Throttle Kit InstallationJan 1, 2008
You've been riding your ATV all day, and now it feels like your thumb is going to fall off. The workout you get from a thumb throttle might be an asset of you are a professional hitchhiker or a thumb wrestler, but for the rest of us?
Thumb throttles were part of the deal made with ATV manufacturers and the Government many years ago, and now every ATV has one from the factory. You don't have to keep it though, and this is where Motion Pro comes to the rescue. Motion Pro has long had the largest and most complete line of twist throttle conversion kits available for virtually every ATV ever made.
As long as you have some experience working on your ATV, a throttle kit installation is a snap. If you can change a cable, you can install a throttle kit. At this point though, the lawyers are forcing me to say that although this is not a difficult job, if you get it wrong, it could mean very bad things, from damage to your beloved ATV, to injury or even death. You rely on the proper operation of your throttle, whether it is a twist or a thumb, to properly control your ATV. A stuck throttle, or one that inadvertently changes the idle speed of your bike, can be extremely dangerous to you, and everyone around you. So if you have the slightest doubt about your ability to do this job, seek out a professional mechanic, and make sure the job is done right the first time. In addition, it is very important to have a service manual for your ATV, because while this job is pretty basic no matter what ATV you have, there are specific things you will need to know about bodywork removal, carb disassembly, and cable adjustments that can only be found in a factory service manual. So be sure to invest in one before you take on this job, or any other, for that matter.
Okay, now that I have thoroughly intimidated you, it's time to get to work. First step is to disassemble the ATV so that you can get to the stock throttle cable. In most cases this means removing the front bodywork assembly and then the seat and fuel tank so that you can see the carb and the throttle cable assembly. This is where your service manual comes in handy. Make sure to keep track of all those little fasteners that hold everything together!
Once the carb is exposed, it is time to remove the stock cable from the carb. Make sure to note the routing of the cable so that the new twist throttle can be installed the same way.
There are two basic types of carbs on an ATV. The straight pull carb has the cable directly connected to the slide of the carburetor, through the carb cap. The bell crank carb has a pulley on the side of the carb where the cable attaches, typically behind a protective cover.
To remove the cable from a straight pull carb, you have to remove the carb cap and the slide from the carb body, and then remove the cable from the slide itself. It is critical that the carb is clean when you do this, otherwise dirt and debris could fall into the carburetor, causing damage to the engine, and more importantly, it may cause the carb to stick open, with dangerous consequences. So pretend you are a surgeon, and make your work area as clean as possible. This is a great opportunity to clean your whole ATV; I know you have been neglecting cleaning in favor of riding! Once the stock cable has been removed, the new twist throttle cable can be installed in the reverse order you disassembled it. Be careful here, there are a lot of small parts and springs inside the carb and the slide, and they all have to be in the right place. Refer to the shop manual's carb parts drawing, and it will be easier to keep track of everything.
If you have a bell crank type carb, your job is a lot easier. You have to remove the cover on the side of the carb, and the cable will unthread and remove easily. You don't have to worry about getting anything inside the carb, because it is never exposed. One important detail that some owners will have to look for though is some stock throttle cables will have a small slip barrel on a nipple at the end of the inner wire where it mounts to the pulley. You must reuse this slip barrel on the new throttle cable or you will have big problems!
Once the new cable is mounted in the carb, it is time to start work on the throttle. The stock thumb throttle grip must be removed from the handlebar, and then you can remove the complete thumb throttle assembly with the original stock cable still attached, and get ready to mount the new twist throttle. First off, you have to be sure to clean the handlebar thoroughly where the grip was, to remove any left over pieces of the grip and the adhesive. In some circumstances, it is also necessary to remove excess paint from the bar where the throttle tube will be, to make sure the throttle tube can rotate on the bar without hanging up. This is a very important safety step to make sure the throttle will turn freely and not stick or hang up.
Now it is time to mount up the twist throttle. Our kits feature several different throttles, and always make sure to refer to the specific instructions included in the kit for the throttle you have when installing it. The instructions will also direct you on how to install the cable in the new throttle. Always lubricate the throttle cable with a high quality cable lube, and also use a dab of high quality grease on the barrel in the throttle tube, so that everything slides and pivots nicely. Double check at this point that the throttle cable is routed properly, and does not bind or pull too tight when the bars are moved lock to lock.
Once it is all assembled, now is the time to make sure that the cable free play is correct. This is another critical step, as the proper free play is important for proper throttle feel, and also for safety, as a cable that is too tight will cause the rpm's to rise when you turn the handlebars. This could result in unintended acceleration, and loss of control of the ATV. Typical free play is 2-3mm, but this is another time it is important to refer to the service manual for this specification. Additionally, some cables will adjust at the throttle, some at an adjuster inline in the cable, and some down at the carb itself. This is an important step to get right, so take your time and make sure.
Once everything is assembled, it is time to do some static testing before you start the bike, to make sure everything is installed correctly. With the engine off, open and close the throttle. You should hear the carb click closed all the way when you release the throttle, and the throttle should snap back quickly to fully closed. The throttle should have about 3-5 degrees of free play before it starts to pull the cable. When opening the throttle, it should operate smoothly, and without any rough or hard pulling spots. If you feel any of this, go over your work again and make sure everything is okay before going any further.
If everything feels good, now is the time to start the ATV and test it while it is running, but always do the initial tests in NEUTRAL. Do not test the throttle for the first time when it is in gear. If something should go wrong, you don't want to have to deal with a runaway quad. Again, make sure it is in neutral, and then start the bike. It should idle normally. If the idle is high, make sure the cable has the proper free slack. Now turn the bars from left to right, fully lock to lock. The idle should not change at all. If it does, double check the cable routing and make sure it is not being pulled or binding. If not, you may need more cable free play. Once the idle is steady, no matter where the bars are turned, you are ready for the test ride.
A twist throttle feels very different from a thumb throttle, so if this is your first time with a twist, take your time getting used to it. Find a nice roomy area where you can get used to the throttle without having to worry about a lot of obstacles or other traffic. If you spend any time on the internet, you have probably seen some videos of people riding new motorcycles and ATVs, often with disastrous results. You don't want your first ride to end up on You Tube! Be critical about how the ATV behaves, and if something doesn't feel right, don't hesitate to go back over your work. If you have any doubts, consult a professional mechanic, or call on of the friendly techs at Motion Pro. We are always ready to help out if our customers have problems.
If everything's great, go out and ride and enjoy the sweet new twist throttle on your quad, notice how much control you have and how comfortable it is. Your thumb will thank you after just one ride!
Thumbs up to you for a job well done! (Sorry, I couldn't resist).
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