when testing carbs for leaks, how do you know when you've filled the carbs and you have no leaks?

If it's broken or just needs tweaked

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juntjoo
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when testing carbs for leaks, how do you know when you've filled the carbs and you have no leaks?

Postby juntjoo » Wed Jan 17, 2018 8:47 pm

I have an extra bowl cap to fill up four times to keep track of what's going in. From what I understand when they overflow it's supposed to go out somewhere? I've only read this in forums. Never seen any procedure in any of the manuals.
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Folsoml
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Re: when testing carbs for leaks, how do you know when you've filled the carbs and you have no leaks?

Postby Folsoml » Thu Jan 18, 2018 6:12 am

I will usually hang the entire bank on something that allows me to see it from every angle (especially from the bottom). I have a lawn mower gas tank that I will fill with enough gasoline to ensure that the bowls fill completely. I will run a length of fuel line to this tank, and hang it above the carb bank. I will then let it sit for a while and keep checking it for leaks.

When you first start letting the fuel flow to the carb bank, take something like a screwdriver and tap the float bowls with the handle. The float needles will often hangup and not seat properly at first. Tapping the bowl helps get them to seat.

When you are checking on them, you may find fuel dripping from what appears to be one or more of float bowl nipples. Be careful not to assume that it is overflowing and coming out of the nipple itself. Fuel could be oozing from somewhere else (fuel rail--especially if you did not change the o-rings) and just dripping from the nipple. Sometimes the leak is so slow that it is very difficult to tell where it's coming from. I'll make sure the carbs are dry, and take tissue paper and stuff it into the bank. The tissue paper will help narrow down the exact location of the leak. Some people have also used talcum powder.
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juntjoo
Posts: 167
Joined: Fri Nov 10, 2017 6:19 pm

Re: when testing carbs for leaks, how do you know when you've filled the carbs and you have no leaks?

Postby juntjoo » Thu Jan 18, 2018 12:01 pm

Folsoml wrote:I will usually hang the entire bank on something that allows me to see it from every angle (especially from the bottom). I have a lawn mower gas tank that I will fill with enough gasoline to ensure that the bowls fill completely. I will run a length of fuel line to this tank, and hang it above the carb bank. I will then let it sit for a while and keep checking it for leaks.

When you first start letting the fuel flow to the carb bank, take something like a screwdriver and tap the float bowls with the handle. The float needles will often hangup and not seat properly at first. Tapping the bowl helps get them to seat.

When you are checking on them, you may find fuel dripping from what appears to be one or more of float bowl nipples. Be careful not to assume that it is overflowing and coming out of the nipple itself. Fuel could be oozing from somewhere else (fuel rail--especially if you did not change the o-rings) and just dripping from the nipple. Sometimes the leak is so slow that it is very difficult to tell where it's coming from. I'll make sure the carbs are dry, and take tissue paper and stuff it into the bank. The tissue paper will help narrow down the exact location of the leak. Some people have also used talcum powder.


thanks. how much or how do you know until when to pour gas if a float valve fails? watch down the throat? ive got powder. good idea
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GeorgeSweety
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Re: when testing carbs for leaks, how do you know when you've filled the carbs and you have no leaks?

Postby GeorgeSweety » Thu Jan 18, 2018 12:32 pm

As Folsoml said, get ready with your screwdriver handle and if fuel starts to leak from a carb then a couple of sharp taps to the float bowl will normally re-seat the valve. No fuel should come out of the carb throat unless your overflow is blocked and your float valve is really jammed open. If no fuel leaks from any carb you should be good to go, make sure you set your float heights at 12.5mm.

juntjoo
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Re: when testing carbs for leaks, how do you know when you've filled the carbs and you have no leaks?

Postby juntjoo » Thu Jan 18, 2018 4:57 pm

thanks
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