AIS Removal

AIS (Air Injection System)

The AIS injects air into the exhaust chambers as a means of burning excess fuel when the bike is decelerating. When fitting less restrictive pipes (slip-ons or full systems), the AIS can possibly contribute to excessive backfire on deceleration because these will cause a lean condition at idle. There may be other causes of the popping on deceleration especially once you have added freer flowing exhaust - the idle may need to be raised, the carbs synched, and the PMS properly adjusted.

Before you do the AIS plug or removal because somebody told you it would stop your backfire, make sure you have the bike tuned, and then decide. Generally speaking, a simple PMS adjustment of 1/4 to 1/2 turn on each carb will eliminate the backfire issue without AIS removal.

Reasons for removing the AIS

WARNING: DO NOT Remove or Plug the AIS system with bikes having catalytic converters still installed -- 05 Calif. and all 06 and later bikes.

They are still installed if you have the stock tail pieces of the OEM exhaust still installed. They are NOT "still installed" if you put on either slip-ons or a full after-market exhaust system!!!!

Catalytic converters are designed to clean up exhaust emissions by burning off any residual unburned hydrocarbons. In the process they become extremely hot. If there is a large amount of unburned fuel passing into the Cats, they will get hot enough to potentially cause anything flammable near them to catch fire. The AIS system allows oxygen rich air into the exhaust system at the outlet port in the cylinder head. This oxygen will support combustion of any unburnt gasses and consume the hydrocarbons before they make it to the Cats, thus helping to keep the temperature in the Cats down. Disabling the AIS and keeping the Cats is high risk for a fire.

Cat equipped bikes also have fuel cutoff solenoids in the carb float bowls. The purpose of the solenoid is to cut off the fuel supply a few hundred RPM prior to hitting the REV limiter. This is done so that a heavy shot of unburned fuel does not make its way into the Cats when the REV limiter cuts off ignition to 1 cylinder. By the time the REV limiter is activated, there is no fuel left in the main jet circuit to burn. In fact the REV limiter on a Cat equipped bike is several hundred RPM higher than the limiter on a non-Cat bike but the engine will run out of fuel at about the same RPM as a non-Cat bike, so if everything is working as it should, a Cat equipped bike will not actually hit the REV limiter. This is why people who have installed POD intake kits and modified the float bowls and solenoids are reporting a higher REV limit than the older bikes.

These components are designed to work as a team to clean up exhaust emissions, they should not be modified piecemeal. In order to remove the AIS and/or the solenoids it is prudent to also remove the Cats. - Thanks to Daryl - WhiteStar246

AIS Removal / Plugging

Below are 2 different step by step procedure documents to help make the job easier.

AIS Removal Step By Step Procedures I thanks John Klopfenstein

AIS Removal Step By Step Procedures II thanks to JStar2 and Corsair

The preferred method is to completely remove all AIS components. With the partial disable, moisture will accumulate in the metal pipes and they will rust out.

This will cause a leak, usually discovered by finding rust spots on the left side crank case below the AIS tubing. If you're going to do the job, do it right and remove everything.

Spent .45 ACP shell casings are the preferred "plug" to use in the heads. Just tap them in gently. No glue or sealant is needed. The solid plugs available from different vendors will also work, but you have to be careful that you don't crack the head installing them. If you can find the shell casings, they are cheaper, safer and easier to install.

AIS Plugs and Elbow Replacement

The basic technique for removing the elbows are use vise grips with a combination of rotation and pulling. Pick up a can of "Canned Air" like they use for cleaning computer equipment. Turned upside down the spray will come out freezing cold. Use this to "freeze" the elbows, then begin to twist them back and forth until they work free. You may need to re-freeze them a couple of times. You can also use a slide hammer with a hook attachment or Vice Grip attachment to pull the elbows free.

You can also install 1/4" Allen bolts with "glue" into the elbows as noted in the article to plug the holes in each cylinder. There are hot exhaust gasses exposed to the elbow, so you may run into an issue where the "glue" burns out causing an immediate exhaust leak. This is why the method above is preferred.

AIS Removal thread on the Forum: Comments and links to other comments

V STAR 1100 Riders Forum