Hello,
I have a 25hp Intek on my riding mower with 130 hours on it.

I'm getting backfiring through the exhaust on one cylinder.

Fuel pump is good, compression on both cylinders is 145psi, spark plugs have been changed out, diodes check good to the magnetos AND magnetos have been switched from side to side...all to no avail. I even checked the valve clearance (0.005").

Backfiring ceases when the choke is pulled out or the weak cylinder's spark plug is disconnected. I'm thinking that one of the two barrels of the carburetor has some junk in it and causing the one cylinder to run extremely lean. Any ideas out there? Thanks!

The carb vent on the weak cylinder side (#1) was a bit clogged as you can see from the backlighting by my Stinger flashlight...

Thanks for posting the fix deltajetfixer.. I have the same problem and will have a go at it tomorrow with some insight... You made my day..
Best regards
Yachtsman

Yeah, one cylinder may be running good, and the other may not.... doesn't mean you rule out the carb on them..... good job at finding the problem!