Friday, October 19, 2018

Vapor Recovery and AIS Removal

When I purchased the KLR650 in November 2015, I was rather surprised...indeed shocked...when I noticed it was a California Model. I mean, over here on the right coast, we don't normally even think that a dealer would have a Cali Production Model on the showroom floor. Anyway, I had a seat rip problem that caused me to remove the seat and there is was, plain as day, the charcoal canister and the dual vent ports of the Cali Model Vapor Recovery System. How can that be?

Of course I was all over my dealer, who didn't know how that happened except to say that the manufactures may from time to time sneak a Cali model in the shipment. However, after a day or two the real reason came to light...for at least the 2016 Model Production Year all Camo Models were Cali Models. There you go...

Well, here I am over 13,000 miles later dealing with a major top end overhaul (twice now under the valve cover) and I'm thinking all this pile of intertwined hoses and useless components needs to go...and there is no better time than right now to tackle the modifications.

There are two systems that I need to tackle.

First is the California Vapor Recovery System Removal.

Second is the Air Induction System (AIS).

Let's start with my removal of the Vapor Recovery System (VRS). In fact this system, properly working, doesn't do any harm to the bike or affect it's performance. However, it doesn't to any good from a performance perspective either. What one is left with is a convoluted maze of components and hoses that simply get in the way of just about everything that needs to be done on the motorcycle. Further, it's been noted some KLRistas in the KLR Forums and AdventureRider that a non-working VRS system can cause problems out on the trails and a good idea for a rally bike.

Anyway, here is a diagram of the Vapor Recovery System as reflected in the KLR650 Service Manual that I tinkered with to better understand the flow, so to speak. I have laid in the color coding (for further reference) and the Carb overlay (to help show that connection). The principal components of the VRS are the Rectangular Charcoal Canister and tube-like the Vacuum Pump (aka Separator). The trick, as I saw it, was to modify the hose structure to be able to remove those two components.

Fuel Tank:

One of the many distinguishing features of the Cali VRS is the dual fuel tank nipples. They are color distinguished on the tank with a red button (right line) and a blue button (left line). The colorized red hose, representing the red/right valve, is vacuum line of the VRS. The colorized "dark" blue hose, representing the blue/left valve, is the traditional tank vent line. For purposes of this operation, the red/right must be removed from the Vacuum Pump and capped off. Probably the best means of capping off hoses is to use Dorman-Type Vacuum Caps (as shown below) available at auto-part stores. The old skool stick a bolt in the hose with a hose clamp will probably work too.

The "dark" blue hose in the diagram above continues to serve to vent the tank to the atmosphere. That hose is disconnected from the Vacuum Pump and secured to a location that will have it out of the way.

Air Box/Canister:

The air box is connected to the Charcoal Canister via the green hose. The green hose is no longer necessary. However, the air box is going to be left with a hole in it, and that hole is on the wrong side of the air filter. The hose either needs to be capped or the hole needs to be properly filled.

The Canister is then connected to the Vacuum Pump by the "light" blue hose. That hose can be removed. The hose on the front of the Canister vents to the atmosphere and, like the "light" blue hose is no longer needed.


The Orange hose connects the Vacuum Pump to the carburetor via a T-Conduit. This hose is the "vacuum" line that also serves the petcock. As a result, the modification must continue to support the petcock. The best method is to replace the T-Conduit and run a single hose from the petcock to the nipple on the carburetor.

At this point, the Vacuum Pump and Canisters are no longer connected and can be removed along with their respective brackets.


The next system that I eliminated is the Air Induction System (AIS). The AIS is not part of the Cali Evaporative Recovery System, but it is part of the 50 State Emissions. It's purpose is to impart fresh air into the exhaust pipe to burn excess fuels. However, it becomes ineffective when aftermarket pipes are installed, such as the Yoshi on my KLR.

The primary components of the AIS are the Air Valve and the notorious Cylinder Head Pipe that is affixed directly in front of the spark plug.

The air valve receives clean air from a hose connecting from the back of the valve to an aperture into the frame directly below the fuel tank. When a vacuum is created by a vacuum tube to the carburetor, air is moved into the cylinder head and ported to the header pipe so fuel can be burned off.

A special kit available by Eagle Mike is necessary to do this modification (about $15). The kit provides a very simple block-off cap for the cylinder head and a nipple cap for the carburetor.

In the diagram for the VRS, above, I noted the carburetor nipple that supports the vacuum tube of the AIS. It's bronze in color and fairly obvious as shown in the photo below. That is the nipple that is capped with the orange vacuum cap in the EM Kit.

When the cylinder head block-off plate and the vacuum cap on the carburetor nipple are installed all other components of the AIS (Air Valve and Hoses) can be removed. It would be a good idea to keep these particular parts tucked away in case we go back to the stock exhaust pipe.

At least we got a little weight loss. Here's all the junk that came off on the scale...

No comments:

Post a Comment