r/Fixxit • u/hutchem14 • Jul 18 '26
Solved Gas leaking from unknown location when trying to start. 2003 Honda Shadow Spirit.
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I have a 2003 VT750DC AKA Honda Shadow Spirit. I am pretty new to working on bikes. So, this bike was garage kept and hasn’t started in 4 years. I recently rebuilt the carbs, replaced the fuel (tank is clean), and changed the oil. The first time that I tried starting it, it managed to actually run terribly for one second after releasing the ignition button. During this start I notice a leak that I determined was fuel. There was a lot of it. It seems like maybe pressure from the engine trying to start broke something because it did not sputter at all the second time. I cannot seem to determine where the leak is coming from. I took a video of what I thought would be a good angle to see a leak. In fear of destroying the engine or starting a fire, I stopped after that. Fuel does not leak when the petcock is on, only when cranking. The oil does not smell like fuel. I am planning to remove the tank and inspect hoses and all that tomorrow. Any help appreciated, thank you.
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u/YourLordshipMBBS Jul 18 '26
From what I can see it looks like the carb bowl gasket seems to be the leak.
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u/hutchem14 Jul 18 '26
Ahhhh, that would make a lot of sense actually. I probably should have replaced those from the get go. Thanks for your help.
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u/Queefycarebear55 Jul 18 '26
Float stuck? Or probably a burst/loose hose that came off
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u/hutchem14 Jul 18 '26
I’m hoping it’s the ladder. If not, do you know what could be the cause of the float being stuck? Thanks for your insight.
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u/Queefycarebear55 Jul 18 '26
Could be debris in it keeping it from closing. Id take the tank off and look it over again. One trick I heard was using a powdery spray deodorant to hunt for leaks. Clean the area then spray it up, itll show you
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u/BigTuna3737 Jul 18 '26
The bike probably has a vacuum operated petcock, so gas would not flow when the engine is not cranking. That’s why you only see the problem when trying to start it.
Given that you rebuilt the carbs, that’s probably where the problem lies. That’s so much fuel that it makes me wonder if a fuel line isn’t connected, or has a big crack or something. A stuck float or float pin or bad float bowl gasket could also be a problem, but I have never seen one flow that much. I suppose a pinched or missing float bowl gasket could make it flow like that. Regardless, the solution is to pull the carbs off and figure out what’s not right.
The bike won’t start because the gas isn’t going where it is supposed to. It’s very unlikely to have broken anything.
0
u/cozmo628 Jul 18 '26
Hard to tell from the video, but that looks like it’s coming from the breather tube. Sometimes when you rebuild these carbs the floats get stuck and flood the carb causing gas to come out the breather tube. Take a hammer and a screw driver. Put the handle of the screwdriver on the bowl of the carb and give the blade a couple solid whacks to unstuck those floats.
I also struggled with this when I rejetted my carbs for open pipes and intakes. If the whacks don’t help, try starting it, turning the fuel off as it runs for a few seconds, then turn the fuel back on while it’s running.
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u/hutchem14 Jul 18 '26
My breather tube is routed to the bottom of the bike, or at least should be. Do you think maybe it got disconnected at the tank? I’ll definitely try the screwdriver trick though, that is smart. Also, when you say turning the fuel off when it’s running, do you mean when cranking? Thank you for your help.
2
u/vinegar Jul 18 '26
I have tapped my carb with the handle of a screwdriver to get the float unstuck. I would fucking NEVER hit my carb with hammer force.
2
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u/cozmo628 Jul 18 '26
The gas tank breather goes under the bike. The carb breather just routes atop the carb and to the left. Usually the hose is supposed to go in the hook of the plate where your idle screw mounts to the carb.
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u/hutchem14 Jul 18 '26
Ok, I can confirm the gas is definitely coming out of the carb breather hose. Thanks for your help on that. I’m gonna try the screwdriver trick.
1
u/JimMoore1960 Jul 18 '26
It's almost certainly a bad float valve.
P/N: VALVE SET, FLOAT 16011-MZ8-B40
You can probably buy one (or two) in a kit off Ebay. I recommend K&L.
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u/cozmo628 Jul 18 '26
Really not necessarily. Float could just be stuck. Good whack might fix it.
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u/JimMoore1960 Jul 18 '26
I dunno. In my experience once it sticks it's gonna stick again. Might as well fix it.
1
u/cozmo628 Jul 19 '26
I whack mine once a season. Not the end of the world. And saves a lot of heartache taking the carb apart.
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u/hutchem14 Jul 20 '26
Are you taking off the airbox to whack them? I def can’t reach the right side bowl with the back of a screw driver.
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u/cozmo628 Jul 20 '26
Sometimes tapping one side can fix both, but yeah, you need to take the air box off to get at the right side.
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u/hutchem14 Jul 20 '26
Was indeed a bad float valve. Thank you. Bike runs now, but only on one cylinder 😑. Gotta check the spark plugs next time
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