Correct Carb Cleaning and Idle Jet/Circuit Cleaning

Correctly servicing the Carburettors on these bikes is paramount to good running and fuel economy so any work done will pay back in better mileage :)
Forum rules
To use Search function add Asterisks around the words like *fork oil*

No Racism.Slanging Matches(unless witty and funny :)
No spamming.Anonymous posting disabled.

Correct Carb Cleaning and Idle Jet/Circuit Cleaning

Postby LRCXed » Sun Jul 27, 2008 9:18 am

I'm going to start by telling you I just put a new oil & cam chain and mechanical seal in my motor and doing some maintenance after it sat for almost 3 years while I rebuilt my house from an electrical fire. I wanted to update the carbs to the style with the accelerator pump so I could eliminate the stumble on my 78 CX500 Standard during take off. (Later you’ll find out that had nothing to do with it) After 4 bad sets of carbs fished out of the Bay, I finally bought a good enough set to rebuild. I did the normal dismantlement and soaked them it the 5 gallons of Chem Dip carb cleaner, rinsed and sprayed them out with carb spray and 120 PSI air hose. I put the motor in and found the left cylinder was running lean at idle and low end. Even though I didn't even take it out on the road, I could tell. The pipe was starting to turn a deep gold in about an hour or more of tweaking with the motor and the carb synchronizing. The idle mixture screws did not act evenly when I started to adjust them. The right one almost turned in all the way and made the motor run better. It turns out though, that is probably because of the over filling float bowls, or so I though! I'll find out after they are installed and re started once again. I found a way to seal the needle and seat again like new!

One of the main problems with these old carbs, and I suspect many others, it that over the years of use, and lack of service, there are many areas where corrosion an calcium from water in the fuel tend to leave their deposits and clog passages and holes in emulsifying tubes, as well as air bleeds that control the level of fuel that is allowed to be pulled through the fuel jets and passages. Everything in a carburetor is designed to complement and control the next section of the system. If one is out of it designed specs, the next section suffers because of its short-sided ability to do its job adequately. We have all used carburetor sprays and dips to clean them with, and thought we were doing the best that could be done for them! Only to find out when we got it back together that not only didn’t they work right, but also there was something different happening now. Sound familiar?
I’m going to show you that there are many small passages that affect the performance of these fuel systems. Many of you will be able to relate to what I show you if you have ever had a set of carbs apart or have an old set sitting in the shed that you thought were junk. Use them to follow this tutorial.

The systems, believe it or not, that control EVERYTHING else in the carburetor, are the idle/low end and air bleed circuits. They affect even the main fuel feed for the high-end circuit.

Because of the need of an online acquaintance, Harold, I decided to explore the idle circuit on a set of carbs with stripped out threads and badly corroded bodies. These would be my sacrificial test beds. I was willing to cut them up if I needed to.

As you may know, there is an low/idle circuit jet embedded in the body of the carb under a rubber plug. Most that I know of, have never had one of these jets out, or been able to get out to service, or even know what it looks like inside! Under it was a world of surprises to me, as well as it will be to you!
As you will see, I found a way to remove the low/idle jet from the body to inspect and clean the idle system and it's passages. I found that because the idle jet is so high in the carb body, that any water that got into the system over the years, or even moisture in the air, tended to collect on the small holes in the low jets emulsifying tube and cause calcium to form and block the jets holes. I ripped apart 3 sets of carbs and they all had similar deposits plugging at least a few emulsifying holes and had deposits formed around the space between the jet and the body. That would explain why the idle circuits would not perform properly.

These next few pictures show the removal of the idle jet. I used a screw extractor made by Mac tools that I have had for years. I’m not sure if they still make it, but I’m sure they have them if not better quality than the one I have. I used the smallest size in the set. It was labeled size 1 or 5/64th.
I tapped it in with a small hammer to set it into the brass jet. It wont hurt it, or effect the jetting, because the actual jet size is drilled down inside the center of the jet, and there is a free space around the jet and the body so when the extractor is hammered in, it won’t get jammed in while it expands with the pressure.

Image

Now, with a small wrench of some type, I used a small crescent wrench or vice grips to turn the extractor in reverse, and PULL at the same time. It's important to turn it slowly. Don't twist it quickly. It will snap the extractor.

Image

It might help to heat up the aluminum of the body a little with a low flame torch, but I got all of the ones out this way in good condition. NOTE: Do not use CHEAP extractors, they will break and end up making the project as well as the carb, come to a screeching halt. As you can see, there is a shinny ring around the middle of the jet! This is the step where the jet presses into the carbs body. If you look closely, you will see that a hole above the open one is plugged with calcium.

Image

Because the clogs were from calcium, I went out and got some CLR! Calcium Lime Rust remover to see if it would eat away the deposits left by the water in the idle jets. One of the concerns was would it attack aluminum? Yes, it will, but not as fast as it attacks the calcium deposits. I placed these parts in a full strength solution of CLR, and it cleaned VERY quickly. The deposits were dissolved in about 10 to 15 minutes. While the CLR worked, I noticed that the end of a broken throttle shaft that I put in, the metal end, was bubbling, and the end of the idle adjusting screw that had the aluminum limiter was bubbling a little also. The aluminum throttle plate did not react. After rinsing with water, what you see is the end result. NO CALCIUM DEPOSITS!!!!!

First is the sacrifice of carb bodies and equipment used!

Image

These are the parts I soaked in CLR for about 10 to 15 minutes. All types of metals were represented here!
Notice the CALCIUM build up of white on the idle jet!

Image

This shows the start of the chemical cleaning reaction on the metal end and the aluminum in the CLR!

Image

Now you will see there is no more calcium deposit after the CLR soaking, and it did not eat any of the aluminum since I only dipped it for a short time.

Image

After cleaning, I found each orifice size in each hole of the different emulsion tubes and jets.
LOW JET/emulsion tube holes.
Image
LOW JET center fuel metering hole.
Image
SECONDARY EMULSION TUBE (main jet)
Image
PRIMARY EMULSION TUBE (under secondary jet)
Image
This is the air cutoff passage port going in under the idle jet. Make sure its clear! Most are though.
Image

Each air or fuel orifice was checked with a very accurate precision micro jet drill index to ensure the holes were clean and set to their proper size. I did this by starting with smaller than accurate sizes of each hole, and could feel the gummy or crusty build up inside each one. When I got to the right size jet drill, I could no longer feel the smoothness of the build up in the passage, and I knew I was at the right size for each orifice. None of the holes were drilled larger.
I used a small drill jet drill index to size each hole in every jet or emulsion tube! You can see the set in the picture of the idle jet and the drill going into the side holes!

NEW ADDITION;
In the original post I forgot to add this!
Included it the idle circuit cleaning, there is 3 holes inside by the throttle plate. ALL are directly connected and are ALL a part of the idle circuit. The holes in mine were plugged in various degrees. In order to be able to clean and knock loose the deposits in and under them, I used a welding tip cleaner. It's soft metal and was easy to bend and get in the holes. When you open the throttle plate, you will see 2 more. Clean them out as well, and then spray carb cleaner through them from the same side you entered the tip cleaner. This will spray the dirt and deposits out through the larger holes in the circuit. Blast every thing each way, and all ways possible before you blow it out with the high pressure air blower. This is my worst possible goof up in this post. It is so important to clean these out. These are the idle and off idle system holes that effect the throttle just as you start to add the gas. When these are plugged the transition of the throttle could be a little uneven. Sorry I missed it guys, but it's here now

Image


Now it's time to reset the idle jet back into the body! I use a VERY thin coat of lock tight to ensure it's sealed and tight just at the base where the jet presses into the body! Where the shiny ring is! Don't use so much that it will drain down into the holes and plug them up again. Tap it in securely so it sets tight! Use a brass punch, not metal. It could flatten the end of the jet!

Image

These are the air jets in the top of the body under the piston. I found a couple of these were really gummed up, even after I soaked and cleaned them with carb cleaner and blew them out with 120 PSI air hose. It took the jet drills to clean them out thoroughly. And then sprayed them out with the carb cleaner again and blew them out with the air hose.
These are the air bleeds that I mentioned above, that effect the entire fuel circuit and its performance.

Image

I went to a jewelry supply store and got a rubberized fine polishing bullet shaped polisher that had the angled tip to clean the seat for the needle and seat assembly. I put it on my reverse easy out and twisted it about 4 times while pressing in on the seat to clean and polish it. It cleans and polishes the seal very nicely now with no old build up to get in the way to make it leak. The narrow one under it is a brass wire brush that I used to clean out the entire seat assembly. I got that at the jewelry store also.

Image


Image

Just so you can see and understand what is under the seat for the needle and seat assembly, I pulled one out. There is a large area and a tapered step under the seat. It can collect a lot of debris in there, so you need to do all you can to flush it out and loosen all the deposits possible before assembling the carbs. If you thing you have done enough, do it some more! You can't get this area to clean. When the vibrations of a running motor start to loosen up the deposits, they can flow in and under the jets. Clean them some more!

Image
NOTE: DO NOT PULL OUT THE FUEL NEEDLE SEAT. THESE PICTURES ARE FOR VISUAL BENEFIT ONLY.
Notice the step around the seat! This is where the junk collects and settles.
Image

After all this cleaning and re cleaning, these carbs should perform like new.
Make sure that after all the drilling and cleaning you spray the carbs out well. There will be a lot of deposits that you are going to be knocking loose and will need to get out of there. If you can, use a high-pressure air hose and a good quality carb spray that does not evaporate quickly, it will eat more out the longer it stays moist.

In the last few years, things have changed in my process of cleaning carburetors. I now use an ultra sonic cleaner with a mix of simple green and water. 4 to 1 mix. Without a doubt there is NO better way to get them cleaned. It cleans out passages inside the carbs that you could never do by hand or with sprays. It is absolutely the best and most thorough way to get your carbs cleaned.

When I was done with the set for my 78 CX500, I no longer had an idle issue, and all the adjustments in the idle circuit worked evenly on each side. Even the discoloration on the exhaust headers stopped changing, and has stayed the bright chrome finish since I have done this procedure.

The responsiveness of the motor has improved drastically, and it seams that my gas mileage has improved as well. I will post those results when I get a better record of what it has done.

If you are not confident that you can perform this procedure, or do not have the equipment to do so, E-mail me if you would like your carburetors done. I would be happy to service them for you!

Good luck, and enjoy the results! Its well worth the time and effort, to rid your self of those gremlins that have been haunting you for so long.
Larry
Last edited by LRCXed on Thu Jul 31, 2008 1:51 am, edited 5 times in total.
"If I need to have someone do something for me, why shouldn't I learn to do it myself"
User avatar
LRCXed
 
Posts: 183
Joined: Thu Jul 24, 2008 11:33 pm
Location: Sacramento California

Re: Carb Idle Jets Cleaning

Postby Blindstitch2002 » Mon Jul 28, 2008 5:06 am

I was just thinking about this post over at the other site. The real question is after you get done cleaning them can you resist polishing them?
1979 Honda Cx500 Custom Supertanker
User avatar
Blindstitch2002
 
Posts: 191
Joined: Fri Jul 25, 2008 12:49 am
Location: Greenfield, Wisconsin

Re: Carb Idle Jets Cleaning

Postby LRCXed » Mon Jul 28, 2008 5:49 am

Hmmmm...as a matter of fact.....NOPE 8-)

Image

How could I Don, its like the mountain climber, "its just there" :P
"If I need to have someone do something for me, why shouldn't I learn to do it myself"
User avatar
LRCXed
 
Posts: 183
Joined: Thu Jul 24, 2008 11:33 pm
Location: Sacramento California

Re: Carb Idle Jets Cleaning

Postby Blindstitch2002 » Mon Jul 28, 2008 6:27 am

Hey those look nice. Closest I got to polishing mine was when I went to the car wash today one of the dials said polish. I admit that I tried it but they still look the same. Took the oil residue and dirt off the transmission cover though.
1979 Honda Cx500 Custom Supertanker
User avatar
Blindstitch2002
 
Posts: 191
Joined: Fri Jul 25, 2008 12:49 am
Location: Greenfield, Wisconsin

Re: Carb Idle Jets Cleaning

Postby LRCXed » Mon Jul 28, 2008 6:33 am

:D :mrgreen: :) ;) LOL. I wish it were that easy!
"If I need to have someone do something for me, why shouldn't I learn to do it myself"
User avatar
LRCXed
 
Posts: 183
Joined: Thu Jul 24, 2008 11:33 pm
Location: Sacramento California

Re: Carb Idle Jets Cleaning

Postby connella08 » Mon Jul 28, 2008 8:27 am

i have a spare set that i have been talking to larry about via email where i had tried to take out the slow idler jet (emulsion tube) with a easy out screw extractor and the tip broke off inside of it. well i decided that my running pair need to be reworked after learning about how so little dirt can cause major running issues. instead of using a new easy out to get the emulsion tube out, i took a screw about the size of the hole in the top of the emulsion tube (not a wood screw, more like a tiny bolt with a philips head on it) and made it self thread into the top of the jet. when i got it in a few turns, it was short enought to get my pliers under the head horizontally and pried up like i was using a crowbar. popped right out and it was real solid too. i didnt think it was going to break at all. i'll take some pictures of it later and post them up. honestly, i think this screw idea might be better if tried first. if it fails, then go to the extractor.
connella08
 
Posts: 5
Joined: Fri Jul 25, 2008 1:02 am

Re: Carb Idle Jets Cleaning

Postby LRCXed » Tue Jul 29, 2008 5:56 am

Good one Connella, that was going to be my second attempted in the beginning when I started the project. But the first one worked, so I forgot about trying it. Good job! Next time, before you put the screw in, put a washer and a nut on it so when its set, you can tighten the nut to pop the jet out like we take the fans off a motor using a bolt!. A little heat would help too. I think it would save the chance or damaging the tube stacks aluminum housing, unless you put something between the pliers and the body! Then I guess that would help protect it. Don't forget to blast the 3 idle holes out through the idle jet screw hole also. They get plugged up too. Check the reference above for cleaning sizes.
I JUST CHECKED ABOVE AND SAW THAT I FORGOT TO ADD THAT PART! I WILL GO DO IT
It's done!
Let us know how it makes out.
"If I need to have someone do something for me, why shouldn't I learn to do it myself"
User avatar
LRCXed
 
Posts: 183
Joined: Thu Jul 24, 2008 11:33 pm
Location: Sacramento California

Re: Carb Idle Jets Cleaning "W/ added info update"

Postby connella08 » Wed Jul 30, 2008 9:18 pm

SUCCESS! after disassembling my carbs and soaking them in vinegar (cleans them out and highly recommended) i sprayed them out and threw them back together. i had a small leak but i think it was an o-ring in the t-pipe for the fuel that fixed itself. it started up and ran nice and smooth. after a little riding i let it cool off and started it back up the next day, but it wouldnt rev well, even when warm. i was told by lrcxed to re-sync the carbs and after about a half an hour of tweaking, ITS NEVER RUN BETTER! it actually goes when i tell it to and it pulls, HARD!

i definitely recommend doing this procedure (but dont skip steps or rush, you will pay in the end if you do.
connella08
 
Posts: 5
Joined: Fri Jul 25, 2008 1:02 am

Re: Carb Idle Jets Cleaning "W/ added info update"

Postby Randall-in-Mpls » Wed Jul 30, 2008 9:55 pm

LRCXed wrote:PRIMARY EMULSION TUBE (main jet)
Image
SECONDARY EMULSION JET (under secondary let)
Image

Larry,

I think you have the primary and secondary reversed here. It's the Secondary Main Jet that's metered by the vacuum piston needle.

R
1978 CX500 - Black Grub
User avatar
Randall-in-Mpls
 
Posts: 27
Joined: Mon Jul 28, 2008 11:07 pm
Location: Minneapolis, MN

Re: Carb Idle Jets Cleaning "W/ added info update"

Postby LRCXed » Thu Jul 31, 2008 1:13 am

So it is Randall! That will teach me to work till 2:30 am trying to finish a post. :oops: And being on pain killers for my shoulder at the same time! Not a good match! Thank you so much. This is the second goof that has been found. I'll go fix it!

Larry
"If I need to have someone do something for me, why shouldn't I learn to do it myself"
User avatar
LRCXed
 
Posts: 183
Joined: Thu Jul 24, 2008 11:33 pm
Location: Sacramento California

Next

Return to CV(Constant Velocity) Carbs

Who is online

Users browsing this forum: No registered users and 1 guest

Help keep this forum ad-free - please Donate


This free, ad-free forum is hosted by ForumLaunch
cron