| Two Barrel Weber on a Honda GL1000 |
| Welcome to an exploration of a recent project where I upgraded the performance and economy of my 1975 Honda GL1000 by the installation of a Weber Progressive Carb in place of the stock intake set. Over the course of three years, I have rebilt my carbs twice and spent many hours tuning and balancing only to continue having trouble with the factory intake system. Those of you familier with this bike are well aware of the difficulties the stock carbs present as they age. In an effort to put these trials behind me, I acquired a two barrel Weber progresive Carb intended for use on the VW flat four engine. It had been installed on a 1600 Dual Port engine and had about 5000 miles on it, and was in great used condition. My thought was it might serve well on my Goldwing if I could figure out how to mount it. Could I buy or would I have to build some kind of adapter for this thing? This began a search for a suitable manifold. I found that there were no "bolt on" options for my project. I did, however get close to that convience. It is my intention, in this article, to try and explain how I made the conversion to the Weber and outline some of the features of the project. I will include a few pictures and drawings and be willing to answer questions via email for those who might want to try the same thing. So, If you're up for it... Here goes! |
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| Pictured is VW Type IV Intake Kit. I used the carb on the right and the base on the left. Also used were the four urethane boots and the air cleaner. |
| Weber Conversion |
| The Weber Progressive model 32/36 with an electric choke proved to be a good choice, as its size is right such that it will fit in place of the stock set without modifying the frame or other structural elements of the bike. What is required tho, is that the stock set be removed and the four aluminum elbows be retained for use in the conversion. They will provide the basis for the install by allowing a ready made connection the the heads and a handy point to attach runners from our new carb intake base section. I haven't, until now discussed the heart of this project. It is found in the use of a VW TYPE IV performance part found at the local VDub shop. SCAT makes a cool carb base that allows the attachment of four runners and their connection to ,the stock Honda intake elbows. It bolts to the bottom of the carb and thru the use of Urethane boots, to the runners which then take advantage of the stock Honda rubber grommets and clamps on the elbows to provide connection the the heads. You will see a picture of the manifold section in the photo above. It provides the carb mount and the four runner stubs for attachment to the rest of the intake system. I first mounted the section to the carb and then using four stiff wires attached to the air cleaner mounting holes, positioned the assembly in the frame above the engine. The wire served as hooks over the top rail of the frame and provided a "mockup" of the carb in its installed position. I oriented the Weber with the fuel inlet to the right of the bike and the primary barrel to the front. This of course allowed for the throttle bellcrank to be placed on the left side. Once the carb was mocked up, I turned my attention to fabricating the intake runners. I found what worked best for me was the use of short sections of stiff wire that were bent to the shape necessary to provide an interconnect between the manifold center section and span the short distance to the intake elbows. |
| This required four "S" curved wires which were then used as templates for the construction on the runners. Each was unique in shape, so I had to keep track of what went where! Ideally, they should all be the same length. That is not possible however. I did try to get close to that ideal. I made my runners from exhaust tubing I purchased at a local speed shop. The diameter proved to be 1 5/8" OD. Because these runners are very short, only about 3 inches long, I simply cut a "birds mouth" with my hot saw and bent the tubing ends together in order to get the "S" curve I needed. Welding and grinding inside and out produced a servicable set of runners that work nicely to both locate the carb and provide an intake path to the engine. No further "mounting" provisions are required. The urethane boots supplied by the VW Shop and the stock rubber gromments coupled to the 1 5/8 tubing provide all the strength that is needed to securely position the intake system. The choke on my carb is electric, so. I connected a wire to the hot side of the coil, ala VW convention, and then to the choke heater. This insured the choke would work when the bike was cold but pull off as the heater was energized with the ignition switch on. My attention then turned to the throttle linkage. This problem proved to be a bit more difficult to solve that the choke hookup. Honda uses a "Push-Pull" throttle arrangement. Two cables operate the stock linkage. I used only the "PULL" cable. I Fabricated a mounting point that took advantage of a carb base plate mounting stud and a short piece of 1/8"x 3/4" flat bar, twisted and drilled to accept the cable adjusting nut and align it with the carb bellcrank. The geometry of these parts is very important in order to get full throttle travel. The carb is positioned in the frame so that the bellcrank is on the left. This requires the left rear stud be used to as the mounting point for the flat bar that is drilled and twisted to align the cable to the bellcrank. An existing hole in the bellcrank accepts the end of the throttle cable and a small oblong bit of 14 gauge sheetmetal is fashioned as a "keeper" for the cable. It gets drilled at each end. One end accepts the throttle cable and the other is attached to the bellcrank shaft via the installed mounting nut. |
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