Scooter Doc
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Post by Bong on Jan 6, 2011 17:48:13 GMT -6
My little 50cc QMB has had some problems. I have ended up replacing the Petcock 2x now.  I got a Briggs and Stratton manual fuel valve as a gag gift for Christmas. The funny part is now I want to use it. Can I just pull the vacuum petcock and replace it with the shut off valve? What about the vacuum line? Has anyone done this? and what to do about the vacuum line? Pics always help if this can be done. Anyone else run petcockless? |
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Post by Alleyoop on Jan 6, 2011 18:50:50 GMT -6
Yes, you can run without a petcock and put on a shut off valve. Just make sure that the hose from the tank to the filter and to the carb are NOT LOWER than the Carb. Many have done it just make sure at least in the summer when it is hot and you park it you shut the gas off. Otherwise it may flood the carb and you will have gas all over the place.
Alleyoop
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Scooter Doc
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Post by Bong on Jan 6, 2011 20:47:43 GMT -6
My tank is located at the rear above the carb. I would like to run a line from tank to filter, Filter to Shut off valve to carb. There is a vacuum line on the petcock though I don't know what to do with. Can I just plug it at the manifold and be ok or will this cause a problem?
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Post by Cruiser on Jan 6, 2011 21:22:24 GMT -6
Blocking off the vacuum line at the manifold should cause no problems.
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Post by Alleyoop on Jan 6, 2011 21:25:43 GMT -6
Just a question what kind of carb do you have? If it has a deceleration pump on the right side of the carb that, requires Vacuum. If nothing else is attached to the Vacuum hose coming from the Intake then yes you can just plug it up.
Alleyoop
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Post by Bashan on Jan 8, 2011 6:29:38 GMT -6
I'm a big fan of getting rid of the vacuum petcock, I think they're a source of potential problems. Alley's right, you need to remember to shut off the gas though when you're done riding because if your float valve leaks you have a petro mess in your garage. You got a nice present for Christmas, I use a Briggs & Stratton valve on my Bashan, it works great. Tank to filter to valve to carb is the path I prefer; that's not set in stone but the tank has to be first and the carb last  . Alley is also correct in that you need a vacuum line to your air cut valve on the right side of your carb. In this image you can see the B & S valve, and the red arrow points to the vacuum for the air cut. I use clear on that line so that I can make sure the air cut diaphragm isn't leaking gas although that's rare on a new carb:
Cruiser speaks the truth, NEVER leave an unused vacuum line unplugged, or have a vacuum leak for that matter, it makes your engine run......icky. You can get vacuum caps at your auto parts store, or snip and plug the line with blue RTV....the choice for OCDs everywhere!:
If you need anything let us know, Rich
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Scooter Doc
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Post by Bong on Jan 8, 2011 17:05:30 GMT -6
Thank you for all the help guys!!!!!! Alley- I have a Keihin style CVK carb. I Have a Vacuum line from the manifold to the petcock, and another vacuum line from the manifold to the carb. Again, Thank you!!!! The pics helped allot Bashan. You Rock ;D So, I can just pull the petcock, replace with the shut off valve and plug the vacuum at the manifold, be a happy camper and learn something new. If I shut off the gas about 30seconds befor turing off the engine, A would be thief may never get it to start. He He ;D I just need to remember to turn it back on  |
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I got a Briggs and Stratton manual fuel valve as a gag gift for Christmas. The funny part is now I want to use it.
..BAD TO THE BONE..
. Alley is also correct in that you need a vacuum line to your air cut valve on the right side of your carb. In this image you can see the B & S valve, and the red arrow points to the vacuum for the air cut. I use clear on that line so that I can make sure the air cut diaphragm isn't leaking gas although that's rare on a new carb:
