I have had more than a few people PM me or ask me about how I went about doing my air box conversion. So alright, here we go, a basic how-to. I'm sure other bikes could scavenge this how-to, but it applies directly to my Honda Shadow ACE VT750. I did this mod almost a year and half ago as of this post, so the bike looks a bit different in the pics below. I can tell you that I have not had one problem with fitment nor performance at all. I do recommend that you also consider re-jetting your carbs to accommodate the increased air flow. That being said, my trial and error can be your benefit
All is done at your own cost and risk.... duh.
. 1 each of Edelbrock Pro Flo air cleaner p/n 1002. Holley makes an identical one and I assume one company makes it for the other. However, Advance Auto had the Edelbrock in my area.
. 2 each of appropriately sized stainless steel eye-bolts
. 2 each of tapered head bolts (thread diameter small enough for fitting through the eye of the eye-bolt and the stock air box attaching brackets to the cylinder head covers)
. 4 each of lock nuts (2 for attaching the Pro Flo assembly to the eye-bolts; 2 for attaching aluminum plate to the Pro-Flo backplate)
. Rivet gun (or smaller bolt/nuts for attaching aluminum plate to Pro-Flo backplate)
. Air-saw, hand shears, or similar for cutting aluminum
. Drill with assortment of metal bits
. Thin sheet of aluminum at least as big as the Pro Flo outer dimensions
. Gasket maker or exterior silicone
. Razor blade
. Cardboard or poster board
. Mechanics gloves (you're working with sharp edges)
( 1 ) - Remove the stock air intake cover, remove the air filter and the air box from the intake plenum under the tank.
( 2 ) - The stock air box has a (sort-of) triangle shaped intake tube. If you pull on it gently you'll notice that it's attached to the box with rubberized adhesive. Pull more and it will begin to lift and separate. Use a razor blade to assist cutting only the adhesive until completely removed.
( 3 ) - Place the triangle shaped intake tube you just cut off the stock air box back onto the intake plenum on the bike. Leave loose as you may need to reposition it up and down a bit in the following procedure(s).
( 4 ) - The Pro-Flo backplate has a huge beveled hole because it’s made for automotive carburetors. Using the air-saw, aluminum shears or other cutting device, cut out the circle around the beveled edges where it meets the flat surface of the back of the plate. The entire backplate surface should be able to lay flat if you do this correctly. As a side note: I chose to cut out this area so as to bring the air intake assembly closer to the bike. You 'could' choose otherwise, but then that would change the entire how-to. Here's the beveled area:
... The following steps 5 - 7 and part of 9 related to the cardboard template I did not do, but it may be easier for you and allow for errors to be corrected before finalizing; you decide ...
( 5 ) - Lay the Pro-Flo backplate on a piece of cardboard or poster board. Trace the overall outer edge and cut out your tracing from the cardboard. This will be used for your template prior to finalizing your modifications.
( 6 ) - Hold the cardboard template up to the bike against the triangle shaped intake tube. Position the template up and down so as to clear the fuel tank as best you can while lining up with the stock attachment brackets on the cylinder head covers. When you feel comfortable with the position, hold and trace the outer edge of the triangle shaped intake tube on the back side of the cardboard. Also mark the locations of the brackets, as you will be drilling holes into the new aluminum sheet you'll be using.
( 7 ) - Transfer the shape of the cardboard cut out to your aluminum sheet. Now trace the shape inward on the aluminum about 1/8 to 1/4 inch so as to come close to filling the entire inside of the Pro-Flo backplate.
( 8 ) - Attach the aluminum cut-out to the Pro-Flo backplate on the inside using rivets or small nuts and bolts (your choice). I recommend using a gasket making paste/cream or exterior silicone in-between the plates for better air flow properties. Shown here with step 9 completed and eye-bolts installed:
( 9 ) - On the cardboard, cut out the triangle shape you traced earlier. Place the cardboard on the back side of the Pro-Flo backplate aligning with the outer edges. Transfer the triangle shape to the Pro-Flo backplate. The top edge will more than likely run past your aluminum sheet onto the Pro-Flo backplate; that’s okay. Now trace inward about 1/8 – 1/4 inch. Cut out this inner shape. Be careful when you get to the top part as it gets a bit narrow and you could split the back of the Pro-Flo backplate (like I did; I had to use a piece of rigid wire pulled tight around two rivets to fix it). Not a big deal as it’s not seen when complete, but nevertheless a bit of a pit-fall. In any event, your piece should look very similar to the pics in step 8.
( 10 ) - Install the triangle shaped intake tube to the back of the Pro Flo plate. Simply push the split ends in and through so it grabs onto the aluminum. You may have to trim and shape the aluminum a bit but don’t go too much. Tighter is better and remember you can trim material, but it’ll be really hard to add it back. Test fit the assembly on the bike. You may have to move it up and down a bit on the intake plenum to clear the fuel tank. Shown here already installed on the bike:
( 11 ) - Once you’ve got it fitting correctly, now you’ll have to make the left and right attachments to the engine’s cylinder covers. Place each ‘eye’ of the eye bolts on top of the stock brackets on the cylinder covers, where the original air box attached to, then drop a beveled bolt through the top and loosely apply a lock nut from the bottom. Point the threaded ends of the eye bolts outward, perpendicular to the bike.
( 12 ) - Align the Pro-Flo backplate on the bike where it mounts. Hold this still and mark the back side where the threaded ends of the eye bolts will go through the back plate. Drill out those holes.
( 13 ) - Install the Pro-Flo backplate on the bike, ensuring the threaded ends of the eye bolts come through the two holes you drilled in the backing. Once installed, use the other two lock nuts to tighten the back plate to the bike. If you installed the triangular rubber piece on the bike first, now you’ll have to re-attach it to your Pro Flo. It works either way.
( 14 ) - Install the Pro Flo filter and cover and you’re done!
A few things to note … It’s not an exact science or perfect instruction that I’m giving you. Hopefully I covered it all correctly from my memory. By that I mean you’ll have to take your time and pay attention to what you’re doing to make certain things will line up. The first couple of times I ran into issues having the intake too high where it hit the fuel tank. The next time, it was too far out that the triangular rubber piece wouldn’t stay attached or would pop off occasionally. This is where a cardboard template might save you some errors. The cool part about this whole thing is that you can go back to your stock intake by simply re-adhering the intake piece back to the stock air box. And lastly, I don’t recommend running this intake in wet weather, or basically wet enough to saturate and cause gobs of water to enter the intake plenum. It would take a lot of water to get up in there, but I feel better informing you of this.
If you notice any errors/additions/omissions in my how-to, please don't hesitate to chime in! As well, if you've done this already and did something different please share!
Edited by Aced It, 27 March 2013 - 08:29 AM.