Repairing a Jawa Petcock
Today we will be addressing the Jawa petcock. The petcock used by Jawa is unique in size and fitting, there are no after market replacements. This may be disheartening to learn at first but it's not all bad, in fact, you don't want another petcck, the factory one is probably one of the best ever made! It is a much heavier duty construction than most others, and it is also extremely simple making it a breeze to rebuild again and again. So get off eBay pick up your tools and follow these steps!
1- Disconnect and remove fuel tank, empty contents into an appropriate container.
2- Loosen collar nut (look at the size of that thing!)
3- Remove petcock, clamp gently in a bench vice leaving the lever accessible. (now would be a good time to clean out that rusty tank. Got POR?)
4- Unscrew wire mesh (yeah, it's threaded!) then unscrew the lever retaining nut, the lever and disk valve will come out together.
5- You will see a rubber disk in the valve body with 5 holes, a drywall screw gently twisted in to the center hole will grab that seal nicely to pull it out.
6- Clean out the valve body and all its passages, as well as the screen, and any mating surfaces.
7- Examine the rubber disk seal, if the petcock was leaking or the seal is visibly damaged, find a piece of gas resistant rubber and cut a new one, don't for get to drill the 5 holes. This is the only seal in the whole unit, so if it leaks, this is why.
8- Reassemble, and install petcock and tank.
9- Go do something else now.