Hey guys I知 hoping you could give me some advice on an issue I知 having with my 2004 kfx 400.

issue I知 having-
i can clean the carb and it will run great for about 10 min then it will only start/idle/and run with the choke half on. And when I say it runs I mean I can only give it a tiny bit of throttle otherwise it will fall on its face and die. So I drained the tank and added an inline fuel filter just for fun. I thought I had sand or something in my gas. But over and over this issue keeps coming up. And the only way to resolve it is to clean the carb and after 10 min of riding I知 back to square one.

mods to the quad
-big bore kit
-slip on exhaust
-previous owner took the air box lid off

keep In mind these mods have been on for a couple years and no issues at all as far as performance. Just within the past few month this issue started. The only thing I have changed is I put 87 octane in it rather than Rec fuel 90 octane. But with the issues I知 having I don稚 see that being a reason.

I致e also replaced the coil pack and changed spark plug. Valves are within spec.

ground issue?
cdi box?
faulty new coil?
gas?


any advice would be greatly appreciated. Thanks for your time