I can't wait for the fancy welded manifold so I'm making one from PVC

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You guys are gonna love this one.

I haven't messed with it for a couple days so I went out to make sure the battery was charging, etc. and got a whiff of gas when I open the garage. Hmm. That's not normal. I look at the right side of the engine and my nice engine paint that I was so proud of was destroyed. Gas drip. I see a drop fall from where the manifold goes into #3 intake horn. Not good. Loosen intake horn clamp. Much gas. Loosen intake horn screws at the head. SPLOOSH.

It was full from the intake valve to the top of the horn. So was #1. :doh:
141003_0000.jpg

That's gas. Here's what it looks like now.
141003_0002.jpg

I removed all the horns, I got out the gas and pulled the plugs. The left bank didn't have any in it but if the valves were open it got into the cylinders. I'll let it evaporate overnight- too much fumes to risk cranking it.

Both my previous bike and my current one have vacuum controlled fuel valves so I've gotten bit careless about shutting them off. Not to worry, it has a fuel pump so it's not going to get up to the carb if I do leave it on, right?

Wrong. So very, very, wrong.

The damaged paint did show 2 possible leak locations in the manifold. They appear to be right where I said it was weakest, where the cut down sections had very little mechanical strength. I probably cracked them when I wrestled the horns on. So a bit of a setback, but I didn't have any other plans for tomorrow anyway.
 
It's good you found it before you tried to crank it. Thankfully it DID leak so you got the alert. Keep us in the loop how it's going.
 
hmmmmm this is set back .....take a deep breath ... look everything over good ....personally i dont like using the stock intake horns ....it been my experience that they can be constant place trouble and sealing ....i know your saying it is joint failure on pvc ...lots of vibration going on while riding..... motor and road ...i like the way the system goes together but ...after watching the cutting of the lapped joints down this really takes the stability and structure down to level i dont think much of.........im glad your posting everything so we can see everything ...seems like carb is in suspect too shoudnt have leaked that much gas in ....
 
Yeah, I thought that too. It has a needle valve that's supposed to stop fuel when the bowl is full, so why didn't it? :headscratch: I think it warrants opening the carb for a peek. This is a used carb so there's no telling if it works beyond what the seller said. A blocked passage would also explain the inability to idle. The best thing to do is order a rebuild kit.
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=132876#p132876:t4n1kh4d said:
chuck c » Sat Oct 04, 2014 6:12 am[/url]":t4n1kh4d]
Yeah, I thought that too. It has a needle valve that's supposed to stop fuel when the bowl is full, so why didn't it? :headscratch: I think it warrants opening the carb for a peek. This is a used carb so there's no telling if it works beyond what the seller said. A blocked passage would also explain the inability to idle. The best thing to do is order a rebuild kit.
Click to expand...
And why so much fuel.
Seems there could have been a syphoning thing going on there?
 
[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=132876#p132876:2vv14o0r said:
chuck c » Sat Oct 04, 2014 11:12 pm[/url]":2vv14o0r]
Yeah, I thought that too. It has a needle valve that's supposed to stop fuel when the bowl is full, so why didn't it? :headscratch: I think it warrants opening the carb for a peek. This is a used carb so there's no telling if it works beyond what the seller said. A blocked passage would also explain the inability to idle. The best thing to do is order a rebuild kit.
Click to expand...
This really highlights the advantage of a new stovebolt carb which can be fully jetted for the best suitability for a GW. I really can't see much point in going to a single carby unless you are getting the advantages of a new product :yes:
 
And why so much fuel.
Seems there could have been a syphoning thing going on there?
Click to expand...

For this to happen the needle valve would have to fail to shut off the gas when it was full. Several things could cause that, leaking float, float stuck, needle dirty, etc. But what the heck would allow a carb to actually siphon?

I have noticed the tank gets slightly pressurized. Every time I remove the cap it takes a bit of extra effort, hiss when it's turning and the cap pops up when it gets to the open position. It's got a couple psi in there. Could that pressure force gas past the pump, needle valve, and down the throat even if they all work correctly? The tank must have a vent. It could be blocked.

There have been a hundred times I've worked on machines and dismissed two things as separate, unrelated problems, only to find out after much toil and sometimes expense that both symptoms were caused by the same problem. Is there a chance this pressure in the tank, massive flood of gas, and inability to idle are related? 2 out of the 3?
 
Possible. The stock vent in the gas cap is a one way deal letting air in but not letting air fuel or vapor out. Shut down cool and the tank will pressurize as it warms. If fuel valve is on it will have enough pressure often to push gas in after shut down.
 
Even so, the needle valve should stop the flow. The pump puts out - what - 4 to 7 PSI? I'd tear the carb down and clean it up good. Get that rebuild kit. Try running it with the cap off the tank, or at least loose so there's no pressure buildup.
 
Yeah, if the needle valve can stop the pressure from the pump it should be able to stop the 1 or 2 psi from the tank IF it's working properly. It looks like that carb is going under the knife.

Now that I think about it, when I was priming it to try starting it I hooked an old syringe body (a big one) directly to the carb with a few inches of tube. If the needle valve was working it should have stopped accepting fuel and I would have seen it stop flowing. Now, I don't know if I put enough in to lift the float and shut it off but I did not see it stop. It's possible it's never worked and if I overfilled the carb it just went on through but I didn't put in enough to hurt anything. That needle valve is not working.
 
I am disillusioned with PVC. I'm sure it can work fine but I want to try something else. Has anyone tried copper plumbing pipe and fittings? They cut easily and soldering makes airtight joints. Easy to bend. Hmmmmmm. :headscratch: A trip to Lowe's is in order.

Adding some plumbing for manifold heating would be easy too.
 
[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=133055#p133055:2cbrsuhp said:
dan filipi » Mon Oct 06, 2014 8:45 pm[/url]":2cbrsuhp]
I have seen copper used and I can't think any reason not to try it.
Click to expand...

I just saw one, the price! :swoon: I knew it was bad but holy carp!
1" elbows $8+ Ts $11+ They didn't have any crosses. I'd have to order the parts which kinda goes against what I'm trying to do here. I guess there's no choice unless I can find a plumbing supply place around here that has hours I can get there and sells to the public.
 
I drew this not knowing the real sizes of the parts. I estimated. I've seen this design before and while it doesn't look great for smooth flow it has the advantages of being easy to build and fit. The 7* angle is a snap, that gave me a lot of trouble in pvc. A bit of shopping online and I can get the parts for about $35. I think I have a hunk of pipe, if not Lowe's sells 2' pieces. It should be possible to solder/braze the aluminum flange to the copper. I might take a crack at this design in pvc.
copper manifold.JPG
 

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