How to remove the emissions systems and install a block off plate on the Yamaha R3 / MT-03

This post will cover how to remove the air injection system and charcoal canister from the Yamaha R3 using my removal kit with blockoff plate.

If you will be tuning the Yamaha R3 using an O2 sensor, you will have to bypass or remove the clean air injection system first in order to get proper AFR readings.  This is the system that injects clean air from the airbox into the exhaust ports to help burn excess fuel and lower emissions.

I will also cover removal of the closed loop vent system and charcoal canister to drop weight on race bikes.  This system connects a closed loop from the fuel tank vent, through a charcoal canister, then back into the throttle bodies to prevent evaporated fuel from entering the atmosphere.

*NOTE*  This charcoal canister system has no negative effect on street bikes, and there is no reason to remove it.  Please help reduce pollution and only remove this system from race bikes.

Removing all of this extra crap for racing drops about 2 lbs, although you add a few ounces back with the new block off plate.

 

The air injection system and block off plate install can be done by only removing the fuel tank, but it is easiest to do everything with the side fairings and fuel tank off the bike.  I’m assuming if you are building a race bike, you have already removed the fairings, but if not, follow the step by step directions here to remove the side fairings:

How to remove the side fairings from the Yamaha R3

And follow the step by step directions here to remove the fuel tank:

How to remove the gas tank from the Yamaha R3

Once you have the bike naked, the charcoal canister and air injection systems are easy to access and remove.  Here are some pictures so you can identify everything I will be talking about.  When you lift off the fuel tank, you will be left with 2 hoses.  The smaller hose runs down the side of the engine and connects to the charcoal canister (marked in blue) and the larger hose is the overfill drain (marked in red) and runs down the other side of the bike and drains out the bottom.  You can follow the vent hose (blue) down to the charcoal canister, and you’ll see another hose (green) that runs out of the charcoal canister and splits into both throttle bodies.  The hose in purple is the air injection system and connects from the air box to the air pump and plugs into the port on the exhaust manifold (purple).

 

 

Air Injection System Removal and Smog Block Off Plate Install

Tools Needed:
Some pliers to help get all the hose clamps off
5mm allen wrench
Phillips head screwdriver
a small pick or flat blade screwdriver to release some clips and pry out connectors
YamahaR3Racing.com smog block off kit

Step 1:  Locate the hose coming out of the air box (purple).  Squeeze the hose clamp and pull the hose off the port on the air box.  Cap this port with our supplied 1/2″ rubber vacuum cap and reuse the stock hose clamp.  If you don’t have a 1/2″ vacuum cap, you can cut a short length of the hose, fold it back on itself, and zip tie it to seal the port.  Please note, I posted pictures of both methods, you will only use one method 🙂

  

 

Step 2:  Unplug the connector from the pump and zip tie off to something to secure it, you won’t be using it for anything.  Pull the air pump free from the tabs and pull the hose off the plate on the exhaust port and remove the hoses and pump from the bike.

 

Step 3:  Use a 5mm allen wrench to remove the 2 bolts in the exhaust port cover and remove the cover.  Then use a small pick or flat blade screwdriver to press through one of the reed valves and pry the valve assembly out.  Don’t try to pry the assembly out from the edge, you may damage the gasket.  Remove the two baskets located under the valves.  DO NOT DAMAGE THE GASKET!!!  YOU HAVE TO REUSE IT!!!

 

Step 4:  Use a Phillips screwdriver to take the reed valves out of the gasket block.  Then place the gasket block back into the exhaust port with the small boss in the corner to the front left side of the motorcycle.

 

Step 5:  Place the block off plate over the gasket so the cutout in the back corner of the block off plate goes over the little boss sticking up out of the gasket block, then tighten the bolts.  That’s it, you’re done!

 

 

Charcoal Canister and Vent Hose Removal

Tools Needed:
Some pliers to help get all the hose clamps off
8mm socket
10mm socket
a small pick or flat blade screwdriver to release some clips and pry out connectors

 

Step 1:  The first step is to remove the hose that has a T split and goes to both throttle bodies and cap off the 2 ports on the throttle bodies with the two 3/16″ vacuum caps supplied in my kit and reusing the 2 OEM clamps.  However, if you don’t have vacuum caps, it’s easier to only remove part of this hose and just fold and zip tie the hose to cap it off.  So the first four pictures are for removing the hose and installing vacuum caps, the last two pics show the hose capped off at the T split with a zip tie.  You could also make your own vacuum caps by cutting 2 small pieces of hose, folding them over, and zip tying them in half.

If you don’t have vacuum caps, cut off the hose as seen in this picture, fold it back and zip tie it to seal off the line.

 

Step 2:  Use a 10mm socket to remove the bolt securing the hoses at the top of the canister, and an 8mm socket to remove the two bolts securing the canister to the front of the motor, and remove the canister and attached hoses from the bike.

 

The last steps are sort of personal preference.  I prefer to just leave the vent on the bottom of the gas tank open, I see no advantage to routing it somewhere else.  The overflow drain currently runs down under the bike (hose marked in red).  I chose to shorten mine and just route it through the existing clip on the side of the bike and remove half the hose.  You can safely remove this hose altogether if you don’t care about overflow gas pouring on top of the engine, or you can leave it routed under the bike so overflow gas flows out the bottom into your belly pan.