Less than a buck at your local Ace hardware... same size as your oil drain plugs. I did mine last year.

 

Is it possible to change both of the O-rings in the check valve without the $99 tool?

 

Yes. I had to drain fuel from tank, remove the center panel, remove the paste to access the fuel pump and filter. Then disconnect the check valve tube and unscrew it from tank.
once it's out you can turn upside down and using a pick blade the lower o ring and then the upper as well. Be careful as the spring and valve piece will come out.
to install new o rings use a long skinny socket. I think i used a 9/32. Place spring, valve and smaller upper o ring into check valve, then use socket to push down in place while holding the collar down. Should seat easily.
then push lower o ring into assembly and use a flat head screw driver to gently push into the groove while holder collar down again.
be sure to grease the o rings so they don't tear going back in.

it's easier than it sounds. I have over 3 hundred miles since i did mine and she runs great.

 

https://www.hdforums.com/forum/ignit...2-softail.html

Hope this is helpful for someone...

Shane

 

Yes, use Viton, especially if there's ethanol present.

 

i envy those of you who could change both with it on the bike. i said fk it and changed the assembly lol.