Grand Prix 250
Main Motorcycle: 1968 Triumph Bonneville
Join Date: Oct 2016
Location: Atlanta Georgia
Other Motorcycle: 2018 Triumph Tiger XRT
New Amal Premiere 930 Installed
After fighting all the issues with having one carb with a pilot bush, the other with a #25 pilot jet that the previous owner left me with, I decided to install new Amal Premiere 930 carbs, with 106 needle jet and 190 Main Jet. I was having trouble with very rich mixtures and poor idle that fouled the plugs quickly with the old miss matched carbs.
Along with the new carbs, I installed new petcocks and fuel lines and fixed all the fuel leaks. I also restored the original air cleaners. I also had to replace the throttle cables because, one of cables was stuck in the carb throttle and had to be cut to remove the old carbs.
One difference between the old 930's and the Premiere is the cable adjusters on the top of the carb. The original 930's did not have an adjuster for the throttle, only a hole for the cable ferrule. So when I ordered new 1968 throttle cables, they were about 1/8 inch too short and did not allow the throttle to seat properly. I had to take about 1/8 inch off the cable housing in various places to get enough exposed cable to allow the throttle to seat.
Because my original issue was a too rich mixture, I tried the needle in the top groove to weaken the mixture. Turns out that this was too lean. Using the air valve to increase the richness of the mixture while running, improved performance. So I moved the needle back to the middle groove, which is the way it came from the factory.
After installation and syncing the carbs They run great! Idle is great. Plug color is on target. Bike starts on first kick. And power and acceleration are much better. They are a little pricey, but it was worth it in my opinion.