The carb installation is the toughest part to install. With that said, it is not really that tough. It may require a little patience and knowledge on the part of the installer. If you feel like this is not something you can do, please enlist the help of a buddy or a mechanic that is familiar with small engines, two strokes, or dirt bikes.

First of all the carb comes with a jet that is separate in the box. This will need to be swapped for the one that comes installed. These are standard size Mikuni jets (actual dimensions match, but numbers do not) so you should be able to find one, if need be, at your local dirt bike shop. About 99% of our customers use the enclosed jet and have no need to find any other jetting. Just remove the plug at the base of the bowl and then replace the jet that is directly under it with the one provided.

Throttle Cable
The major pain for the Yamaha installs is the factory pull-pull throttle cable system. If you have another brand bike, you can skip this section as everything else has a single pull cable just like the one for this carb, and you may be able to use the stock cabling.

The Vino and Zuma kit does not come with a cable, but you can get one at a local bike shop. Just ask for the longest rear brake cable they have (we have used a tandem bike rear brake cable on several installs). The pull-open cable from the stock setup will need to be removed and replaced by the cable provided or bought. Clip the lead barrel off the carb end of the cable and remove it through the throttle handle end. If you are using a bike rear brake cable, you will need to remove a plastic sleeve that is located in the 90 degree angle at the top after the cable comes out of the throttle handle. If you do not remove the pastic sleeve, the handle may not retract autonomously, which could lead to the throttle sticking. So unless you like cruise control, remove it. You do not need to remove it when using the cable provided for the non-Zuma kits.

When installing the cable, it is always a good idea to lubricate the cable as you insert it in to the housing. You can use just about anything, motor oil, grease, silicone lube, and they also sell special cable lubricant. Once installed replace the throttle handle and assembly at the handlebar and move to the carb end. Do not remove the steel bracket where the two stock cables terminate. This will mate up to the 90 degree angle elbow tube that is provided with the carb (see picture below).

With the cable routed through the carb elbow, slide cap, slide cap gasket, slide plate and slide (you do not need to put the spring in yet as you can thread it on after), either tie a knot in the end with some pliers (needle nose work best) or solder a barrel on the end. I have also used a smaller pinch bolt that may be available at your local hobby shop (used on the Traxxis T-Maxx RC monster truck throttle linkage). With the carb put together move to the return cable.

On the stock return cable, clip the lead barrel and install a pinch bolt. This will provide some adjustment for the carb slide in case the knot or solder used is a little off. This actually provides quite a bit of leeway for adjustment for when the slide opens as it acts against the pull-open cable. It also provides a means of preventing the throttle handle from rolling forward. (note: sometimes you can leave the barrel on the cable, but it may cause the handle to be in the wrong position when returned (closed throttle position) and could cause excessive wear on the top of the cable.)

Carb Install
Once the cables are all hooked up and adjusted, install it to the rubber intake manifold and attach the fuel line, vacuum actuated fuel switch line and the oil line as well as the auto choke assembly (the wires will need to be clipped and attached to the wires from the stock choke wires as the plugs do not match, the order is not important as it is just a closed or open circuit and polarity is not an issue). Also the clip in the zip lock bag with the jet etc. is to secure the auto choke in place. Just install it into the grooves on either side of the choke. If the choke is all the way down where it should be the clip will lock into place.

Troubleshooting and Tuning
Now that the carb is installed with the cabling hooked up, you are ready for some tuning. Usually it is just install and go, but sometimes it is necessary for a little fine tuning.

The carb components work in this manner: the pilot or idle jet is used from 0-1/3 throttle, the slide needle actuates from 1/3 to 2/3 throttle, and the main jet is responsible for 2/3 to wide open throttle (WOT).

The best way to tune is to read the spark plug, it is your companion on the air/fuel mixture. A chocolate brown is the preferred color. See "Tuning HowTo" for more info.

If you have a hesitation when “flooring it” from an idle, you may need to adjust the idle mixture screw in. Turn it in a half a turn at a time while running, and check for the symptoms in between. If you make a mistake or turn it too much one way or the other, turn it all the way in, the back it out 2 1/2 turns. Be careful not to turn it out too much or the screw can fall out due to vibration.

If there is bogging in acceleration you may want to drop the slide needle down. This actually means moving the clip on the slide needle up (the clip holds the needle from the top, so moving the clip up effectively drops the needle down lower into the carb).

Make sure that you do not confuse tuning the carb with tuning the transmission. The bike should, when the transmission is tuned correctly, rev as high as possible before the clutch stalls and during acceleration so as to get the best power. Remember, the higher the revs, the more power and the faster your bike will go. If the bike starts moving before the motor is in powerband (the range in which the motor makes the most power) it will seem to bog, but really it is just running too slow and is not getting into powerband. A dead giveaway that your transmission is not tuned correctly is that the bike is slow to 30mph, then it takes off. For more information on tuning the variator and transmission, see the instructions on the Tecnomoto variator.