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Two questions/mysteries
- Thread starter thielb
- Start date
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Rockrider
XS400 Enthusiast
I have same bike mine has only one barb on the left intake it goes to pet cock for vacuum from what I've read. The one on right stays plugged. Am I seeing two on the left intake boot or is the plugged one on the right intake boot just behind it? Can't trust my eyes only seeing one angle lol. When you sync your carbs you hook the manometer to both of them to see which one is pulling more and adjust with that sync screw in middle of carbs. I don't know much but I know it wont run without the one being plugged LOL. That lil metal pc yea I'm lost I didn't find one of those hope that's not a bad thing. My airbox is missing screws so honestly I have no idea. Check boats.net for diagrams.
The first thing is the spring which holds the air filter in place inside the airbox.
I think that the 2 lines might be for vacuum to the petcock. I think one is always capped and the other is connected to the petcock if the petcock is the type which uses vacuum to open the flow of fuel. Since you have a secondary, down-line fuel shut-off, I suspect that either your petcock was replaced with a non-vacuum one, or, it no longer operates properly. In either case, the 2nd vacuum line would need to be capped too.
I think that the 2 lines might be for vacuum to the petcock. I think one is always capped and the other is connected to the petcock if the petcock is the type which uses vacuum to open the flow of fuel. Since you have a secondary, down-line fuel shut-off, I suspect that either your petcock was replaced with a non-vacuum one, or, it no longer operates properly. In either case, the 2nd vacuum line would need to be capped too.
thielb
maxim
thanks lou that helps alot. I've been having petcock problems a ton actually, it just dumps fuel when it's at "on". could that be related to this chopped/plugged vacuum line?
if it's chopped and plugged, and the petcock would be working properly, it would result in not supplying gas at all (turning off your petcock permanently in the ON position). Since there is a problem with your membrane inside your petcock, this 'switching off' function of the vacuum line doesn't work anymore. Which makes the vacuum line useless, one could say. But it's not causing any problems, it's just out of use due to other problems inside your petcock.
thielb
maxim
thanks willem, so when i rebuild my petcock, i can go ahead and hook this back up and everything'll be fine n dandy?
In theory, that should be the case ... in a perfect world, with no design flaws, no past modifications and, no PO MacGyvering.
But, you are an xs400 owner. Always be prepared to drop everything and make a post on this thread:
If your petcock is sufficiently messed up, you can have gas sucked into the intake through the vacuum line. That would make the engine run rich, or maybe even not at all. This could be the answer to why the line was cut and plugged.
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