I recently ordered one of your 20mm carbs for my 74 Honda TL125. The TL125 carb is identical to the XR75 carb from the same time period. They share the same Honda part number. That lead me to your web site and all of the dimension information for your 20mm carb convinced me it was worth trying.
When I got the carb I was impressed with the casting quality. It was much better than I expected for an inexpensive carb. I only had to make two slight modifications. At first the throttle cable was too short until I used the original TL125 carb, throttle cable cap for the top of the carb instead of the supplied cable cap. The new cap was taller than the TL original and wouldn't let the throttle close fully. The second issue was I had to drill the 6mm threads out of the carb mounting holes. The TL125 uses 6mm studs from the engine to mount the carb. These were easy to deal with and I had the new carb mounted very quickly.
I didn't have to re-jet the new carb. It seems to work great as it came. The only thing I did was to set the air screw between 3/4 and 1 turn out. I don't have the cough and off idle hesitation that everyone complains about with the TL. I am able to ride the bike at a slow idle and hit the throttle without a problem or cough.
I also used several of your 4mm thick, o-ring carb insulators, p/n 300008 in place of my broken hard plastic stock TL insulator. The stock TL insulator is 15mm thick and used to leak air when the engine was hot. I made a heat shield out of 1/8" thick (~3mm) UHMW plastic that I had in my garage. The total thickness of my heat shield and the o-ring insulators was 15mm just like the stock TL insulator. The air cleaner boot attached to the new carb with no problems at all. Also, the o-rings seal much better than a gasket so I don't have air leaks when the engine is hot.
I have enclosed pictures to show the final installation.
Thanks for your quick service and excellent products.