Like many others, I am reluctant to take the gas tank and airbox off unnecessarily, because it takes a fair bit of time and because the fuel fittings are, as Jesse Norton has pointed out, fragile and too easy to damage if you move them around just a little bit quickly or carelessly, or forget to put lift blocks under the fuel tank when you place it on a surface while you work on the bike.
So, I was pleased to find that, at least on the Z400, you can disable and remove MOST of the AIS system without having to take off the tank and airbox.
Here are the steps (sorry, no photos):
- Remove the RH long body panel (3 bolts, 3 pushpins, and a couple of friction fit pins that you just pull on to remove). Note that one bolt is longer than the other 2. It goes into the threaded hole on TOP where this body panel attaches to the "dashboard" piece.
- Remove the small triangular body panel that covers the end of the radiator assembly (3 bolts).
- Pull the AIS-to-airbox hose off the airbox by removing the retainer clip (by squeezing its ears with pliers) and sliding the hose off the airbox spigot. Once the clip is off the hose, just use a WIDE screwdriver (to distribute the load across a wider portion of the hose end) to pull the hose off the spigot.
- Pull the same hose off the AIS valve by removing the retainer clip and sliding the hose off of the AIS valve. Same technique as above.
- The AIS valve is enclosed inside a rubber sleeve. Peel that sleeve off by hand carefully. You need to get it off so that the AIS valve then becomes small enough to slide out of the frame, while still attached to its electrical connector. You can't really disconnect that electrical connector without getting the AIS valve somewhat outside the frame so you can see and reach the disconnect clip.
- There is plenty of slack wire to enable pulling the AIS valve slightly outward and to orient it so that the connector becomes easy to disconnect. Once you have oriented the connector into the right position, press down on the 2 little wings on the blue connector while simultaneously pulling the connector off the AIS valve. If you are doing this correctly, it comes off easily and without being damaged. If it won't move, don't force it!! Get help.
- Once you have the electrical connector disconnected, you can place it temporarily out of harm's way (there is lots of wire to do that)
- Now remove the clip that holds the AIS-to-engine hose to the AIS valve. Then pull the AIS valve off the hose. Leave the hose attached to the engine. (It is not possible to easily get that hose off without removing the fuel tank, PLUS even if you do, how are you going to plug the spigot hole in the engine-mounted plate??
- Buy 4 items at your local auto parts store (I went to NAPA, who had what I needed):
1. A "vacuum cap" size 1/2" (ID)
2. A vacuum cap size 3/4" (ID)
3. permatex gasket sealant
4. A brass "cap" that is a light interference fit into the end of the airbox-to-AIS-valve hose. W are not going to reinstall that hose, but we are using it to get the right size of brass cap to plug the engine-to-AIS hose. Make sure you get the brass cap size that is a LIGHT interference fit, not a hard interference fit, or a completely loose fit.
This is important because, per Kawasaki Brad, the Engine-to-AIS hose is subject to BOTH vacuum pulses and pressure pulses as the engine operates. If the fit is too loose, the brass cap can be blown out, which would be disastrous. Apparently, on some ZX-10s, there was a Kawasaki recall, as the AIS valve sometimes opened when it should not, and allowed hot gases to reach the airbox and STARTED A FIRE. So, we want an interference fit.
We also do not want a hard interference fit, simply because we cannot apply enough force to push the brass cap into the hose because we can't get our fingers or a tool past the frame members, wiring, and cables that are in the area, to apply enough force!
- Next, coat the thread of the brass cap with Permatex, generously. Then, using a pair of LONG pliers to hold the brass cap, push the brass cap into the end of the engine-to-AIS hose. The brass cap's head will rest on the end of the hose while its thread and the Permatex engage the iD of the hose.
- Next, use the long pliers to start the 3/4" ID vacuum cap onto the engine-hose/brass cap assembly. This 3/4" vacuum cap is merely "extra insurance" against the brass cap being blown out by a strong pressure pulse. The further you can push the vacuum cap onto the hose, the better it will help ensure that the brass cap is firmly trapped inside the hose, to resist any pressure pulses.
- Finally, plug a suitable resistor into the blue AIS wiring connection on the bike, to "simulate" the AIS valve. Kiwi Rider has identified one resistor configuration that apparently works. I bought Kawasaki Brad's GIANT resistor, which he sized to ensure that it will not be blown out by the bike's electrical signal to the AIS. Brad's resistor is quite LONG, but is easily fastened alongside a frame member to be secured out of the way of any harm. It ensures that the absence of the AIS will not trigger a check engine light.
I did this installation myself, and I am NOT a qualified mechanic, and I have larger than average hands, so if I could do it, you probably can too if you are somewhat comfortable with doing mechanical stuff.
I also tested this setup for about a half hour, riding at different rpm, loads, and gears, and experienced no CEL and no issues of any sort. BUT, as always, I do not personally guarantee that this mod will work for you or anyone else. If I do see any issues come up as I accumulate miles with this setup, I will post here about them.
There are multiple reasons for doing this mod:
1. It greatly reduces the odds of your getting backfires or pops in the exhaust, especially if you reflash the ECU
2. Disabling the AIS function is the only way to prevent corruption of your true air-fuel-ratio when doing dyno tuning or testing, or on-the-road AFR tuning
3. It takes approximately 0.4 lb of weight off the motorcycle. If you, like me, value the high power to weight ratio that the Z400/Ninja 400 can deliver, this helps as part of a larger weight reduction program (it is practical to get at least 18 to 20 lb of weight off of a Z400 / Ninja 400 without going crazy on costs, effort, and difficulty).
Jim G
So, I was pleased to find that, at least on the Z400, you can disable and remove MOST of the AIS system without having to take off the tank and airbox.
Here are the steps (sorry, no photos):
- Remove the RH long body panel (3 bolts, 3 pushpins, and a couple of friction fit pins that you just pull on to remove). Note that one bolt is longer than the other 2. It goes into the threaded hole on TOP where this body panel attaches to the "dashboard" piece.
- Remove the small triangular body panel that covers the end of the radiator assembly (3 bolts).
- Pull the AIS-to-airbox hose off the airbox by removing the retainer clip (by squeezing its ears with pliers) and sliding the hose off the airbox spigot. Once the clip is off the hose, just use a WIDE screwdriver (to distribute the load across a wider portion of the hose end) to pull the hose off the spigot.
- Pull the same hose off the AIS valve by removing the retainer clip and sliding the hose off of the AIS valve. Same technique as above.
- The AIS valve is enclosed inside a rubber sleeve. Peel that sleeve off by hand carefully. You need to get it off so that the AIS valve then becomes small enough to slide out of the frame, while still attached to its electrical connector. You can't really disconnect that electrical connector without getting the AIS valve somewhat outside the frame so you can see and reach the disconnect clip.
- There is plenty of slack wire to enable pulling the AIS valve slightly outward and to orient it so that the connector becomes easy to disconnect. Once you have oriented the connector into the right position, press down on the 2 little wings on the blue connector while simultaneously pulling the connector off the AIS valve. If you are doing this correctly, it comes off easily and without being damaged. If it won't move, don't force it!! Get help.
- Once you have the electrical connector disconnected, you can place it temporarily out of harm's way (there is lots of wire to do that)
- Now remove the clip that holds the AIS-to-engine hose to the AIS valve. Then pull the AIS valve off the hose. Leave the hose attached to the engine. (It is not possible to easily get that hose off without removing the fuel tank, PLUS even if you do, how are you going to plug the spigot hole in the engine-mounted plate??
- Buy 4 items at your local auto parts store (I went to NAPA, who had what I needed):
1. A "vacuum cap" size 1/2" (ID)
2. A vacuum cap size 3/4" (ID)
3. permatex gasket sealant
4. A brass "cap" that is a light interference fit into the end of the airbox-to-AIS-valve hose. W are not going to reinstall that hose, but we are using it to get the right size of brass cap to plug the engine-to-AIS hose. Make sure you get the brass cap size that is a LIGHT interference fit, not a hard interference fit, or a completely loose fit.
This is important because, per Kawasaki Brad, the Engine-to-AIS hose is subject to BOTH vacuum pulses and pressure pulses as the engine operates. If the fit is too loose, the brass cap can be blown out, which would be disastrous. Apparently, on some ZX-10s, there was a Kawasaki recall, as the AIS valve sometimes opened when it should not, and allowed hot gases to reach the airbox and STARTED A FIRE. So, we want an interference fit.
We also do not want a hard interference fit, simply because we cannot apply enough force to push the brass cap into the hose because we can't get our fingers or a tool past the frame members, wiring, and cables that are in the area, to apply enough force!
- Next, coat the thread of the brass cap with Permatex, generously. Then, using a pair of LONG pliers to hold the brass cap, push the brass cap into the end of the engine-to-AIS hose. The brass cap's head will rest on the end of the hose while its thread and the Permatex engage the iD of the hose.
- Next, use the long pliers to start the 3/4" ID vacuum cap onto the engine-hose/brass cap assembly. This 3/4" vacuum cap is merely "extra insurance" against the brass cap being blown out by a strong pressure pulse. The further you can push the vacuum cap onto the hose, the better it will help ensure that the brass cap is firmly trapped inside the hose, to resist any pressure pulses.
- Finally, plug a suitable resistor into the blue AIS wiring connection on the bike, to "simulate" the AIS valve. Kiwi Rider has identified one resistor configuration that apparently works. I bought Kawasaki Brad's GIANT resistor, which he sized to ensure that it will not be blown out by the bike's electrical signal to the AIS. Brad's resistor is quite LONG, but is easily fastened alongside a frame member to be secured out of the way of any harm. It ensures that the absence of the AIS will not trigger a check engine light.
I did this installation myself, and I am NOT a qualified mechanic, and I have larger than average hands, so if I could do it, you probably can too if you are somewhat comfortable with doing mechanical stuff.
I also tested this setup for about a half hour, riding at different rpm, loads, and gears, and experienced no CEL and no issues of any sort. BUT, as always, I do not personally guarantee that this mod will work for you or anyone else. If I do see any issues come up as I accumulate miles with this setup, I will post here about them.
There are multiple reasons for doing this mod:
1. It greatly reduces the odds of your getting backfires or pops in the exhaust, especially if you reflash the ECU
2. Disabling the AIS function is the only way to prevent corruption of your true air-fuel-ratio when doing dyno tuning or testing, or on-the-road AFR tuning
3. It takes approximately 0.4 lb of weight off the motorcycle. If you, like me, value the high power to weight ratio that the Z400/Ninja 400 can deliver, this helps as part of a larger weight reduction program (it is practical to get at least 18 to 20 lb of weight off of a Z400 / Ninja 400 without going crazy on costs, effort, and difficulty).
Jim G
