97 gsi 717 help! Major Backfiring

[Dschall3]

Hello everyone, I am new to the forum, as well as new to jetskis as well. I bought a 97 gsi a couple of weeks ago. The ski is a little rough, but the owner said it ran a couple of years ago. I tore into it and changed the fuel lines, new oil filter, new battery, etc. I also ordered the mikuni carb rebuild kit and rebuilt the carb. As of yesterday it turns over and idles. I messed with tuning up the carb and it idles pretty well. When you rev on the throttle there is some major backfire right away. After a few minutes of trying to rev a little more it eventually dies. I googled some about the air/fuel mixture and worked with that some and still nothing. I feel like I am missing something simple, or possibly there is something I skipped over. I am very new to this, and any help or guidance or anything would be very appreciated as I am getting real eager to try and put this thing in the water. Thank you in advance!