"If you want a good, reliable, classic feeling motorcycle, it's tough to beat a Sportster."
--Colorado Jeff
From the Boutique:
1975 XLCH Conversion to Keihin CV From Zenith Bendix
by Steven Parfitt
Material
CV Carb 27480-97 $75.00 Purchased used on XL-List Flange Adapter 03-264 $9.99 Texas Iron VOES 26566-91 $42.00 Smith Brothers HD K&N Filter 84555 $23.00 Fog Hollow 7" Round A/C 12-122 $24.95 Fog Hollow - (Early Round air cleaner replica with HD Like emblem)Editor's Note: CV's can go for anywhere from 15 to 100 bucks, so it pays to shop around. Also, you will only need to purchase a VOES if your ignition is capable of using it. The point? This conversion can be done for less than $100, I did.
Procedure
Remove gas tank , Air Cleaner, choke cable, throttle cable and carburetor.Install the Flange adapter.
NOTE: I recommend that you throw away the band clamp and replace it with a 1 5/16" - 2 1/4" unit from your local parts store. The clamp that came with my flange was a skinny P.O.S..
Install the carburetor in the flange mount adapter, snug down the band clamp for temporary support, and try to put your gas tank back on. Look for interference with the CV. Remove the tank after you check for fit, and proceed with the mounting bracket.
I found that when installing the gas tank, I had to cut off the Push-Cable barrel mount. It hit the fuel shut-off on my tank.
I did not receive an air filter with my carb, and wished to use the round filter that came with my Bendix/Zenith. I also wanted to change to a K&N Filter. To achieve this, I had to make a new backing plate for the carb, which would fit the K&N Filter. I cut it from 1/8" aluminum plate. I drilled it to mount to the CV and drilled out the center hole and filed it to the correct size.
Once I had the backing plate, I needed to figure how to support the carburetor. I did not trust using the band clamp/flange mount alone. I fashioned an "L" shaped support bracket from 3/8" X 3/4" 6061 aluminum. I drilled it to fit the bolt for the top engine mount. The support extends behind the CV about four inches from the mount point. It is bent around the CV with a multi point curve. (6061 is good for machining, but does not bend well, so all bends are large radius) I bent the support down with about a 1" radius bend to be flush in rear of the backing plate for the CV. This 90 degree bend is actually four 22.5degree bends instead of one 90 degree bend. The bracket has one hole drilled and tapped for 1/4-20, and a second hole drilled but not tapped. The lower tapped hole has a 1/4-20 bolt installed with locktite red. The upper hole is one of two holes for the air cleaner/cover mount.
A second "Front Plate" was cut from aluminum plate to fit the indention in the front of the K&N filter. This plate has two holes at 9:00 and 3:00 for bolts to attach it to the back plate. The two plates sandwich the K&N filter, and become the air filter itself. I drilled two holes in the front plate at 12:00 and 6:00 for the original air cleaner cover to mount to the new filter assembly, as a false front for looks. I used self locking nuts to retain all hardware.
Modifying existing throttle cable.
The standard throttle cable for the 1975 XLCH with Bendix Zenith carburetor has a ferule on the throttle control end, and is a straight tinned cable on the carburetor end. This end normally fits through a small hole with a set-screw to retain it.The CV requires a ferrule on each end of the cable. I would have needed to replace the throttle control on the handlebar as well as the cable to upgrade mine since the ferrule will not fit through the 90 degree tubing on the handle.
I made a barrel out of a 3/8" long piece of 1/4"dia rod (unthreaded portion of a 1/4-20 bolt). Drill a hole through its axis and tapped it with a 6-32 tap. Then drill across its axis with a drill that is slightly larger in diameter than the throttle cable. Cut off two 6-32 screws so that there is just enough thread to screw in to the point where it blocks the hole in the ferrule. Be sure to file the end smooth and eliminate any sharp edges. Locktite one screw in place with the face of the screw at the hole. This becomes the ferrule for the new end of the cable. Trim back about 1-1/4" of sheath and cut off 1" of the spiral steel body of the cable sheath. Route the throttle cable to the CV carburetor, put the new Ferrule in the bell-crank, and insert the cable in the hole in it. Screw the second screw in to compress the cable in place. Locktite the second screw when you have the cable length adjusted properly.
Choke Replacement Cable:
The new equivalent is called an Enricher Cable. This is routed around the rear of the carburetor instead of the front as in the Z/B. I bought a replacement Enricher cable, but it was too short to fit the normal mount with the ignition switch. I made a bracket that mounts with the rear gas tank bolt. I plan on getting a longer cable in the future, and re-routing it to the ignition switch plate.
VOES:
If you are using solid state ignition such as the HI-4, you will need the VOES switch. If you have points, or one of the electronic ignition modules that doesn't use the VOES, then you can leave it off but need to plug the top vacuum line to prevent a vacuum leak. I made a angle bracket to hold the VOES. I bent the flange to wrap around the top tube of the frame. I clamped it in a vice with a 1" round piece of galvanized pipe and used a 2lb hammer to form it around the pipe. Cable Tie Wraps are used to affix it to the frame. One wire from the VOES goes to the HI-4 and the second wire goes to ground.
Overflow hose:
This confused me at first, as I thought it was a second vacuum hose. The hose at the bottom of the CV is an overflow hose. I routed it between the front cylinder and the push-rod tubes, then down between the engine case and the generator.My overall impression of the CV is that it is a great improvement over the Zenith/Bendix carburetor. The Flange adapter causes it to stick out a little farther than stock. My shin hits the air cleaner, and if I were to do it over, I probably would offset the air cleaner to the front of the engine, and rout the support bracket to the front instead of the rear of the backing plate. This would give a little more leg clearance. I do not know how this will effect forward controls.
I still need to re-jet the carb, and adjust my ignition timing. Top speed so far has been around 96mph, with some omph left.
