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Discussion Starter #1
I posted this on the America forum, but thought I'd run it by you guys as well. 2008 Carb 865 America.

I had the carbs off my America for a re-jet following airbox mod.
It ran great for a couple miles then... bogs to a halt like tank is empty. It isn't, has several gallons. And it's a new tank so rust is not an issue. It ran great before the mod.

My suspicion (and hopes for an easy fix) is this:
There are two cross over tubes between the carbs. The black one on top has a "T" midway between the carbs. The lower metal one has the "T" close to the LH carb near the idle speed adjuster.
Question is this:Which crossover is for the fuel supply from petcock and which is the overflow/vent? I think I may have reconnected them backward. The shop manual's diagram is nondescript.

I did not mess with the floats other than R&R to check the needle valves. They were OK. I'm certain that I didn't bend the little tang.
The carbs were balanced after the jet swap and spark plugs cleaned and gapped.

The LH header pipe was discolored a good bit after my ride, obviously very lean. Neither spark plug showed evidence of lean condition, but I only rode about 5 miles before trouble showed.
When the bike stalled out on the ride, it restarted and ran poorly after sitting for a while, only to stall again in 1/2 mile or so. So getting some gas, but not enough. (just running off gas in float bowls and refilling too slowly??)

SO... could someone with a carbed model please look to see which crossover the hose from petcock should lead to?
 

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As no pros have responded you'l have to settle for my $0.02 worth. The rear most and lower offset T fitting is for the hose from the tank, the higher one toward the front for the vent, but I don't think that's your problem. There is or should be a filter/strainer inside the hose from the petcock just above the ''T''. Turn off the petcock, unplug the hose from the ''T'' while holding a container under the hose open the petcock and see how the fuel is flowing. If low flow remove the hose and blow back through the hose from the filter end to see if crud comes out the top end. Remove the filter and make sure it's clean. Before replacing the filter check the fuel flow without it to make sure the strainer in the tank isn't blocked. Also open the gas cap and blow back through the tank vent hose from the bottom to make sure the vent is open... Good luck
 

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As no pros have responded you'l have to settle for my $0.02 worth. The rear most and lower offset T fitting is for the hose from the tank, the higher one toward the front for the vent, but I don't think that's your problem. There is or should be a filter/strainer inside the hose from the petcock just above the ''T''. Turn off the petcock, unplug the hose from the ''T'' while holding a container under the hose open the petcock and see how the fuel is flowing. If low flow remove the hose and blow back through the hose from the filter end to see if crud comes out the top end. Remove the filter and make sure it's clean. Before replacing the filter check the fuel flow without it to make sure the strainer in the tank isn't blocked. Also open the gas cap and blow back through the tank vent hose from the bottom to make sure the vent is open... Good luck
Just to add as a non-pro to Mr. Rweb's comments. "lower offset T fitting is for the hose from the tank"
I believe that is actually a vent line going back and down the mid-frame and out the left side.
If indeed we are talking about the same "line" that vent has to be vented to atmosphere and will do through the carbs fuel balance off and have the same effect you described.

Maybe something to look into. :smile2:
 

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Discussion Starter #6 (Edited)
RATS!! It was connected correctly, so there's another problem.

Thanks for the pic BonnieBlack, but you didn't have to remove your carbs just for me!!
 

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That vent line we have pointed out, thanks to the nice picture Mr. BonnieBlack posted has to be free flowing to atmosphere.
Any obstruction will cause the carb float levels to rise and give you the condition you described. Runs great for a short while then stalls out like you ran out of gas.
It goes behind the carbs down and out the left side. There is a factory clip to hold it and that can cause the line to collapse.
 

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Discussion Starter #9 (Edited)
Problem solved

All the mentions of a blocked vent made sense. Turns out that the tip over valve was remounted too close to horizontal and blocking the tank from venting!
Thanks to all for your suggestions.

BTW , the bike runs beautifully using Dinqua's calculator.
TORs, UNI filter, cut out airbox baffle (airbox bottom not drilled), snorkel removed, 1,000-2,000 ft. MSL.
stock needles, no shims, 130 main jets, 45 pilot jets
 

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