rd350 petcock won't turn off completely

[kramdua]

75 rd350. the petcock leaks fuel out of nipples when turned off. It's more of a dribble that just leaks enough to be a mess. so if you remove the hoses to do a repair you need to cap off the petcock outlets with a vacuum cap. I've been through it a couple times and replaced the seals. it still leaks. i was thinking today that one of the screws to the fuel tank could not be sealed and fuel could be leaking past the threads and into the bowl of the petcock. would that make it not turn all the way off i don't know yet.

[SoCal250]

Leaking screws could cause a seep because they go straight into the tank from the bowl cavity. Are there gaskets on the screws?
I'd be more inclined to think it was caused by the round rubber valve gasket on the selector not sealing properly. Does the valve gasket (137-24523-00-00) still have the raised ridges around the holes? Is the wave washer still in there between the selector and outer plate?

[m in sc]

use sta o seals ont he mounting screws. 'sealing' the threads doesn't work well, if at all, its a straight thread, they don't work that way.

worst case, buy a reproduction fuel tap from john at economy, i have 2 im running. cheaper than hydrolocking a motor.

[kramdua]

thanks for the reply.
yes the screws have the seals on them. first of all i disassembled the petcock when i first noticed the leak. i know what you are saying about the detail of the seal with the 4 holes. i inspected it carefully with a magnifying glass. not one crease or cut in the raised part of the seal. put it back together with dielectric grease and still the same result. i bought a reseal kit from john and replaced all the seals.
same result. the housing and all hard parts are in excellent condition. maybe i am over tightening the screws causing the seals to be deformed. I would like to fix the original because it is in really good condition. i think tomorrow i'll drain it and take a look at the seals.

[m in sc]

the 'wavy' washer may not be putting enough pressure on the sealing face. you can, carefully, re-bend it a bit to give more tension. also, make sure the back face of the lever that seals is smooth, if you have a whetstone, smooth it out.  .02

[Economy Cycle John]

There should have been a new wave washer in the kit in addition to the seals

[kramdua]

yes the new wavy washer was also installed at the time. the kit was complete with everything.
i am going to check into it and let you know the outcome.

[Striker1423]

I got my repo one from HVC before I knew about EC (sorry John). It's been just fine. The only petcock I had to "rebuild" was my GT750 one. For being as popular as that bike is, there's not much in terms of aftermarket parts for it. Just reinforced the point that I lucked into the RD as my step-up bike (from the G3) 6 years ago haha.

[kramdua]

update. i drained the tank and took off the petcock bowl. with a mirror i could see one of the mounting bolt orings was bulged out. i went ahead and took the petcock off and took it apart just to make sure everything was good. i had new orings so i added a small washer to each screw, installed lubricated orings, and put it back together. so far no leaks. i felt a washer would help the oring to seal better than having it rest directly on the head of a turning screw.
thanks for your help,

[msr]

m in sc has already mentioned these, and I can confirm - they are magic: https://www.mcmaster.com/products/stat-o-seal-washers/

[kramdua]

general motors and other makes use that type of sealing washers in their air conditioner lines. if they can hold 300 psi i am sure they will seal a fuel leak.
thanks,

[m in sc]

yup. also great for oil line banjos, and drain plugs.