You can buy the hydraulic fitting aluminum dust caps that are very close to the caps used on Hornet sprint karts. I have bought some of these caps and they fit my Hornet tanks and look great. The main difference I see in them is that there is one less thread on the cap and they don't have the vent hole drilled yet. Unless you hold one of these caps next to an original Hornet cap you will not notice the missing thread. One less thread does NOT affect their fit to a Hornet filler neck. They don't come with any sealing device, but you can add a small baffle plate inside the cap and then use an O ring or a hand made gasket from cork or heavy gasket material. These are made by Capsnplugs. Their minimum order is 900 caps. For those of you needing less than 900, you can buy these in a package of four from ANplumbing.com.
Anplumbing.com part #FBM9924 The cost is $7.99 for the package of four plus shipping. Sales tax will be added if you're ordering from within California.
Anplumbing.com part #FBM9924 The cost is $7.99 for the package of four plus shipping. Sales tax will be added if you're ordering from within California.