LEAKS AGAIN

[chiz]

Howdy got back from 2 day tour of the Haliburton and Madawaska highlands north and east of Toronto I was shiteing  bricks, in my 40's 50's and 60's no problem would'nt have cared but time moved on and wondered continually when would the regulator starting motor alternator or ignition leave me stranded on this old 84.. not a hiccup things were made better back then rite?
     Parked her on sidestand in garage moved her a few feet next day when low and behold the carb started pouring this has happened 3 times in the last couple of months, clearly I am lacking some skill and knowledge as I have not solved this problem long term.
 As in previous incidents the leakage coincides with failure of the vacuum shut of fuel tap, was briefly confused by this, wrongly thinking the fuel tap was the cause of the leak. Anyway replaced the float seat and needle of offending carb and fitted a new petcock diaphragm the petcock still leaked at first...took it apart cleaned it again and scrubbed the o ring seat with a q tip it sealed after that.
   Question is what are the tricks in rebuilding petcock? and could the sealing surface of the 'o'ring be minutely etched over time? and could the seat surface be polished up with some kind of agent? Any tips here would be most welcome.
 I dont really know why a new seat and needle should start to leak, crap seat 'o' ring and needle?.. weird atmospheric phenomenon affecting one carb?.... some latent trapped vacuum source effecting the petcock??? Grasping at straws here... thanks for reading Lez.

[Pat Conlon]

I have not had good luck rebuilding vacuum petcocks.
I said (after 2 attempts)  Screw it, the grief and worry is not worth it. So...I bought a new one from RPM.
Besides,  I think 35 years is a reasonable life expectancy considering the hot environment of the petcock.
When they become no longer available, no worries for me, I will have converted over to a fuel pump on my 84.....no more vacuum shenanigans and the ability to run a real fuel filter will be worth it...

New float needle, needle seat and o ring means you can rule out those from your list of possible culprits....
Still on that list is your
1) float level (misadjusted or leaky float?)  and/or
2) crap in your gas tank (or bad gas) that's getting between the tip of the float needle and the needle seat causing the needle not to seal. It doesn't take much, especially with a leaky petcock.

My recommendations:
1) Check your gas tank for rust. Clean, etch and seal if necessary.
2) Replace that petcock, http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3A36Y-24500-01
3) Then run a tank of Seafoam thru your engine. I've had good luck with Seafoam.
4) Never keep E10 ethanol laced fuel in your bike...never...it's ok while traveling but when you get home, drain that shit out of your tank and fuel bowls.


For reliability, do the Transpo Voltage Regulator Mod. we show in the files. It's easy.
https://fjowners.com/index.php?topic=661.0
Your battery and light bulbs will thank you.

Cheers

Pat