Author Topic: ‘71 Honda cb500- first time attempt of carburetor removal/cleaning (Read 11023 times)

vulture0027@gmail.com · « **Reply #50 on:** March 16, 2019, 11:29:21 PM »

Hit the pilot system air jet with carb cleaner

vulture0027@gmail.com · « **Reply #51 on:** March 16, 2019, 11:44:30 PM »

Removed and cleaned needle jets aka emulsion tubes and made sure that all of the tiny holes were clear (pic #1)

To do this, I had to lift the gas slides (aka throttle valve?) by turning the “big idle adjuster” (pic #2)

To get the needle jets out I had to use a toothpick press down on the needle jets from the top to loosen them, then take the wooden pick and wiggle the needle jets out from the bottom (pic #3)

vulture0027@gmail.com · « **Reply #52 on:** March 16, 2019, 11:58:44 PM »

I checked the floats and made sure that they can move up and down freely and that the swivel pin was clean... I did NOT use anything abrasive on these (or ANYTHING THAT I CLEANED......just carb cleaner and, at times, a soft pipe cleaner)...(pic #1)
Made sure the the o rings on the main jet no. 100 were intact/not cracked/etc. I had to replace some of these.
FYI I did NOT attempt to adjust the height of the floats

vulture0027@gmail.com · « **Reply #53 on:** March 17, 2019, 12:07:26 AM »

In addition....

I sprayed carb cleaner through the orifices of where the main jets (pic 1)

Checked for cracks in the brass overflow tubes by filling up the float bowls with gas using the set up that I have pictured in pic 2.... just used a Tupperware container and suspended the float bowls one by one with bbq skewers and looked for leaks

vulture0027@gmail.com · « **Reply #54 on:** March 17, 2019, 12:11:00 AM »

I feel like I’m forgetting something here... but pretty much any thing I unscrewed I blasted it with carb cleaner .... lemme know if I left anything out

vulture0027@gmail.com · « **Reply #55 on:** March 17, 2019, 12:16:31 AM »

Oh, and I got rid of the inline fuel filters and ran the fuel lines straight from the gas tank to the carbs.
30cm for the long gas line and 18cm for the short one

vulture0027@gmail.com · « **Reply #56 on:** March 17, 2019, 12:32:53 AM »

Slapped the carbs back in.

Started the bike.... ran like hot garbage.

Headers one and two were hot... 3 and four were ice cold.

Knocked (gently) on the float bowls. Opened up the drain screws... no gas.

Turned the petcock back and fourth.... knocked on the carb bowls again

Opened up float bowls of 3 and 4 again...

Gas drained from 4, but not from 3...

I figured I’d try to give the bike a start anyways (to see if by some “act of god” that good ol carb 3 would fall in line... bike wouldn’t respond by me turning the key... no lights on the “control panel”...

I’ve had the bike on the trickle charger for about three hours, and still lights don’t come on... I don’t THINK I jostled any of the electrical components whilst doing any of this.... how long does a battery need to charge in order for the bike to register that it has charge?

Deltarider · « **Reply #57 on:** March 17, 2019, 01:23:12 AM »

1. Disconnect the fuelline that feeds carb 3 and 4 from the petcock and check there's sufficient flow coming from the petcock's corresponding brass tube.
2. Is there sufficient gas in the tank? Are you on reserve? If so, add fuel to the tank. Realise that the column height is very modest and that it takes very little to hinder gravity in doing its job forcing fuel to the carbs.
2. Have you routed the fuelline to 3 and 4 correctly? If you use the clamp on the carbsplate (center front) for it, it almost guarantees it will run as it should, without going up and down. When in doubt, post a pic.
3. After you have verified the tube is routed correctly, you may gently blow some air through the tube to 3+4. This might free a sticking float needle in #3. Gently!
About the electricity.
Could it, you have left something ON?
Inspect the fuse first. If fuse is OK, switch the IGN key a couple of times.
How old is the battery? Do you have a multimeter to read Volts?

vulture0027@gmail.com · « **Reply #58 on:** March 17, 2019, 04:35:36 PM »

- definitely getting sufficient flow from the petcock.
- I filled the tank a week ago
- not in the “reserve”
- I THINK I have the lines routed correctly... still getting gas from float bowl #4.
- I’m not sure what you mean by “clamp/carb plate”

Deltarider · « **Reply #59 on:** March 18, 2019, 01:51:25 AM »

Quote from: vulture0027@gmail.com on March 17, 2019, 04:35:36 PM

- definitely getting sufficient flow from the petcock.
- I filled the tank a week ago
- not in the “reserve”
- I THINK I have the lines routed correctly... still getting gas from float bowl #4.
- I’m not sure what you mean by “clamp/carb plate”

It's on the front of the frame (in Hondaspeak: PLATE SET, STAY) that holds the 4 carbs. To be honest, the clamp is not that essential. It's not much of a clamp either. It's more a wrap of tin or aluminium that can be bent easily. I've run my bike for years before I even noticed it was there. I'll see if I can make a pic. If the tube is the right size and if you have used the special hole in the carbframe to route the tube towards the T-joint (3+4), there's not much chance you could have routed it wrongly. BTW, you don't need the little clamps where the tube connects to the T-joints; there's no way they can come of. If you have gas arriving in #4 carb's bowl, but not in #3's, it indicates there's either the #3 valve needle sticking or there's a blockage. A sticking needle can be helped by tapping that carb or blowing some air (gently) through the fuelline. Have you verified before reassembling, the needle could smoothly move up and down in the valve and that the float could swivel likewise? When there's still dirt somewhere in the route to #3, it would mean you have not verified well enough the route is free and open prior to reassemby. Another thing: verify the brass tube under the #3 carbbowl and its rubber tube are open, so the carb can vent. Easily checked by blowing some air. If those are blocked, it could hinder fuel supply. Another but unlikely cause is that the tankcap does not vent enough. Easily checked by just opening the cap and see if it makes a difference.

vulture0027@gmail.com · « **Reply #60 on:** March 18, 2019, 05:51:42 PM »

Yeah, I blew air through the overflow tube, through the gas lines, tapped on the carb with a screwdriver... still no gas.
I see what you were talking about (as far as that “clamp” goes). But yeah, gas lines look like they’re running through correctly.
I forgot to open on gas tank to see if that was the problem....I’ll do that when I get home tonight.

***before reassembly I checked to make sure that all of floats were able to swing freely... I THOUGHT I checked to see if the needles dropped drop down with gravity... but maybe I didn’t check as well as I thought. I DID NOT run any fluid through the carbs to make sure that gas would reach each carb bowl before reassembly... so yeaaaaah.
When I get home I’ll check to see if the gas tank trick works.... if not, looks like I’ll be taking the carbs out for the third time.

I had a dream the other night that I was working on the carbs and all the sudden they collapsed in my hands like a house of cards that had been knocked down.... I’ll have to ask my therapist what that means

vulture0027@gmail.com · « **Reply #61 on:** March 19, 2019, 03:21:33 AM »

Deltarider- I don’t know.... I pulled the carbs out again and everything looks good. The valve seat and needle moved fine.

Actually, when I removed the carbs from the bike, quite a bit of gas spilled (I’m guessing because I couldn’t drain the float bowl from #2 (because the drain screw was stripped)...

I’m not sure if the excess gas from #2 leaked into the #3 float bowl, BUT THERE WAS Reminants of gas in #3.... any thoughts?

vulture0027@gmail.com · « **Reply #62 on:** March 19, 2019, 03:30:10 AM »

Lastly, I took the needle out of the valve seat and sprayed the #$%* out of the port that that the needle was sitting in with some carb cleaner.....

There was a little resistance, then the carb cleaner seemed to flow through the opposite end (fluid came out of the gas line)

Deltarider · « **Reply #63 on:** March 19, 2019, 06:25:27 AM »

That 'There was a little resistance' could indicate there's still something in there that hinders free flow. If the floatneedle is taken out, you can blow air from the valve up and then full force. WD-40 is fine to clean the valve and needle tip as it is at least a little lubricous which might help prevent the needle from sticking in the valve.
That clamp, CLIP, TUBE in Hondaspeak, is shown as part #11 in the pic. The pic is a bit misleading however, the tubeclip is located in front of the carbs actually. The clip is not essential provided you have the fuelline in correct length. I did years without. One could say that it helps to keep the tube a bit further away from the hot engine in front of it.

vulture0027@gmail.com · « **Reply #64 on:** March 21, 2019, 01:51:54 AM »

Well , after all of your guy’s instructions.... my girl is running great!! I can’t thank you guys enough... especially deltarider....

You guys have saved me money... and most importantly, I got to know my bike....

THANK THANK THANK YOU!!!!!!!!!

mattsz · « **Reply #65 on:** March 21, 2019, 02:01:23 AM »

You'll be helping others, too! This is the first place I've found details of which carb ports go where, to know when cleaning is working. Not sure if '71 CB500 carbs are identical to '77 CB400 carbs, but they sure look similar. I'll be referencing this thread when I get around to cleaning my carbs later this spring... thanks guys!

Deltarider · « **Reply #66 on:** March 21, 2019, 12:55:21 PM »

Thank you Vulture for the wonderful photos. You made a great tutorial. Do add some fuel system cleaner the next two tankstops. If possible, ride it often. Nine out of ten issues I had with my CB500 had to do with sitting.

Charles T · « **Reply #67 on:** March 22, 2019, 08:11:13 PM »

Be extremely focused, careful, methodical and surgically clean. Buy reputable carb kits x4. Carefully clean outside of carbs. Carefully follow the manual. One carb at a time. Don't be in a hurry. Have good lighting. Have clean containers for all those tiny parts. Clean tidy newspaper covered bench to clean parts on. Careful with compressed air, little parts can fly for miles. Clean newspaper covered bench for cleaned parts, put into clean sealed containers. Judicious use of an ultrasonic cleaner is recommended by a lot of people. Make sure all holes and galleries are clear. Use the correct options out of the kits. You may need a magnifying light to read jet sizes and positioning of needle clip in middle groove. Use lightest smear of silicon grease for o rings. Be very careful with the tab washers and spring loaded anti backlash springs in the linkage mechanisms. All of this is very time consuming, but essential. Its worked for me and now I'm at the tuning stage.
Charles T

Genniker · « **Reply #68 on:** May 25, 2019, 01:57:10 PM »

Hi,

This is a fantastically informative thread, especially so looking to piggyback the thread as I've just embarked on the same exercise to clean the carbs.

I've cleaned all the bottom end float chamber areas and jets, and now looking to drive the emulsifier tube out from the top to give them a clean. But seem to be stuck on what to do next as the throttle yoke doesn't want to turn, so to enable me to lift the throttle arms. I see in the thread that it might be stiff, but won't move for me. It worked fine when connected to the handlebar throttle.

I've seen the youTube tutorials and they seem to turn the yoke with one hand. Is there something I haven't disconnected?

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Author Topic: ‘71 Honda cb500- first time attempt of carburetor removal/cleaning (Read 11023 times)