The long road to carb cleaning

[akinz]

So after all of 3 years of the CBX sitting and I don't know how many more years before that, I'm finally getting to go through the carbs for my 79.

I've been able to do a lot of things with ease thanks to all of you, pulling the pilot jet was probably the biggest. The other being a cracked standpipe, which I never could see until when I bench tested the carbs, saw that there was one that appeared the float valve was leaking, instead it was the cracked pipe.

I found out later on through reading last night that although I blew air through the pipe, I never put my finger over the end. To all that are going to take on carb cleaning or rebuilding, it would be beneficial to do this test while you have the bowls off. I noticed mine from bubbles coming out of the crack after petrol had been in the bowl already, but brake cleaner would do the same thing.



After I soldered the one, I found another crack on the same pipe, so cleaned and soldered that one up too.


All in all things are going good, but I have a couple questions still..
When I squirt cleaner through the pilot jet, should I be seeing the fluid coming out of the three air bleeds infront of the throttle plate? Seems as though I only see fluid coming out of the mixture opening.





Thanks in advance guys, man I can't wait to fire this thing up!!!

[whatscooking]

For a quick answer try blocking with your finger the front hole, its got to come out of all those holes. I am a rookie here but there is no reason to put one back together until you get all of the passages flowing. As I recall when I pulled the idle jets you can see into the bottom of the hole there are two small holes, one is for the air coming in to mix with the fuel and the other one heads up to those holes you show. You have got to get your spray tube into that hole to get a good flow going to those holes in the carb throat. Lota holes here, the pages in Mikes book that I have are the most worn that show where everything is connected.

[akinz]

Thanks whatscooking. Ya I ended up disassembling the carb bodies again because I wanted to make sure, sprayed through the pilot jet while stopping up the idle screw mixture opening and out blasted cleaner through all 4 of all 6 carbs so back together with new rubber bits!!!!

Did a bench sync, which glad I did, the one bank of 3 was completely out of sync compared to the other. Wet tested and all seems good now!

Now to put these babies back to their rightful home!! Hopefully I can hear some notes this afternoon!

[akinz]

So after all of 3 years of the CBX sitting and I don't know how many more years before that, I'm finally getting to go through the carbs for my 79.

I've been able to do a lot of things with ease thanks to all of you, pulling the pilot jet was probably the biggest. The other being a cracked standpipe, which I never could see until when I bench tested the carbs, saw that there was one that appeared the float valve was leaking, instead it was the cracked pipe.

I found out later on through reading last night that although I blew air through the pipe, I never put my finger over the end. To all that are going to take on carb cleaning or rebuilding, it would be beneficial to do this test while you have the bowls off. I noticed mine from bubbles coming out of the crack after petrol had been in the bowl already, but brake cleaner would do the same thing.



After I soldered the one, I found another crack on the same pipe, so cleaned and soldered that one up too.


All in all things are going good, but I have a couple questions still..
When I squirt cleaner through the pilot jet, should I be seeing the fluid coming out of the three air bleeds infront of the throttle plate? Seems as though I only see fluid coming out of the mixture opening.





Thanks in advance guys, man I can't wait to fire this thing up!!!

I hope maybe Dave could chime in here.

I was hoping to get my CBX on the road this week after rebuilding all the brakes, master cylinders etc, new brake pads, new fork seals, rebuilt rotor, rebuilt the carbs and cleaned them....

By the fall last year I got the bike fired up finally, but it still wasn't running right. Seemed to idle fine, but as I have read here it running on 5 cylinders might sound fine to someone who has never owned one of these beauties, which I am in that class.

I took the carbs off the bike this past weekend and stripped them down of their bits, removed the slow jets as well since this is easily done now from the last time I extracted them. Sprayed everything noted in Nixon's carb book. I am going to take them off once again because it doesn't really clearly state it in the book...

My question... the 3 small air bleeds by the throttle plate... are those ALL for the idle circuit? When I spray from the top of the carb in the idle circuit (under the slide) and in the air cut off valve opening, I get good fluid coming out of the slow jet, primary main, idle mixture screw opening, idle mixture hole in the throat where the throttle plate is and what seems like a dribble out of the closest air bleeds to the pilot hole. Should it be spraying out of that one air bleed? Or all 3 clusters? Can someone explain to me what those other holes are for? My understanding is one is for the idle circuit, one for primary main, and one for secondary main?

When the bike is idling and I give it some choke, I can definitely tell it's running perfectly. Same when taking off from a stop, if I give it a little choke, it takes off completely fine. Otherwise it will bog and stall out if I don't rev it up some to get it going.

I have done the header heat test by hand and they all seem similar to me. Seems as though whichever carbs it is, fires some times....

To me the choke is a dead give away that it's the carbs and the idle circuit.

I'm so so close.....

[daves79x]

To test those 3 holes, you need to do 2 things: Block off the Primary main tower with a screw threaded into it 1/2 inch or so. This prevents your test fluid (brake cleaner) from bleeding right over into the idle jet tower (they are connected if you look at the towers). Then take a bare pilot screw and thread it into it's tower under the carb throat until it seats. You should see a bit of the brass tip sticking up into the throat. Now blow carb cleaner into the idle jet tower (jet can be pressed in or just the bare hole). You should now see a strong spray coming out of the 3 holes by the throttle plate. That's the only way I know to block off all the other possible exits for the brake cleaner and channel them to the 3 holes. There will still be a small path to the air cut-off circuit, but it's too small to affect the spray much. Follow with high-pressure air through the idle jet.

I do this with every carb in every set I rebuild. Then check that all the air bleeds are open in the top of the carb body. Wet test the carbs for leaks, and just as importantly, for accelerator pump operation. Do not re-install the carbs until you've proven that all 6 accelerator pump nozzles squirt strongly. Blow high pressure air into the feed hole in #3 body (bowl off) to clear any clogged ones. Follow with brake cleaner and more air.

Dave

[akinz]

To test those 3 holes, you need to do 2 things: Block off the Primary main tower with a screw threaded into it 1/2 inch or so. This prevents your test fluid (brake cleaner) from bleeding right over into the idle jet tower (they are connected if you look at the towers). Then take a bare pilot screw and thread it into it's tower under the carb throat until it seats. You should see a bit of the brass tip sticking up into the throat. Now blow carb cleaner into the idle jet tower (jet can be pressed in or just the bare hole). You should now see a strong spray coming out of the 3 holes by the throttle plate. That's the only way I know to block off all the other possible exits for the brake cleaner and channel them to the 3 holes. There will still be a small path to the air cut-off circuit, but it's too small to affect the spray much. Follow with high-pressure air through the idle jet.

I do this with every carb in every set I rebuild. Then check that all the air bleeds are open in the top of the carb body. Wet test the carbs for leaks, and just as importantly, for accelerator pump operation. Do not re-install the carbs until you've proven that all 6 accelerator pump nozzles squirt strongly. Blow high pressure air into the feed hole in #3 body (bowl off) to clear any clogged ones. Follow with brake cleaner and more air.

Dave

Ok, so I should be seeing fluid spray out of all 3 bypass holes by just spraying in the idle jet? That has to be why it idles and takes off much better with the choke!

Thank you very much Dave. I'll be sure to write back with my findings!
Kyle

[herdygerdy]

May be a little too late, but this may help....

Fixing cracked float bowl tubes on CBX carbs

http://cx500forum.com/forum/general-dis ... ement.html

Also thanks for the tips on clearing & checking the idle jet circuits Dave. Always good to learn new improved ways of doing this...

[akinz]

May be a little too late, but this may help....

Fixing cracked float bowl tubes on CBX carbs

http://cx500forum.com/forum/general-dis ... ement.html

Also thanks for the tips on clearing & checking the idle jet circuits Dave. Always good to learn new improved ways of doing this...

Thanks Herdy,

Yes, I came across how to fix the overflow pipes a bit ago. I think when I originally posted. I haven't taken the carbs off the bike yet, but I guarantee since fluid is supposed to come out of those 3 little bleed holes from spraying in the slow jet, that is 99 % my problem. I'll make sure to write up after I do this again.

Dave, any rememberance of what the size of the machine screw you used for the primary main block off?
Thanks again,
Kyle

[daves79x]

5mm I think. Not a common size on a CBX, but pull one of the 2 mounting screws for the fuse cover on the forks - it'll fit perfectly.

Dave

[akinz]

5mm I think. Not a common size on a CBX, but pull one of the 2 mounting screws for the fuse cover on the forks - it'll fit perfectly.

Dave

Great thank you so much!