The CB1100 Community Forum

Anyone remove the smog junk? The way the system works on the CB1100 is pretty much the same as they all do... I think it is called AIS or air induction system.

There is a vacuum switch which opens reed valves up on the front of the valve cover. The reed valves connect to the vacuum switch which is controlled by engine vacuum picked up from a smaller line from the carburetors. I think I saw another larger line going to the air box. What happens is that the reed valves open and crud is dumped down to in front of the exhaust ports and burned and anything that isn't burned is dumped into the air clear to be burned in combustion.

In general, the hole in the air box where the hose came in should be plugged (not that important I think) and the two reed valve snouts where the hoses connect need to be plugged so they are not open to the air in the event of a backfire and the vacuum fitting on the FI unit where the vacuum line came off needs to be capped.

The top of the engine is a mess the way it is with that plastic tray thing and all the electronics connected... once again Honda has done their best to confound but getting rid of the smog junk would be a step in the right direction. I don't think there is any electonic hooked to the system. Am I wrong?

(12-12-2015, 08:35 AM)wiredgeorge_imp Wrote: [ -> ]Anyone remove the smog junk? The way the system works on the CB1100 is pretty much the same as they all do... I think it is called AIS or air induction system.

There is a vacuum switch which opens reed valves up on the front of the valve cover. The reed valves connect to the vacuum switch which is controlled by engine vacuum picked up from a smaller line from the carburetors. I think I saw another larger line going to the air box. What happens is that the reed valves open and crud is dumped down to in front of the exhaust ports and burned and anything that isn't burned is dumped into the air clear to be burned in combustion.

In general, the hole in the air box where the hose came in should be plugged (not that important I think) and the two reed valve snouts where the hoses connect need to be plugged so they are not open to the air in the event of a backfire and the vacuum fitting on the FI unit where the vacuum line came off needs to be capped.

The top of the engine is a mess the way it is with that plastic tray thing and all the electronics connected... once again Honda has done their best to confound but getting rid of the smog junk would be a step in the right direction. I don't think there is any electonic hooked to the system. Am I wrong?

This is the only point you don't have quite right. You are probably thinking of the EGR system on older cars which recirculated exhaust gasses back into the carb. I believe that our bikes only have a PCV line to vent crank case fumes into the air box, but on a fresh engine, the worst these fumes usually contain is some oil vapor. This usually condenses and fills that tiny clear overflow tube at the front of the air box.

The PAIR system only injects clean filtered air just after the exhaust valves in order to help burn off volatiles downline in the exhaust system itself. The combination of the fresh, oxygenated air with unburnt noxious fumes and the heat of the exhaust creates small explosions often referred to as "decel popping". You normally don't hear that with a fully baffled stock exhaust, but you may start hearing it if you change to aftermarket.

Removing or blocking the PAIR system usually stops decel popping, but it doesn't usually affect performance in any way (other than helping your exhaust to run cooler). Removing it can make for cosmetic improvements on most bikes, but no-one currently makes any block-off plates for the reed valves on the CB1100.

Gumby, you've got it right. Just keeps your EPA happy by providing O2 to assist in burning any unburnt fuel etc. I've blocked mine as I didn't like the Staintune popping on decel. Of passing interest, and known by some on this forum, is that the OZ models have an IEV built into the OEM can. I also deactivated this when fitting the Staintune.

Cheers