Gas frame Petcock hole doesn't fit stock petcock or a high quality one. What should i do?

Stock762

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Feb 19, 2018
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This gas frame i have doesn't have the proper threading for the stock petcocks or a high quality one i ordered from MZ miami on their ebay. Even though i figured that both petcocks are the same threading because they fit into a regular kit gas tank. What should i do? I really don't want to try and tap the hole because i already have most of the bike assembled and would have to remove the engine and everything. Or i can try and figure out the threading and find a petcock for that threading
 


gary55

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Nov 27, 2012
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Chances are it's just poor quality control at the factory. You're probably going to have to fine out what the threads are on the petcock and match them on the bike with a tap. Maybe someone will chime in with a better idea. Until then I would take your petcock to a hardware store to find the proper thread pitch. Iy could be npt or metric. Probably metric.
 

wheelbender6

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You can use off-the-shelf brass fittings from the hardware store to connect the fuel line to the tank. Then you can add an in-line fuel petcock.
-I think the brass fittings I used were a combination of natural gas and waterline fittings.
-The brass fittings were reducers, threading one inside the other, until fuel line diameter was reached. It was totally trial and error.
 

Stock762

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Thanks for the suggestions. I'm currently waiting on a m10 by 1.25mm petcock just incase it happens to be that bigger thread type since it looks like a bigger threading in the frame. Last resort will be tapping it, theres not even enough room to twist the tap with the tool it comes with? I would have to do like half turns at a time?
 

gary55

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Thanks for the suggestions. I'm currently waiting on a m10 by 1.25mm petcock just incase it happens to be that bigger thread type since it looks like a bigger threading in the frame. Last resort will be tapping it, theres not even enough room to twist the tap with the tool it comes with? I would have to do like half turns at a time?
I suppose anything is possible with these Chinese frames. I know the threads on the stock petcock is 10X1 because the threads match up perfectly to the 6X1 intake bolts.
 

Stock762

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Thanks for the response with the socket and ratchet on the tap. So the m10 by 1.25mm petcock I ordered off ebay actually fit! (was tight) so I took it outside and put gas in the tank. It hasn't leaked for couple of hours i believe its all good i added the white tape to the threads also but unfortunately I forgot to put the filter on the valve that it came with that goes inside the tank because i didn't even think at the time it was going to fit, but hopefully the inline filter will be fine. I vacuumed the tank out before i put gas in.
 

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Stock762

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Feb 19, 2018
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Man, woke up this morning to check for leaks. It's leaking very slowly was wet an could smell gas.. ughhhhhh. Gonna have to take it off an figure something out. The rubber seal on the petcock nut is kind of crunched i will try and make that flush.
 

gary55

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Might need to use a fiber washer. Some of the petcocks came with a rubber seal that was hard and worked well, some with a soft rubber seal that squished out when tightened and some have a fiber washer that worked well.
 
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