Carburettor Balancing by robB

• Philips screwdriver.
• 10mm socket.
• Socket ratchet.
• Socket extension bar.
• Clean rag.
• Balancing Gauges.
• Allen key 4mm

• No parts needed.

• Air (Hoover) pipes from top of tank cover - These should just pop off the cover other wise undo the jubilee clips and remove that way.
• Petrol tank top cover - 3 screws.

• Riders seat - 1 Allen bolt. Also the passenger seat
• Now remove the left side panel from the side of the bike by undoing the following screws shown in the picture below. There are also three screws to be undone under the passenger seat. Two holding the side panels together in the middle and a large one that attaches the panel to the sub-frame under the passenger seat. This makes removal of the fuel tap easier as it does not fit through the hole in the side panel when we come to remove it.

• At this point turn the fuel tap to the OFF position and run the engine for a few minutes, this will draw some of the fuel out of the pipe and prevent it splashing everywhere when you remove the pipe from the tap!

• Fuel tap knob – 1 Philips screw in the middle of knob. Ensure that the tap is switched to OFF first! Removing the tap will make removal of the tank a lot easier than trying to guide it out and scratching the frame.
• Petrol tank – 2 bolts under rider seat and another 2 at the front under where the tank top cover should be. See pictures. First remove the two bolts under the riders seat, and undo the two at the front of the tank slightly. With the two at the front loose you can pivot the tank upwards.
• Pull the right hand side panel out slightly to remove the lug from the tank.
• You should now be able to lift the back of the tank up and get access to the fuel pipe to remove it.
• Remove the fuel tap pipe by using a pair of pliers to undo the clip and pull it down the pipe slightly, then just twist and pull the pipe from the tap
• Finally remove the two remaining bolts at the front of the tank.

Now you have access to the air box it can be removed. Removal is as follows:

• Remove the 8 x 10mm bolts from the top of the air box (highlighted in yellow) see picture.
• Remove the large pipe on the right hand side by undoing the clip and twisting the pipe off.
• To help remove the two inner bolts (these have 2 rubber caps over them they will need to be removed first), dab the socket piece into some grease, when they finally come out they will not slip out of the socket.

You will notice that there are small ‘taps’ on the pipes beneath the gauges, these are to help damp the movement of the gauge needles as, when fully open the needles will flick around like anything. All you do is do the tap up and the needle movement will start to slow down. Do them to the point that the needles move but only a small amount, cutting the vacuum off will only cause the needles to get stuck and will not change when you are making the adjustments.
Make sure you have a fuel supply! As you can see I have turned the tank around and placed on a stool, other ways of doing this include using an old expansion tank with a pipe and a fuel tap and connecting to the fuel pipe. Just be careful whatever you do as petrol is flammable!
Start the bike and allow it to warm for about 5 minutes. If you are worried about overheating it should be fine so long as your cooling fan works. Otherwise use an indoor fan to keep the temperature down by allowing it to blow into the radiator.
Once warm, you are ready to start balancing your carbs. If you look at the picture below (picture CB5) you will see the front of the carbs and three screws which I have highlighted in yellow. These are the screws which we will adjust to balance the carbs!
Three screws you ask? When balancing, we start by bringing cylinders 1 and 2 to an equal vacuum, then cylinders 3 and 4 to an equal vacuum. This means that cylinders 1 and 2 must be made as equal as 3 and 4. It’s a little complicated to explain but follow the next lot of instructions and all will become clear!
You start synchronisation by adjusting the two outer screws. Lets start with cylinders 1 and 2, this will be your two gauges on the left, do not worry about the other two at this time. All you need to do is make these two gauges the same. (When balancing the reading that your are getting is irrelevant so long as the gauges are reading the same vacuum pressure). Do this by turning screw number 1 either way and, seeing what the needles do while doing this. Whichever way bring the needles closer to the same reading, keep on going until they are exactly the same. When they are reading the same congratulations you have just balanced two cylinders!
Now for the other two! Exactly the same as before except we are looking at cylinders 3 and 4 and the two gauges on the very right. Once again turn screw number 3 either way, whichever direction brings them closer together (cylinders 3 and 4 remember) so that they are giving the same reading. Once they are doing that, congratulations again, you have just balanced cylinders 3 and 4!
Now, you will probably notice that although cylinders 1 and 2 are the same and 3 and 4 are the same, cylinder 1 and 2 will have a different reading to 3 and 4. This is where screw number 2 comes in! All you do is turn screw number two either way, which ever way brings the whole lot to the same reading. I tend to do this by looking at just gauges for cylinder 2 and 3 as they are next to each other on your gauges, when gauges 2 and 3 are reading the same, the rest of your carbs should also be reading the same! And for the third time, congratulations, you have just balanced the carbs on your ZXR!!!! Wasn’t that hard was it???

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