Rebuilt VHB 29 Carbs don't run real well

[scottmastrocinque]

Brass bristle brush is ok but gentle contact. Don’t press hard.

 

[Former User robertx901]

Hey guys, should I take the accelerator pump piston apart (I do hear the little ball rattling inside when I shake it)?
*Does the 10mm nut at the top screw out from the main body? Seems pretty tight.
*Should I be able to see through the assembly? I see no daylight when I look through.....
Thanks!

 

[scottmastrocinque]

How about a “How to…” guide!

Copy and paste this into your browser window.

thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

This should get you all the way home.

 

[Former User robertx901]

Thanks, I'll do that!

 

[scottmastrocinque]

Thanks, I'll do that!

You are welcome.

Funny thing is I believe that Amboman, here on this site, is in fact Charlie Mullendore of Antietam Classic Cycle, who Greg mentions in the text.

I’m surprised he didn’t chime in but nevertheless, I’m glad I was able to relocate that from the back of my mind to share with you and others who might need it.

 

[Amboman]

You are welcome.

Funny thing is I believe that Amboman, here on this site, is in fact Charlie Mullendore of Antietam Classic Cycle, who Greg mentions in the text.

I’m surprised he didn’t chime in but nevertheless, I’m glad I was able to relocate that from the back of my mind to share with you and others who might need it.

Yes, one and the same. I haven't chimed in more, because every time I scroll up to look at the previous posts, my PC screen goes dark, a little box appears telling me that my graphics driver has stopped working and has recovered (a lie), then I have to completely reboot to get it to work again. No issue anywhere else on this forum, or anywhere else on the 'web. Weird.

 

[Former User robertx901]

Yes, Charlie is a great resource!
I'm going back through both carbs now, will do a better job this time around. I'll let you guys know how it goes when I've reinstalled them.
I am still curious about the SS1 carbs. I took them off becuase of reviews that said they might leak and start a hot engine on fire. I do think I solved the leaking problem on mine and I'm always wondering if I, at some point, might want to put them back on. The bike (and SS1s) have about 8,500 miles. Anybody have an opinion about them?

 

[Amboman]

Yes, Charlie is a great resource!
I'm going back through both carbs now, will do a better job this time around. I'll let you guys know how it goes when I've reinstalled them.
I am still curious about the SS1 carbs. I took them off becuase of reviews that said they might leak and start a hot engine on fire. I do think I solved the leaking problem on mine and I'm always wondering if I, at some point, might want to put them back on. The bike (and SS1s) have about 8,500 miles. Anybody have an opinion about them?

My friend Larry replaced his v700's SS1s with VHB 30s from an 850-T3. No jetting changes to the VHBs. Gas mileage went from the low 30s to the upper 40s, and throttle response was greatly improved. Even if SS1s don't leak, they rarely meter properly in my experience.

 

[Former User robertx901]

Thanks Charlie.

 

[Former User robertx901]

Update: I finally had time to go through the carbs again -- found two clogged jets which I replaced. When I attempt to start it up now all I get is a click -- no doubt the starter solenoid or starter motor (probably starter motor). I'm going to run some tests on both and, if I have a question, will post it on a new thread. Thanks again for all your help, I appreciate it!

 

[john zibell]

If it is the starter, any auto electric shop can rebuild it. But first make sure the battery is good. As we say the only way to tell for sure is a load test that can be done an any auto parts store. After you check the battery or before, remove the starter and see if it will spin with no load.

 

[SirKeppa]

Hello everyone. Right now I am dealing with the exact same problem that the topic here describes and I am looking for some help/advices.
I rebuilt my VHB 29 of my 1972 Eldorado and now the machine wont start or if it starts it runs like a can full of screws and will die immediatly as soon as I touch the gas throttle.
The carbs are fitted with all new jets but everything is factory size-whise. I think one major problem/mistake I have is that I swapped the original mixture screws with after market ones. Unfortunatelly the old ones are gone so I cant swap them back. These after market ones have a slightly but visibly shorter tip and it seems I just cant get the mixture near to anything startable.
This are the basic dimensions in millimeters (sorry!).


I assume that the basic configuration setting wont work with that right? Do you have any suggestion how to start?
Additional things that are different after rebuilding the carbs is that I used two instead of one sealing between the float bowl and the float bowl cap unterneath the carb. So the cap will be a tick deeper but should that make any difference function-whise?????
I also swapped the idle screws with newer ones but that seems to work fine. Idle and mixture screws are installed without any rubber seal or washers...only the screws and the flattened springs.

Thank you in advance guys...

 

[john zibell]

You need to have the washer and o-ring on the shaft of the idle mix screw. Turn them in until fully seated, that back out 2.5 turns as a start point. Also you should only need one o-ring on the float bowl. Also check that the enriching jet plungers are sealing as it should.

 

[SirKeppa]

You need to have the washer and o-ring on the shaft of the idle mix screw.

Thank you. So do I need the o-ring and washer even if these were not installed originally with the factory style mixture screw? They are required now because of the shorter tip?

 

[john zibell]

Thank you. So do I need the o-ring and washer even if these were not installed originally with the factory style mixture screw? They are required now because of the shorter tip?

Did you see the last page of the PDF? The shorter screw does use the washer and o-ring.

 

[SirKeppa]

Yes John I saw it but I thought that is only one possible setup. So it's a complete setup with the short screw. Thank you very much, I will try that asap!

 

[Amboman]

VHB 29s and 30s as used on the Loopframe and Tonti Guzzis do not use an o-ring and backer washer - just the screw and the spring.

 

[SirKeppa]

VHB 29s and 30s as used on the Loopframe and Tonti Guzzis do not use an o-ring and backer washer - just the screw and the spring.

Yes ... thats what I thought at first. I am not sure if it will work If I add the o-ring/washer. That screw I posted is sold for VHB carbs but in reality it comes from the PHB series. It seems there is no 1:1 repop screw for VHB on the market... unfortunate for me now. PHBs are using the screw with ring and washer but I assume the inner contours of a VHB are different...
I mean I can give it a try but not sure if the carbs will run better or worse...

 

[Amboman]

Yes ... thats what I thought at first. I am not sure if it will work If I add the o-ring/washer. That screw I posted is sold for VHB carbs but in reality it comes from the PHB series. It seems there is no 1:1 repop screw for VHB on the market... unfortunate for me now. PHBs are using the screw with ring and washer but I assume the inner contours of a VHB are different...
I mean I can give it a try but not sure if the carbs will run better or worse...

That is the correct screw. The same screw is used on PHF, PHM, PHBH, PHBE/PHB and PHBL carburetors.

 

[SirKeppa]

Hi Amboman.. i am by far no expert with carbs. I understand how they work and thats it. By saying this is the correct srew you mean it is a working replacement screw right?
I am asking because the original mixture screw looks slightly different from that newer one WE are talking about. It basically has a shorter nose tip as the original screw that can be found in a untouched VHB-29.

Left is the new one and on the right the factory one.

Now my question is if that contour change effects the air adjustment? If you guys say it should work fine with that different nose tip i have to look further why my Eldorado wont run now.

I am a bit confused because i get messages from "it wont run with that screw" to "wont make any difference"


Thanks!