Topic: Leaky Carb Question

[aaguilar3]

Hello,

After doing my research on leaking carbs, I've found out it can be a couple reasons. The main one being the needles and seat might be bad and not closing the fuel off properly. The second main one I've heard is float level is wrong. Is there a way to test the valves and seat? I did check my float levels and 1st was 24mm the rest were about 23mm. I believe the 73' cb350f is supposed to be at 26mm. You guys can correct me if I'm wrong. I know I need to adjust those also. But I don't want to just adjust and them put them back on the bike just to find out it didn't solve the issue. Any help would be appreciated greatly.

[aaguilar3]

From more research I did I found I could also connect the carb to the fuel with the float bowl open and manually close the valve to see if it stops fuel. Intstead of making a mess this way can is there any other suggestions to test the needle and seat? Or is this my best bet?

[flybox1]

350F floats should be near 24mm, IMO.  This can, and should be confirmed with the clear tube test.

From more research I did I found I could also connect the carb to the fuel with the float bowl open and manually close the valve to see if it stops fuel. Intstead of making a mess this way can is there any other suggestions to test the needle and seat? Or is this my best bet?

This is best.  Do it off the bike, for safety reasons, and the ease at which things can be adjusted.  An aux tank is not that difficult to mock up for $5....or just put your tank above your workstation.

[aaguilar3]

Ok so if it's 24mm they really don't need an adjustment then and the culprit is more likely the float needles and or seats. I guess I will have to test them one by one. Thanks for your help again!

350F floats should be near 24mm, IMO.  This can, and should be confirmed with the clear tube test.

From more research I did I found I could also connect the carb to the fuel with the float bowl open and manually close the valve to see if it stops fuel. Intstead of making a mess this way can is there any other suggestions to test the needle and seat? Or is this my best bet?

This is best.  Do it off the bike, for safety reasons, and the ease at which things can be adjusted.  An aux tank is not that difficult to mock up for $5....or just put your tank above your workstation.

[Bodi]

The Honda service manual says 21mm, via measurement of the float when the tang just touches the valve. Measuring the actual fuel height with a tube will give a different measurement, the floats do sink a bit in the fuel.

[aaguilar3]

Update: I ordered new float needles and seats. I installed them and flipped the carbs as they would be on the bike in my hand and then flipped them back. Some of the needles are sticking in the seat and not allowing the float to come back down to close position. Can someone help me with this? Does this have to do with the tang catching the top of the needle? It takes a bit of pressure to set them back into place. I believe this is what was causing and still causing my overflow issues. I did test the floats with gas and holding them with my fingers closed and no gas is leaking. So the issue is the floats getting hung up.

[aaguilar3]

I checked and I did find that the needles are indeed getting caught up on the float tangs. This is partly because I had the height set at 21 and also because of the way they were bent uneven. I sanded the surface that touches the needle tip and also adjusted the height to 23 and it seems to have cured the catching. They now are seating properly.

[aaguilar3]

I also tested to make sure the floats float and the overflow tubes were not cracked. On another note my petcock is letting fuel through on off. Is this because the bowl o ring is bad?

[BobR]

  Most likely the rubber piece pictured with 4 holes isnt sealing. It may be in need of replacing. That said if the washers on the screws that attach it to the tank dont seal it will allow gas to get by also- but slowly.
  I replaced mine but also had to flat sand the lever to get it to work properly. Bob

[aaguilar3]

I actually did use that kit within the last week. Only thing I didn't replace was the washers for the screws. I also had an extra flat small o ring that I didn't see in any diagram of where it could go

  Most likely the rubber piece pictured with 4 holes isnt sealing. It may be in need of replacing. That said if the washers on the screws that attach it to the tank dont seal it will allow gas to get by also- but slowly.
  I replaced mine but also had to flat sand the lever to get it to work properly. Bob

[aaguilar3]

In your pic it's the one below the 4 hole one

  Most likely the rubber piece pictured with 4 holes isnt sealing. It may be in need of replacing. That said if the washers on the screws that attach it to the tank dont seal it will allow gas to get by also- but slowly.
  I replaced mine but also had to flat sand the lever to get it to work properly. Bob

[BobR]

 I believe its for different models where they attach. Anyhow initially I had issues with mine after rebuilding it. I lightly flat sanded the sealing surface of the lever, then smoothed it with scotchbrite. Considering it looked fine before I did so I am not sure why but it worked. Bob

[aaguilar3]

Hmmm. I can try that.

I believe its for different models where they attach. Anyhow initially I had issues with mine after rebuilding it. I lightly flat sanded the sealing surface of the lever, then smoothed it with scotchbrite. Considering it looked fine before I did so I am not sure why but it worked. Bob

[Robbo]

Did you reinstall the wiggly washer that puts pressure on the fuel tap lever so it doesn’t leak?  There should be two screws, a cover plate, then the wiggly pressure washer, then the fuel tap lever which sits against the 4-hole fuel tap seal.


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[aaguilar3]

I did. Might try setting it in a different position or something. I went through it again and replaced the washers for the screws that bold to the tank. Checked the 4 hole one to make sure it looked good. Reset everything and it still is allowing little dribbles of fuel to come out the spout in off. Would the culprit most likely be the 4 hole ring? Or the squiggly washer ring being worn out?

Did you reinstall the wiggly washer that puts pressure on the fuel tap lever so it doesn’t leak?  There should be two screws, a cover plate, then the wiggly pressure washer, then the fuel tap lever which sits against the 4-hole fuel tap seal.


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[BobR]

I did. Might try setting it in a different position or something. I went through it again and replaced the washers for the screws that bold to the tank. Checked the 4 hole one to make sure it looked good. Reset everything and it still is allowing little dribbles of fuel to come out the spout in off. Would the culprit most likely be the 4 hole ring? Or the squiggly washer ring being worn out?

Did you reinstall the wiggly washer that puts pressure on the fuel tap lever so it doesn’t leak?  There should be two screws, a cover plate, then the wiggly pressure washer, then the fuel tap lever which sits against the 4-hole fuel tap seal.


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 Its possible- there may not be enough pressure from the old spring washer. That said my issues happened even with a new one.    As for the washers I ended up using the old fiber ones. At any rate a leak there would be very slow imo.

[aaguilar3]

I should be able to get a wavy washer from Lowe's right or is this a specialty item?

I did. Might try setting it in a different position or something. I went through it again and replaced the washers for the screws that bold to the tank. Checked the 4 hole one to make sure it looked good. Reset everything and it still is allowing little dribbles of fuel to come out the spout in off. Would the culprit most likely be the 4 hole ring? Or the squiggly washer ring being worn out?

Did you reinstall the wiggly washer that puts pressure on the fuel tap lever so it doesn’t leak?  There should be two screws, a cover plate, then the wiggly pressure washer, then the fuel tap lever which sits against the 4-hole fuel tap seal.


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 Its possible- there may not be enough pressure from the old spring washer. That said my issues happened even with a new one.    As for the washers I ended up using the old fiber ones. At any rate a leak there would be very slow imo.

[Robbo]

Where did you purchase the rebuild kit?


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[BobR]

I should be able to get a wavy washer from Lowe's right or is this a specialty item?

I did. Might try setting it in a different position or something. I went through it again and replaced the washers for the screws that bold to the tank. Checked the 4 hole one to make sure it looked good. Reset everything and it still is allowing little dribbles of fuel to come out the spout in off. Would the culprit most likely be the 4 hole ring? Or the squiggly washer ring being worn out?

Did you reinstall the wiggly washer that puts pressure on the fuel tap lever so it doesn’t leak?  There should be two screws, a cover plate, then the wiggly pressure washer, then the fuel tap lever which sits against the 4-hole fuel tap seal.


Sent from my iPhone using Tapatalk

 Its possible- there may not be enough pressure from the old spring washer. That said my issues happened even with a new one.    As for the washers I ended up using the old fiber ones. At any rate a leak there would be very slow imo.

 Genuine OEM right here -$4. Its a specialty item Lowes wouldnt have -at least I dont think. Bob

http://4into1.com/genuine-honda-petcock-spring-16960-268-010-cb160-72-77-350f-500k-750k/

[aaguilar3]

4into1

Where did you purchase the rebuild kit?


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[aaguilar3]

Thanks, going to check OSH first just in case.

I should be able to get a wavy washer from Lowe's right or is this a specialty item?

I did. Might try setting it in a different position or something. I went through it again and replaced the washers for the screws that bold to the tank. Checked the 4 hole one to make sure it looked good. Reset everything and it still is allowing little dribbles of fuel to come out the spout in off. Would the culprit most likely be the 4 hole ring? Or the squiggly washer ring being worn out?

Did you reinstall the wiggly washer that puts pressure on the fuel tap lever so it doesn’t leak?  There should be two screws, a cover plate, then the wiggly pressure washer, then the fuel tap lever which sits against the 4-hole fuel tap seal.


Sent from my iPhone using Tapatalk

 Its possible- there may not be enough pressure from the old spring washer. That said my issues happened even with a new one.    As for the washers I ended up using the old fiber ones. At any rate a leak there would be very slow imo.

 Genuine OEM right here -$4. Its a specialty item Lowes wouldnt have -at least I dont think. Bob

http://4into1.com/genuine-honda-petcock-spring-16960-268-010-cb160-72-77-350f-500k-750k/

[aaguilar3]

Does the positioning of the spring (wavy washer) make a difference?

[aaguilar3]

Just ordered a new one. Tried it a couple different ways and still leaks.

[Robbo]

It shouldn’t make a difference.

I just rebuilt my petcock/fuel tap with a kit from 4 into 1.

I did not replace the 4 holed seal (my issue was that reserve position wasn’t working.

I could have replaced it but when I compared the seal to the oem, the oem part looked slightly larger.

I am wondering if you go and get an oem one if your problem will be fixed.

If you take it apart again, please take close up photos of the 4-hole gasket fitted in the petcock, and the inside flat face of the fuel knob that sits against that gasket.


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[aaguilar3]

Got the OEM spring and it still leaks. I'm assuming this is now the 4 hole gaskets fault?

It shouldn’t make a difference.

I just rebuilt my petcock/fuel tap with a kit from 4 into 1.

I did not replace the 4 holed seal (my issue was that reserve position wasn’t working.

I could have replaced it but when I compared the seal to the oem, the oem part looked slightly larger.

I am wondering if you go and get an oem one if your problem will be fixed.

If you take it apart again, please take close up photos of the 4-hole gasket fitted in the petcock, and the inside flat face of the fuel knob that sits against that gasket.


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