420 efi rancher hesitates

Hi guys. I have a problem where the quad will start and run well for about 5 minutes and then it dies. On inspection the airbox has oil in it (quite a lot). The oil is pumping through the cylinder head breather hose. This problem first happened suddenly. I have since done the top end including, piston, gaskets, rings and valves. I have also done the carb (not that I thought that this was the problem). The compression seems normal. The only thing that I can think of, is that I did not grind the valves well enough. Anyone experienced this? If so, how did you fix it? Any other thoughts?

2022 Sector 550, 414 miles on it and the gas gauge reads empty.  I topped off the gas and it didn't change.
There is no fuse that I could find.  No access at the gauge cluster.
Wiring on the top of the tank looks good, properly connected.
Could the sending unit in the tank be stuck or broken?
Has anybody removed the tank lid?  Any tricks?  
Any other ideas?
Thanks for any help,
Clyde

What should I do about this , bad oil leak where the filter cover bolts on . Can I use some gasket maker 

I have been exploring all the options available, so many, its hard to choose. I have kind of narrowed it down to the Honda Pilot, Subaru Outback, and Kind of looking at the Outlander, although its a little small,  the new one is nice looking. Just wondering if anyone has any recommendations or gripes with any of these rides. I have driven Jeeps for the past 25  years and they have been great, but their price point has gotten to high. Expieriences good or bad would be helpful. Thanks!

Just thought I'd start a new thread for newbies to the site!
If you're new here, tell us who you are, where you're from and what you ride!!!
Lets get to know each other a little better shall we?
I'm not new to the site, obviously, but...
I'm Kristin from Denver!!! I ride a 2008 Yamaha Rhino. She's my muddy baby!!!!!! Several aftermarket parts on her. She's good to me! We try and ride every weekend. This weekend we're off to MOAB! :woot: