Kawasake 25HP - Increase Air Flow

My Great Dane 60" ZTR mowers has a Kawasaki 25 HP engine. I had wrapped white 3M Vetwrap around the air cleaner to catch trash before it got to the air cleaner. When I removed the air cleaner cover after mowing a few hours, I discovered that the cover restricted the air flow on the back side of the filter. I estimated that even with a new filter, the cover restricted about 25% of the air flow..

This material was snow white when I wrapped it around the filter. I had expected it to be completely dirty, but discovered that the air flow was completely blocked at the white area in the 2nd photo. In the 3rd photo, I took the cover off, turned it upside down, and placed the filter into the exact place it goes. This photo shows how the filter is pressed up against the back of the cover, cutting off the air flow in that area.

OK, you ask, "Why are you wrapping Vetwrap around the filter?". My son raced stock cars and did this to keep dirt and mud from stopping up his filter on a 350 cu.inch Chevy V8 and it worked beautifully. It also worked great on my mower. The problem seems to be that Kawasaki made the cover with 1/2" clearance between the filter and the cover, then put a 1/2" foam pre-filter over the filter, cutting off air to about 25% of filter.

I sliced off the back of the cover with a Dremel cutting wheel.

I then cut and spaced it back 1/2" with pieces of aluminum and pop rivets.

First photo shows before modification; 2nd shows after.

I pop riveted 1/2" pieces of black plastic into the spilt between the front & back of the cover and heated the small splits with a Weller soldering gun, melting them together. I Used black epoxy to smooth it up, ground it smooth, and sprayed on black primer.

OK, it doesn't look new, but mowing is about maintaining the equipment, not keeping mower in new condition. Right now I am waiting on a new blade belt clutch I ordered, so I had some time for this project. If you have an engine like this, you need to make sure the filter is not restricted.