I have an 07 Arctic Cat 400. Non DVX. It’ll turn over and backfire through the carb. I have verified timing, tried in both positions. 180 out. Carb is clean but it’s an EBay special. But I have tried another carb (different from a 350 Rancher) with the exact same results. I have also verified valve lash, good fuel, good plug, compression is about 110. I’m about to my ends with this things?!? Any ideas?