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Discussion Starter #1 (Edited)
Hey everyone, so I have been searching high and low for this information. None of the manuals have a single explanation. Our bikes are old and forums are filled with "Shit...my bike doesn't have that, should i?" so it's been a pain in the ass to figure all this out. So I want to just sort it once and for all, with a single image for any newb like me that feels overwhelmed with hoses :)

I think I've got most of the right, there are 2 more hoses that I don't know what they do exactly, and more importantly, where they should go. They are labeled/circles/lined in BLACK in the image below. The T fitting behind FUEL IN (RED top right photo), I have a hose connected there, it's about 6 inches long, goes nowhere. And then in the diagram on the bottom left, there is a single hose that seems to connect to a Triangle Box and then somewhere on the carbs? One of the triangle boxes does indeed have Nipple Out...but no idea where that should go.

EDIT - reading more forums, it seems like that T fitting in the photo top right, is the same hose that I don't know what it is in the bottom left diagram, that goes into the Traingle box. So perhaps both my Purple lines sit in their little box with the 4 holes, then the T fitting behind Fuel In, routes via hose, to the nipple on the OTHER triangle box?
976588
 

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If I'm not mistaken, the second T is to vent the float bowls. I don't know where this is connected in stock form but if I had to guess it's probably one of the plastic triangles just like the lines marked in green, so it too is vented to still air.

In case of carb overflow or a bike tipover, fuel can come out of there.
 

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Discussion Starter #3
Makes sense..one of the triangles has a nipple and is sealed. Make sense for it to hold the fuel from the floats in a tip over.

So I'm gonna set mine up like this but it does seems like a lot of hoses to do 1 job.

As a mod...could I just put the 2 large purple hoses..into a Y..and then add a little air filter and mount it in still air?

I believe someone else has said they just run those all the way to the ass..etc. few people have the triangle box setup it seems...30 years on

Sent from my SM-G950U using Tapatalk
 

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The large purple ones are important, even slight pressure fluctuations would probably cause erratic behavior of the slides. I guess a filter mounted somewhere out of the wind would work though.

The plastic T vent is not as critical, I guess in theory strong suction or pressure there could lift or lower the fuel level in the bowls a bit, but if you just vent that line to atmosphere out of direct air stream I'm sure it'll be fine. Mine never had anything connected there when it still had Mikunis.

The green lines are essentially just-in-case drains, so route them away from the engine somewhere
 

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Discussion Starter #5
Right on, thank you, in that case I'm going to order the proper little catch screen thingies for those hoses. I have 1..I suppose based on what I've read they are either little filters, or one way valves of some type, can't remember. At any rate, it seems that I have it straight and can just build up the proper hoses and be good to go. I guess considering the Y into 1 on the fuel lines, there are just 9 hoses.
 

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Discussion Starter #6
Ok here is the final version the ORANGE line is "special" in that it's the only drain line that drains into a confined space instead of the ground. If that's all it does, and it certainly seems like that's all it does, the it COULD be part of the "Drain Ground" path. The Triangle Box it connects to is NOT sealed, there is one 5mm hole in it, so that hose is not part of a sealed system regardless. I feel it could be "GREEN" in my graph as well. There is Probably a tidy way to get 4 Drain Ground lines setup in a much cleaner fashion than stock. for me, I'll start with stock.

But I hope this thread pops up from time to time and can help people in ONE image...see how to route these things!

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Re the purple vent lines, in the interest of cleaning up the routing when I was replacing all the lines on my '94 DB2 (BDST 38 Carbs), I 86'd the plastic triangle vent boxes (15 and 13 in the pic) and simply terminated each line into its own aftermarket can filter. Wanting to eliminate connections where I could, I also 86'd the inline filters in the drawing - which are no more than cans with screens in them - since I now had the end filters. Cannot see in the drawings here the inline, incoming to carbs fuel filter (would be on the red line here) that the DB2 had, which was total toast on the bike and NLA from anyone (Ducati, Bimota, Mikuni), so I plugged in a "Mr Universal" filter, with the arrow pointing towards the Indians. I also 86'd the airbox and used appropriately sized and sealed can intake filters. After an ultrasonic clean and a total jet and gasket fluff up, the bike has never run better.....
 

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Those tiny cans are just screens , except the one from the fuel tank breather, it has an arrow on it for correct installation. It’s a one way valve. the lines that are vents I removed the tiny screens , because they plug easily , and replaced them with larger fuel filters that can be cleaned. I routed all air vents to the tail. I routed all drains under the bike. I routed the engine breather high on the right side of the frame to a K&N breather using the stock hose. I have a problem with tiny wasps that build mud nests in the tubes so I can’t leave them exposed.
 
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