Submitted By Skip: (pococj)


Installing an internal throttle setup is fairly easy, especially if you have access to a TIG welder. While I have installed them with rivets, I really don’t recommend that particular method. The benefit of an internal throttle is the loss of the ugly cables flapping in the breeze, and distracting from the clean looks of your sled. The downside of the deal is that it might be a bit less safe than the typical dual cable the factory installs. But since the single cable was used for more years than not, I seldom worry about it.

There are several internal throttles available. You can still get the original HD version, used through 1972, from various sources, or go with an updated version. V-Twin Mfg, J&P Cycles, Exile, and Direct Parts are several vendors. And while you’re doing the internal throttle you might as well spring for the new bars you’ve been wanting. I located a set of stainless steel Sporty Buckhorns to use. I like the stainless bars because they don’t rust, especially after getting beat by the crap thrown from the log trucks I seem to find myself behind way too many times. Besides, chrome is a ploy to keep you in your garage, shinin’ instead of out riding.

Most of the internal throttles require cutting off about 4 inches of the right bar. The exact amount varies with the particular kit, so read the “destructions”. You can cut the end off with a hacksaw, or use a tubing cutter big enough for the bars. However you make the cut, ensure it is square.

If you have the fat bars that are in vogue, you’ll have to make a sleeve to allow the installation of the internal throttle, as the kits I’ve seen are for one inch bars. After the cut is made, debur with a half-round file or a Dremel-type tool, and finish with some sandpaper. Don’t worry too much about the final finish as it will be covered up by the installation. Just get rid of any burrs, and smooth it to your satisfaction.

Next the internal throttle is disassembled and the stationary portion is inserted into the bar, and a couple spot welds are made through some small holes drilled through the bar, all according to the kit instructions. You can use a stick welder, or a wire welder, but the TIG outfit gives much cleaner results. Make sure the assembly is inserted fully and is parallel with the bar, otherwise the throttle assembly will be cocked. This might result in the handgrip rubbing on the master cylinder and/or switch assembly and giving a not-so-smooth throttle. Another hole will be marked and drilled through the bar for the set screw that fastens the outer sleeve to the throttle housing.

You will have to purchase a universal throttle cable that fits your carburetor. Depending on the bike, you might have to remove your fuel tank. Install the cable on the carb and route it where needed. Come up underneath your risers and feed it on the outside of your bars to the throttle grip area. Mark the outer sleeve where you’ll need to cut it off to length to fit your particular installation. Cut the throttle grip end of the inner cable and remove the inner cable. Now cut the outer sleeve at your mark, using a Dremel or tubing cutter. Take your time with the cut and make sure you dress the inside so your cable won’t get hung up or damaged on a burr. Now cut off the inner cable to the desired length. Prepare the cut end and solder the strands together for about a half inch in length. Slide the inner cable back into the outer sleeve and route it as you did previously.

My bars are two-piece, but if yours are one-piece you’ll need to cut an elongated hole on the underside below your risers. Debur it, of course, and slide your cable assembly through the hole and through your bar. Fasten the inner cable to the moving part of the internal throttle, and fasten the outer sleeve to the stationary part. Lube the moving assembly with some light grease and slip it into the end of the handlebar a