3 Select the appropriate jet(s) from the kit and install them. Use a wrench to prevent the emulsion tube (sometimes called the discharge tube or main jet holder) from turning when the old jet is removed. A loose emulsion tube can create hard-to-diagnose running problems, so make sure it's snug. If for some reason you remove the tube, watch out for a small brass tube or "pill" located above the emulsion tube in some carbs. If the tube is removed, the pill may drop out. Since the pill acts as a guide for the needle, it has a chamfered hole on one side and a straight hole on the other, and it must be positioned correctly with the chamfer toward the top of the carburetor.
4 Reinstall the float bowl and loosen the diaphragm/slide cap screws.
5 Remove the cap and spring, followed by the diaphragm/slide assembly from the carburetor.
6 Remove the OEM needle from the slide. There are several ways to retain that needle, and in some instances the retainer may be screwed down. If that's the case (check the manual), it'll be easier on you if you break the screws or retainer cap loose before removing the slide from the carburetor bore. The needle may also have small spacers or shims either above or below it, so don't just tip the slide upside down and give it a shake.
7 The instructions will provide needle settings. Most kits contain a new needle that's adjusted with an "e"-type clip. Place the e-clip in the correct groove and secure it by placing the rounded portion of the clip on a hard surface and pushing down. You should hear a distinct "click" as it slides home. Be sure to grasp the needle as close to the non-tapered end as possible; it's delicate and if bent will be junk. Make certain any required spacers and shims are installed correctly. Some kits use spacers above the needle clip to hold it in place; some use shims below the clip to provide a fine adjustment.
8 Position the needle in the slide (a dab of grease will prevent any shims from dislodging) and gently drop the slide back into the carburetor. Make absolutely certain that the needle enters the discharge tube (a little jiggle won't hurt) and the diaphragm is properly seated in the groove. A little grease or Vaseline (I know there's a joke here somewhere) should keep it in place.
9 Install the new spring if one was provided, making sure it's seated in the cap. Install the cap and screw it down evenly.
10 All that's left is to reinstall the carbs and road test it; if you really want to make sure it's perfect, head over to the local dyno.
Right Angle - Tech tipUnless you've spent a lifetime crawling around greasy rolling stock, you'd never suspect how many different types of fittings there are. Since I've only reached the geezer stage of my life, I'm sure there are a few I haven't come across, but I'd say there are at least two dozen I'm familiar with. Luckily, the majority of motorcycles use only the type of grease fitting known as a Zerk-the nearly universal bulb-type fittings used on everything from printing presses to bulldozers. They are especially common in automotive and motorcycle applications, so you all probably know what they look like.
Although the business end of a Zerk fitting (where the grease gun plugs in) is a standard size, the fittings are available in a variety of angles. Straight fittings are most common; these work well when you have room to plug in your grease gun and whatever you're working on is positioned on a lift, but not so well when you're down on hands and knees trying to grease your motorcycle in the driveway. At those times a straight fitting may prove awkward to reach, especially if you're using a grease gun with a rigid tube. There are two solutions. The first is to trot down to your local auto-parts store and find a fitting better suited to your needs; make sure you match the threads to the old one. Imported bikes normally use a metric thread, while American bikes use SAE threads. Solution Two is even easier. Although you'll still have to hoof it to the parts store, what you'll look for instead is a right-angle, grease-fitting adapter. The adapter plugs onto the end of your standard grease gun so you can use it at right angles to the fitting. This makes it a lot easier to grease things like suspension linkage while the bike's on its wheels, and as we all know, a greasy suspension is a happy suspension.
Jet Kit Do's And Don'tsDo Your Home Work.Spend a little time researching what the jet kit contains and whether that kit is appropriate for your needs.
Do Set Aside A Clean, Quiet Place To Work.If your shop is under an apple tree, this is one job you might want to farm out.
Do Take The Time To Read The Manual Beforehand.Make sure you understand how to remove and replace the carburetors and to perform necessary adjustments.
Do Be Patient.Carburetor work can be finicky, and it's easy to get off track. If you take your time and complete each step before moving on to the next one, you shouldn't have any problems. Get distracted and you're liable to spend the whole weekend just trying to get the bike to run.
Don't Expect Miracles.A jet kit isn't a magic bullet, and in many cases experimentation may be needed before you hit that golden combination. In some cases you may have to settle for a that's-as-good-as-it'll-get solution.