Air Filter Replacement
I'm sure this will be about as interesting as watching paint dry. I had Craftsman riding mowers for years, but they just weren't built for the rough terrain I've had to cut. Everytime I needed to cut the grass, something had to be fixed first. Usually it was one of the 90" long belts that lasted about two cuts. Several years ago, fed up with the constant maintenance, I bought a Scag Tiger Cub zero turn mower. It was a wise choice. It cuts beautifully, easy to maintain, super-heavy duty...only one little defect, though.
The air filter clogs up too easily. The design of the Kawasaki 19 hp engine has a tendency to suck dirt up from behind the mower deck and deliver it to the carburetor. On later models, they changed the air filter design and offered a remote air filter for retro-fit to older models. One little draw back...they wanted well over $300.00 for the kit. While replacing the engine would cost alot more than that, I knew I could do it more economically. The trick was to find the time to do the work. So, the other day the engine was running poorly because of a clogged air filter and I went to NAPA to buy a new filter. 20 BUCKS! And it'll clog up after one cutting. I bought it and decided it was time to make my own.
Some time back I saw that Surplus Center had some canister type air filters for sale. I think they were around $20.00, but I don't really remember, anyway I bought a couple of them. I also needed some bent tubing of the same diameter which I just happened to have. It came from Summit Racing for some other project (I don't remember which one) and cost $16.00.
This is what the new NAPA filter looked like after one use. If all the dirt was on the outside, that would be okay, but unfortunately it seemed to always bypass the filter.
Over time, this stuff will kill an engine. Look how dirty it is down at the venturi. Below is what the intake should look like.
The air filter that I wanted to use is a canister type and quite large in comparison to the existing filter element. Of course it has much more surface area and a housing to catch dust.
I decided to mount it directly over the engine and put braces down to the mower frame. This should reduce vibration somewhat. I think it will need some extra bracing, but for now I decided to use 1" x 1" x 1/8" angle and just weld the housing directly to the angle. I had drilled holes in the angle legs where they would mount to existing bolts on the frame.
Once I located the filter, I placed the bent pipe on the carburetor intake to determine the angle. I marked where I would slot it.
I cut it along the marks and then welded it to a 1/4" flange I had made to fit the carburetor intake. I should have shaped the flange like the intake opening, but the stock air filter had an oblong slot and didn't compensate for the extra area, so I figured it wouldn't be any worse than from the factory.
I never claimed to be a machinist, so sometimes my parts don't look factory-made. I also had to cut the bent tube at the 90º point and weld on a 1" piece to attach a hose. Anyway, I didn't take a photo of the welded up tube, but I also added two standoffs so the engine cover would still fit and capped the end of the tube. Below is the finished intake.
I ground my welds since I have some expert welders in my family and didn't want to offend them with my earthworm welds. I cut a piece of heavy rubber for the gasket and then used a piece of foam on top to make sure I had a good seal. I painted everything and mounted the filter over the engine. I connected the filter to the intake pipe with a 2" OD x 12" hose I purchased at NAPA for $12.00. The finished product is below.
Hopefully this investment of about $50.00 will save me much more and make the engine last a lot longer. Normally when I do something like this, I can't wait to try it. But, hey...it's a lawn mower. I definitely CAN wait to try it. Unfortunately I've got several acres of grass calling my name right now.
The air filter clogs up too easily. The design of the Kawasaki 19 hp engine has a tendency to suck dirt up from behind the mower deck and deliver it to the carburetor. On later models, they changed the air filter design and offered a remote air filter for retro-fit to older models. One little draw back...they wanted well over $300.00 for the kit. While replacing the engine would cost alot more than that, I knew I could do it more economically. The trick was to find the time to do the work. So, the other day the engine was running poorly because of a clogged air filter and I went to NAPA to buy a new filter. 20 BUCKS! And it'll clog up after one cutting. I bought it and decided it was time to make my own.
Some time back I saw that Surplus Center had some canister type air filters for sale. I think they were around $20.00, but I don't really remember, anyway I bought a couple of them. I also needed some bent tubing of the same diameter which I just happened to have. It came from Summit Racing for some other project (I don't remember which one) and cost $16.00.
This is what the new NAPA filter looked like after one use. If all the dirt was on the outside, that would be okay, but unfortunately it seemed to always bypass the filter.
Over time, this stuff will kill an engine. Look how dirty it is down at the venturi. Below is what the intake should look like.
The air filter that I wanted to use is a canister type and quite large in comparison to the existing filter element. Of course it has much more surface area and a housing to catch dust.
I decided to mount it directly over the engine and put braces down to the mower frame. This should reduce vibration somewhat. I think it will need some extra bracing, but for now I decided to use 1" x 1" x 1/8" angle and just weld the housing directly to the angle. I had drilled holes in the angle legs where they would mount to existing bolts on the frame.
Once I located the filter, I placed the bent pipe on the carburetor intake to determine the angle. I marked where I would slot it.
I cut it along the marks and then welded it to a 1/4" flange I had made to fit the carburetor intake. I should have shaped the flange like the intake opening, but the stock air filter had an oblong slot and didn't compensate for the extra area, so I figured it wouldn't be any worse than from the factory.
I never claimed to be a machinist, so sometimes my parts don't look factory-made. I also had to cut the bent tube at the 90º point and weld on a 1" piece to attach a hose. Anyway, I didn't take a photo of the welded up tube, but I also added two standoffs so the engine cover would still fit and capped the end of the tube. Below is the finished intake.
I ground my welds since I have some expert welders in my family and didn't want to offend them with my earthworm welds. I cut a piece of heavy rubber for the gasket and then used a piece of foam on top to make sure I had a good seal. I painted everything and mounted the filter over the engine. I connected the filter to the intake pipe with a 2" OD x 12" hose I purchased at NAPA for $12.00. The finished product is below.
Hopefully this investment of about $50.00 will save me much more and make the engine last a lot longer. Normally when I do something like this, I can't wait to try it. But, hey...it's a lawn mower. I definitely CAN wait to try it. Unfortunately I've got several acres of grass calling my name right now.
Thanks for the Surplus link. I've been looking to order a new filter for a couple of weeks. I've been having the same problem with mine clogging up to quickly.
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