VistaCruise Cruise Control for Magnas

Here is some information about the "cruise control" (really just a throttle lock) I installed on my Magna. A number of people expressed some interest when I posted about this on the Magna Guest Board.
 
 
Small overhead view of installation This is an overhead view of the installation. Click on it to see a larger version.
This is a front view. Click on it to see a view with the parts labeled. These labels are used in the installation notes given below.

How does it work?

Study the picture with the labels. (Click on the second picture above to see them.) When you push down on the Thumb Lever, the metal band tightens around the Throttle Clamp Cylinder, and that keeps the throttle from springing back to zero. When you flip the Thumb Clamp back up, you release the metal band and the throttle can move freely.

When it's not engaged, the Throttle Clamp Cylinder is still tightly held onto the throttle by the Rubber Gasket. When you twist the throttle, the Cylinder spins too, slipping inside the metal band.

Even when it's clamped down, you can still twist the grip and change the throttle setting. It's harder than usual, but you can do it. Barring inattention and rider stupidity, the safety impact is minimal.

The reason the metal band doesn't move is that it's connected to the Thumb Lever, which is connected to the Clamp Arm, which is connected to the Bar Clamp, which is connected to the handle bar. (The shin bone's connected to the...) See, you have to mount this whole thing to some rigid spot on the bike, or you can't make it work.

I've also seen a different style of throttle clamp which uses a different rigid spot as the anchor: the metal conduits where the throttle cables leave the start/stop switch assembly. These tend to be smaller and they claim to be easier to install, but it can be hard to can find one with big enough parts for the Magna's one-inch bars, and I'm told they're flimsy and break over time.

How can I get one of these?

To order this item, tell your dealer that the distributor is Tucker/Rocky, and the TR part number is 074043. The name might be "VistaCruise Nylon Universal Cruise Control" or something like that. You also need an adapter for the Magna's one-inch handlebars; that adapter is TR part number 074042. The whole thing shouldn't set you back more than $30 US or so.

How do you install it?

It's pretty easy but there is some fiddling. If the instructions below make it seem hard, it's because I put in each bit of advice I could think of. I didn't know which parts would be obvious and which ones would help people, so I put them all in. Don't forget to review the manufacturer's instructions, too.

In my diagram, the parts are labeled. My labels are probably different from the ones in the manufacturer's instructions; sorry about that but I don't have them any more. Starting from the left, the Bar Clamp (Front and Back) goes around the handlebar between the brake assembly and the start/stop switch assembly. The Clamp Arm reaches across the start/stop switch assembly to the Thumb Lever, which you push on to tighten the metal band around the Throttle Clamp Cylinder. There is a Rubber Gasket inside the Throttle Clamp Cylinder; this is what holds the Cylinder onto the grip. There is a Throttle Clamp Spring which snaps the clamp open when you flip the Thumb Lever back up.

The labeled parts (plus bolts and Allen wrenches) are what you get in the kit. One more part doesn't have a label (sorry!): there is a plastic spacer which extends the Clamp Arm because it isn't long enough to reach across the Magna's (huge!) start/stop switch assembly.

The Bar Clamp that you get with the main Universal unit is too small and you just throw it away. (Or you keep it in among those miscellaneous parts you might find a use for one day.) You use the larger 1" adapter instead, the one you had to buy separately.

I had to loosen my brake assembly and move it down the handlebar a little to make room. Somebody else said he didn't have to. Here is what you can do to get the Bar Clamp and Clamp Arm installed:

  1. Loosen the brake assembly and slide it down the handlebar a couple of inches.
  2. Put on the Bar Clamp and tighten it down almost all the way. When you start, you'll think the part is too small, but it's not: the plastic will bend and shape to the bar.
  3. When the Bar Clamp is almost tight, slide it toward the start/stop switch assembly and get it snug, but don't pinch the two wires that leave the bottom left side of the assembly.
  4. Attach the Clamp Arm to the nipple of the Bar Clamp. Then rotate the Bar Clamp so the Arm goes across the start/stop switch without blocking it or blocking the starter button.
  5. Tighten the Bar Clamp down for keeps.
  6. Slide the brake assembly until it's as close as you can get to the Bar Clamp, rotate it to the right angle, and tighten it down for keeps too. Remember, you don't want this thing coming loose while you're riding!

Your next move is to attach the Thumb Lever to the Throttle Clamp Cylinder while the cylinder is still off the bike. Follow the directions and fiddle with this; it tends to want to spring open on you. When you're done, you'll have a bolt that holds the Thumb Lever onto the Throttle Clamp Cylinder, and the bolt will be sticking out to the left. Eventually it goes into the Clamp Arm.

Getting the Throttle Clamp Cylinder onto the grip is a little bit of a challenge. The gasket arrives as a separate piece, a straight rubber strap. In fact, what you get is two Rubber Gaskets that are molded out of one piece of rubber. You have to cut them apart with a utility knife. You're going to use the smaller one, so put the larger one in the same pile where you put the small Bar Clamp pieces.

Shave the smaller Rubber Gasket until you've taken off what's left of the middle piece that held the two gaskets together. In fact, you might want to whittle a little more off the gasket - as it stands, it is a little too thick for the Magna's grip. However, be sure to keep the lip that runs around one side of the gasket: this keeps it in place and improves the look of the finished installation.

Use a tiny Allen wrench (provided) to loosen the three silver screws that run through the Throttle Clamp Cylinder. Retract them so they don't poke into the inside of the cylinder at all. You're going to put the Rubber Gasket in here. The gasket wraps around the inside of the cylinder with the lip on the outside, to the right. The arrow in my picture is pointing to the exposed right side lip of the gasket; the main body of the gasket is invisible inside the cylinder, filling the space between the cylinder and the hand grip.

What I did to get the cylinder onto the grip was to slip Throttle Clamp Cylinder over the grip and slide it down to where I wanted it without the gasket inside. Then I wedged the Rubber Gasket in between the grip and the cylinder. This is a tight fit (it's supposed to be), but I managed it by moving around the grip, pushing on the opposite side of the cylinder to make the gap bigger and stuffing the gasket in. You might do better to shave off more rubber than I did, put the gasket into the cylinder first, and slide the whole thing down the grip. Don't tighten down the three little screws around the Cylinder yet.

Now attach the Thumb Lever to the Clamp Arm. You use the longer of the two bolts to do this, and you use the plastic spacer they give you, too. The bolt is self-tapping: the first time you screw it in, it's making its own threads in the plastic. Don't screw this in too tight: if you do, the Thumb Lever won't operate properly.

This next part is important: wiggle the Throttle Clamp Cylinder left or right on the grip a tiny bit, until it's exactly parallel to the Bar Clamp on the other side of the start/stop switch. (See my overhead view.)

Why? Because if it's not parallel, then the metal band is wrapping around the Cylinder at an angle, and it won't let the throttle spin freely when it's not engaged. This is bad: you want the throttle to spring back to zero by itself when you are not using the clamp. This is also the point at which you adjust the screw that's on the back of the Throttle Clamp Spring. Too tight, and the clamp holds the throttle all the time. Too loose, and it doesn't hold the throttle even when it's engaged.

Once you have the throttle turning freely (and snapping back!) when the clamp is off, and holding still when the clamp is on, you're almost finished. The last thing is to tighten the three little screws around the outside of the Cylinder until they're flush with the plastic.

Now you're ready to ride! But ride safe: don't use the throttle clamp as a substitute for thinking, watching, anticipating, and reacting.

Back to Allan's Magna page.


August 27, 1998 - apratt@netgate.net