1970 Honda CL450 left carburetor gas leak

[jedhiggs]

Hey guys, whether the motor is running or not, if the petcock gas valve is on, gas starts leaking steadily out of that tiny hole on the very bottom of my left carburetor. Might this be something I can adjust from the outside or do I have to take it apart? THANK YOU!!! See video link below of leak.

https://www.youtube.com/watch?v=Vi2ZxMx3Ffw

 

[carnivorous chicken]

Either a stuck float valve, stuck or damaged float, or cracks in your overflow tube. If it's a stuck float (caught up on the edge of the gasket, for example) a light rap with a mallet might work. If not, pull that bowl and have a look.

 

[jedhiggs]

Either a stuck float valve, stuck or damaged float, or cracks in your overflow tube. If it's a stuck float (caught up on the edge of the gasket, for example) a light rap with a mallet might work. If not, pull that bowl and have a look.

Thanks so much! Will definitely give it a try and a look.

 

[jedhiggs]

Either a stuck float valve, stuck or damaged float, or cracks in your overflow tube. If it's a stuck float (caught up on the edge of the gasket, for example) a light rap with a mallet might work. If not, pull that bowl and have a look.

SO I just got home and the mallet knock didn't work but what I did notice was affecting the amount of gas leaking out of the carb was the FUEL SCREW! I had turned it in ~1 turn yesterday just before noticing the leak. So I backed it out ~1.5 turns this afternoon and it stopped. How the hell does the fuel screw affect a gas leak when the motor's not even running??

Thanks again

 

[Flugtechnik]

What screw are you talking about? Dry off the carb, slowly turn the gason and see if you can see where the gas is leaking from.


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[jedhiggs]

What screw are you talking about? Dry off the carb, slowly turn the gason and see if you can see where the gas is leaking from.


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In the old school manual, it's referred to as a 'pilot screw' but it's basically a fuel screw since it's on the engine side of the carb. And there is a tiny little hole at the bottom of the carb which must be some drain or release function but it's coming out way more than 1 or 2 drips... Gonna have to take it apart. Thanks!

 

[Flugtechnik]

I can't imagine why opening the idle mixture screw would stop a leak, unless that is allowing the gas to flow into your engine instead of out of whatever leak you have.

Taking it apart is likely your best bet.


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[jedhiggs]

I can't imagine why opening the idle mixture screw would stop a leak, unless that is allowing the gas to flow into your engine instead of out of whatever leak you have.

Taking it apart is likely your best bet.


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Thanks, will do. Hopefully I can get that carb out without having to take the pipes off which are somewhat blocking it.

 

[Whitey80]

You can pull the carb on a CL without pulling the pipes.
The rubber boot from the airbox is plenty flexible and there's enough room to disconnect the throttle cable pretty easily. Done it plenty of times.

Make a cardboard or plastic measuring gauge for the 20mm float setting as per Clymer manual. Quite nice to have around if you intend to keep the bike for a good bit, and definitely if you actually trail ride and beat on it like I do.

 

[jedhiggs]

You can pull the carb on a CL without pulling the pipes.
The rubber boot from the airbox is plenty flexible and there's enough room to disconnect the throttle cable pretty easily. Done it plenty of times.

Make a cardboard or plastic measuring gauge for the 20mm float setting as per Clymer manual. Quite nice to have around if you intend to keep the bike for a good bit, and definitely if you actually trail ride and beat on it like I do.

That is AMAZING news. Really a huge help, thank you!!!

 

[Flugtechnik]

Now that I can see the video, it looks like you are missing the bronze overflow tube that goes in the hole on the bottom of bowl. You are supposed to be able to connect a small fuel line there to direct any overflow down to the ground.


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[Flugtechnik]

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[jedhiggs]

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THAT's interesting. But the carb on my '70 CL450 is stock and only has that "nipple" coming off the bowl with a tiny hole for releasing. There's definitely not a spot for that brass piece I see on yours... The weather was bad yesterday so I didn't get to open her up but I definitely appreciate reference photos and can't wait to see what the hell is going on! Thanks again!