I bought it 10 years ago when they were the rage. Built the intake a year ago and fitted it this past spring. I mostly learned how NOT to do it. But it ran right off and ran very well. There's a pronounced increase in power you can feel over the downdraft. Had a fuel leak and this is probably why I got it so cheap but once found JB weld did the rest. I was told to go 180 so I drilled the jets and it ran fantastic but the wide band says too rich so I bought 20 jets off Amazon that were under 110 and tried 120 by drilling out 4 (WAY too lean) So I think they are 130 or 135 now and the stock R-1 are 146. I'll bet I should have never touched them, but ah well I learned a lot about this. I connected the L series intake coolant line through the carbs and out to the by-pass but warm or cold didn't seem to make much difference. Had to convert from linkage to throttle cable. The rotating thing on the carburetor that the cable pulls to open the throttle is smaller than an Hitachi that has the same thing so the pedal doesn't have to move as far between idle and full throttle. I had to modify the gas pedal fulcrum point to increase the travel or the pedal seems more like an on/off switch. In my travels (Canby) I found a Hitachi SU choke cable and knob, probably from an SSS but possibly a Roadster. I got that working where before I used a Windex squirt of gas in each to get it started. The R-1s have an adjustable fast idle speed cable that you twist but it's too short. I'm going to make something that fits under the dash.
It starts cold and idles at 400 RPMs!!! It's incredible, but you can't drive it like this and why an easy to use fast idle adjustment in the car would be handy. Once it warms up the idle slowly goes up so you have to keep turning it down. Anyway once warmed, there is ZERO hesitation or bog if you floor it at idle or anywhere. The constant velocity carb is like that, there is no transition from idle to primary or primary to secondary. There is no need for an accelerator pump because it always has the right amount of air going through it to pull in the correct amount of fuel. Smooth as silk and it moans, and at 3k it starts to roar louder and louder. (more addicting than crack, that sound) With the down draft it was wrung out at 5K and a long long wait to get to 6k. I tried it once and not again. Now it climbs through 5-6 kas fast as 3 to 4k so you really have to watch it in first and second or it gets away on you.
Still haven't figured out a vacuum advance for it. Nor have I figured out what to do about the cank case vent / PCV.