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2006 Honda Shadow Spirit VT750DC
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Discussion Starter · #1 ·
06 spirit 750.

When I tore my carb apart last week, I had a hose that seemingly came from nowhere. No clamps or clamp marks on the hose. I pretty much thought it was useless, but I think I found where it goes. I am just asking to make sure.

On each carb there is a small port near where the choke screws in. What is this port for? I believe my mystery hose connects both of these ports together based on the various pictures I took during removal, but like I said I want to double check before I do anything. The curvature of the hose also leads me to believe it goes here.

I never paid attention to it because all the instructions I followed mentioned nothing about this.

A few pictures of the hose and port.
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Discussion Starter · #3 ·
I'll try that tomorrow, but that's what I'm starting to think. The first picture I took of the carb on my bench, I can see the hose in question just hanging there and as far as I know I never touched it.

A lot of videos I am looking at don't even have a hose anywhere near there also lol.
 

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Discussion Starter · #5 ·
Trust me, anything I physically disconnect or remove gets a picture taken. That's why I have no idea about this because I don't believe I even touched the hose during disassembly.


Edit: And yes the hose in the first picture is the one in question. Once I got the carb out and on the bench I took a picture and the hose was just hanging there. I'll find and post that picture here in a second.
 

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Discussion Starter · #6 ·
This picture is literally carburetor out of the bike, put on the bench and a picture taken. I believe the mystery hose is on the LH side between the choke cable and under the throttle cable wheel.


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Discussion Starter · #8 ·
I will double check tomorrow. Didn't get to the bike today cuz it was pretty humid and crappy to be hanging out in a garage for a while.

I do believe the hose in the back of the air cleaner box (the one that has hoses going to the carbs) is where it is supposed to be. I know for a fact that hose either was disconnected already, or became disconnected when I started everything because I took a picture of it. I also have not reinstalled any of the air cleaner stuff because I cleaned them yesterday and had to apply some sealant to part of it.

I do appreciate the suggestions though. I will go over the steps I followed and see if I missed anything.
 

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Discussion Starter · #11 ·
It's not the tank vent I know I hooked that up lol.

I plan on taking the carb back off tomorrow anyways, but I will take pictures again with carb removed and post. Maybe that might help.
 

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Discussion Starter · #12 ·
I pulled the carbs to double check a few things, and I connected the hose between the two ports near where my choke cable threads in. I hooked the hose up to each port and blew into them, and they were open, so I figured why not. I had also seen a TJ brutal customs video where he was talking about removing the EVAP system and had plugs on what looked like these ports. They go to the throttle plate, which I will include a picture of.

I was able to get the bike started much easier, still with choke, and eventually have it running with the choke off. Then I could start it with no choke, so I am heavily leaning towards these ports needing the hose or plugged for whatever reason. I cannot find anything that really says what they are, but I am guessing with them not plugged, more air is getting into the carb which isn't supposed to be.

Here is a picture of the ports in question, and the hole the air was coming out of. I appreciate everyone's input! Thank you!

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Discussion Starter · #20 ·
Good call gentlemen!

Here's a write-up of somebody who wanted to remove the CA emissions stuff from their '98 750 ACE. California Emissions Removal – VT750DC.com There's a little discussion and some diagrams there. Honda calls the vacuum hose that powers the valve, #10, and it doesn't show if it is sourced from one carb or teed to both. My first instinct would be that crossing over the intake ends of the carbs of dual carbs would be a bad thing. Only one carb is sucking at a time, wouldn't mixture be motivated to go first one way, then the other through a crossover hose?

Unfortunately the image at the link that shows which ports the author capped is missing.

My VLX 600 is a CA bike, and I think that there is a fault in the vent emissions collection system that is causing the bike to run rich, but I'll investigate that further when I get some spare time to pull the tank and fool with it. I can look at how my 600 is plumbed at that time.
Third or fourth picture down, the ports in question are pointed out and it says to cap them. The picture is clear as day. Makes me wonder if this hose was originally there or not still. I think I like the idea of not having them connected as mentioned in an above post. I received some caps in my rebuild kit. I will remove the hose and put caps on tomorrow and see what that does. Excellent link, thank you!
 

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Discussion Starter · #21 ·
I ended up capping both ports today. I couldnt really tell if it was running any different than with the hose, but I like the idea of having each port isolated from the other one. At least to eliminate any possible air/vacuum going to the other carb or something.

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