I recently got tired of fiddling with my Strombergs and wanted to try the progressive Weber downdraft carburetor setup on my TR6. It was sold as a kit with spoon-shaped manifold extensions to make the downdraft carb fit on a side-draft engine. I was skeptical of the idea but the price was very attractive. A few notes:
1. They fit, but not well. The carburetors sit backwards in my opinion, with the primaries being furthest away from the intake. Air flow needs to go all the way past the secondaries in order to get to the engine. They should be turned the other way around, because the primaries get used most and the secondaries only open when you floor it. Also, it is difficult to get to all the necessary fastening points, and I had to dent the inside of the wheel well in order to make clearance for a vacuum port sticking out on one carb.
2. They run the motor really nice. I had to change the stock main jets from 140 to 150 to get the mixture right- probably because I shaved 1/8" off the head a couple years ago. It was acting lean at first. But now it is running smoother than ever before and has more power. Gas mileage went down a few points, however.
3. You need to hook up the hot water port. I didn't do it because I thought it was an option for cold-weather climates and I live on a tropical island. Wrong. When I run at-speed, the carbs get so cold they condensate and sometimes this leaves water in those cute little spoon manifold extensions after I shut down. It makes for fun starting, the next time.
All-in, if I had to do it again, I would probably look for a side-draft setup. I love Webers and am not sorry with where I ended-up, but it took some gymnastics to get here.
Mahalo, MH
1. They fit, but not well. The carburetors sit backwards in my opinion, with the primaries being furthest away from the intake. Air flow needs to go all the way past the secondaries in order to get to the engine. They should be turned the other way around, because the primaries get used most and the secondaries only open when you floor it. Also, it is difficult to get to all the necessary fastening points, and I had to dent the inside of the wheel well in order to make clearance for a vacuum port sticking out on one carb.
2. They run the motor really nice. I had to change the stock main jets from 140 to 150 to get the mixture right- probably because I shaved 1/8" off the head a couple years ago. It was acting lean at first. But now it is running smoother than ever before and has more power. Gas mileage went down a few points, however.
3. You need to hook up the hot water port. I didn't do it because I thought it was an option for cold-weather climates and I live on a tropical island. Wrong. When I run at-speed, the carbs get so cold they condensate and sometimes this leaves water in those cute little spoon manifold extensions after I shut down. It makes for fun starting, the next time.
All-in, if I had to do it again, I would probably look for a side-draft setup. I love Webers and am not sorry with where I ended-up, but it took some gymnastics to get here.
Mahalo, MH