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1986/xx? XV1100 Help with my carburetor [SOLVED]

Have a question about fixing something on a Yamaha Virago XV1100? Post it here!

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hyllus
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Joined: Wed May 22, 2019 10:14 am
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1986/xx? XV1100 Help with my carburetor [SOLVED]

Post by hyllus » Sat Sep 21, 2019 5:57 pm

This has been a long battle to get a 1986 that was given to me back on the road. I have replaced everything I know of on the carburetor and put a new fuel pump in. When I start it, fuel is flowing out of the outlet shown in the diagram attached. Can someone tell me what this outlet is and why fuel would be coming out of it?
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ViragoJoe
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What Virago you Own: 1996 Virago Special XV1100SH
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Re: 1986/xx? XV1100 Help with my carburetor

Post by ViragoJoe » Sun Sep 22, 2019 10:01 am

hyllus wrote:
Sat Sep 21, 2019 5:57 pm
This has been a long battle to get a 1986 that was given to me back on the road. I have replaced everything I know of on the carburetor and put a new fuel pump in. When I start it, fuel is flowing out of the outlet shown in the diagram attached. Can someone tell me what this outlet is and why fuel would be coming out of it?
hyllus,

That outlet on the Carburetor Is a diaphragm vent (one for each Carburetor), those tubes just connect to the back side of the stock Chrome Pod(s) via hoses. These tubes can not be blocked off, they require clam air for the diaphragms (slides) inside the carbs to work properly. The main reason the hoses are just set inside the pod(s), for support and "Calm Air". You don't want them flopping around in the breeze (not a good idea) with varying air pressures.

Virago Hitachi Carbs:
https://www.viragohelp.com/virago-hitachi-carburetors/

This Excerpt below was taken from the above link regarding Hitachi Carbs:

Quote
Note on venting tubes: Those venting tubes coming out of the carbs near the top are important. They provide air to the main and pilot air jets, and maintain open air pressure throughout the carb body (except above the diaphragm). These tubes have little filter pods on them which contain two screens with a thin layer of foam sandwiched in between them. In many of them by now that foam has turned to dust. When you pull off your diaphragms and slides upon disassembly, look for dirt/dust coming in from those tubes. If there is some, you may want to deal with those filters, that is, provide the venting system with some fresh foam (UNI has some). I’ll leave the details of this project up to you. Otherwise, just blow the filters out well with air and keep going. The main requirement is that they breath freely and are not shedding particles into your carbs..

The other important point about vent tubes is that they need to exit into quiet air to where wind and other sudden changes in air pressure don’t find their way in to the air jets. Older Viragos provide for this with outlets behind the left side cover, and newer ones with outlets in the pods.
Unquote

Not sure, what year bike you have now.
Back on August 5th, it was a 1987 XV1100. Not that it matters, here. But, better to be consistent on year and model.

If you would have specified the bike as an 1988 XV1100, things would change, carbs would now be Mikuni different from Hitachi. Correct years and models are important, when trying to resolve issues! Things can change a great deal from model year to model year!

This topic below of yours from August 5th, still holds true today.

1987 XV1100 Leaking fuel
viewtopic.php?t=1025

You never replied to your August posting, if what was provided you worked or not, apparently, it didn't. Float levels are usually the culprits here for any gasoline leaking from anywhere on the Carburetor.

Also, see this posting by Dr. Frankenstein (a.k.a. John). This too, may resolve your problem.
A little long on reading, but well worth it to see the outcome!!
viewtopic.php?f=40&t=993

Let us know, if this fixes your problem.
ViragoJoe
1996 XV1100SH Virago Special
"Never ride faster than your Guardian Angel can fly!!"
;)

hyllus
Posts: 6
Joined: Wed May 22, 2019 10:14 am
What Virago you Own:

Re: 1986/xx? XV1100 Help with my carburetor

Post by hyllus » Mon Sep 23, 2019 9:06 pm

Thank you! It's taken me a few days to go through all the info you sent and I'm still not through it all but it is extremely helpful. The posting by Dr. Frankenstein was especially helpful because it sounds like the exact same issue I'm experiencing. Sorry for the confusion - the beast I'm trying to fix is a 1986 XV1100 with the Hitachi twin carbs. From everything I've read so far, my problem is either a. sticking needle valve, or b. incorrect float levels. Like Dr. Frankenstein, I've meticulously set the float levels, checked the needle valves, etc. The only thing left to do is take his approach and try to just set the float levels "as needed". I'll let you know how it works out.

hyllus
Posts: 6
Joined: Wed May 22, 2019 10:14 am
What Virago you Own:

Re: 1986/xx? XV1100 Help with my carburetor

Post by hyllus » Tue Oct 08, 2019 8:26 pm

Finally got it running! I learned a lot while trying to get this bike back on the road. I thought I’d share some of the things that became obvious to me a long the way. I’m sure most of these things are common knowledge on this forum, but I had to learn them the hard way.
• Test the carbs off the bike. I was getting pretty frustrated making what I thought were the perfect float level adjustments then putting the carbs back on the bike only to find them leaking. I finally got wise and built a little harness on my bench clamp to hold the carb at the right angle. I hooked up some tubing to the intake and injected gas into the bowls using a big syringe. When it would leak, I’d take the bowl off, adjust the float height, put it back together and fill them up again. I repeated the cycle until it stopped leaking. I hooked another piece of hose to the outlet and checked the fuel level.
• Float heights are not the same. I had the impression the floats for both carbs should be the same height. Turns out, using the process above, one float needed to be a full 2 mm lower than the other one to keep both bowls at the right fuel level.
• Slight float adjustments mean a lot. I bought a float height gauge to make the float adjustments. There was only a millimeter’s difference between the carb flooding and not.
• Floats can stick. Because of the angled shape to the bowl, it seemed like sometimes the floats would wedge against the walls of the bowl when empty. This gave me the false impression that the level wasn’t correct when it would leak. When I finally figured out what was happening, I gave the bowl a gentle tap and they filled up correctly.
Thank you all on this forum that helped me.

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