Look into a stiffer spring for rear as well, itll help throughout all riding. Try a 15 front, and if it's too much , go up 1 at a time in rear. Tire pressure can make big difference as well , depending on sand conditions.
Yup. My 75hp 4mm dune port stock arm bike loved 15/41 gearing and I was 225# with 20/10/10 8paddle haulers. Either way, if you're actually trying to "drag" that thing, those tires are not the ticket
My uneducated hillbilly input, clean it all good, run it, keep eye on it for any leaks to determine if its crack or flaw. If it was a crack, wouldnt a leak down test show ?