spray them with a fresh layer before reassembly.
Yea it was kinda blackish.

As for the safety pin, Im sure I didnt damage anything as I only "set" it in there to take the picture.
 

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Discussion Starter · #14 · (Edited)
After running just one side of the carb submerged in the sonic cleaner the water was BROWN. Will have to clean them multiple times per side. It looks like someone rubbed a hot tootsie roll around on my carb... :sulkiness:
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After running just one side of the carb submerged in the sonic cleaner the water was BROWN.
Great! So you know it's working. Just think where that stuff might have ended up if you hadn't done it.

Did you use straight tap water? Or did you add something to help loosen the crud?
 

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Discussion Starter · #16 · (Edited)
I seem to be having VERY good results with Non-concentrated Dawn dish soap. Im using filtered water out of water bottles.
I've got the sonic cleaner going constantly. In betwwen cleaning im soaking the carbs in very hot tap water.
Rinse cycle repeat a million times to be sure.
Still have to get the idle jet out.. Dont have an EZ-out that small...

Also, See the broken spring below? Wonder if it had anything to do with the throttle problems I was having....
I have not cleaned this carb yet.
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Discussion Starter · #18 ·
That is the choke return spring
Ah, was definately having problems with my choke not staying out. You guys are awesome!
 

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Without that spring the right side choke won't close. It's not a return spring as such but makes the chokes close and open together.

Keep ultrasonicing the end of the carb with the broken off mixture screw, it will make it easier to remove by removing the crud that is locking it in place.
 

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Discussion Starter · #20 ·
Without that spring the right side choke won't close. It's not a return spring as such but makes the chokes close and open together.

Keep ultrasonicing the end of the carb with the broken off mixture screw, it will make it easier to remove by removing the crud that is locking it in place.
That spring was basically detrimental in the correct operation of the choke. Without it, the left side choke was staying closed. But, I managed to fix the spring and actually make it better than it was stock. I put these carbs back in today and couldnt believe it, the bike fired RIGHT up and idled amazingly.

I owe absolutely every bit of it to this forum. Thank you guys very much for all of the help! Now it is my turn to return the favors! :cool: :blob8:
 
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