Casting aside every other method I’d heard-of or read about, and clutching my wanky new CarbMate in my hot little hands, I proceeded to suss-out and use a twin-carb tuning method which, for me, works. It is described below.
(1) Set MIXTURE at idle. Take out one spark plug, put it back in its HT cap, and earth it with a length of copper wire to the engine so that it can still spark (I am informed that running the engine with one plug not sparking can fry the Boyer). Start the engine. Adjust its mixture screw out until engine falters, go back the other way (in) until engine falters again, then turn screw back out to a point half-way in between. Go and do the same for the other cylinder.
(2) Set the AMOUNT of air/fuel mixture. Connect up the CarbMate hoses to the balance-tube stubs on the manifolds, and its power leads to the bike’s battery. Start the engine and follow the CarbMate instructions to set the bike’s idle to a speed you are happy with (a nice “rumpety-rumpety” sound) by adjusting the throttle stop screws. Keep fiddling around with these screws until (a) the idle speed seems correct, and (b) the CarbMate is indicating no difference in flow between carbs.
(3) Set TIMING of carb slides opening off idle. Put lollipop sticks (in my case, short lengths of snapped-off hacksaw blade) in the carb throats so that they balance there with one end tucked up against the bottom edge of the slide. Squat down and sight them from the side so that you can see both at once, and crack the throttle open a tad. Both lollipop sticks should start to move at the same instant. If they don’t, then use the individual adjuster on one cable to lengthen/shorten its cable outer until the times of slide lift-off are identical. Finally, check the overall throttle-cable slack up at the twistgrip end of the cable and, if necessary, adjust it to maker's specs using the top cable-outer adjuster located under the handlebar.
Then go out and enjoy your powerful, smooth-running Bonneville, you lucky devil!
Actually, there are still a lot of things that can get you all confused here.
Like pilot jets that have gotten gummed up with stale fuel, or an ignition switch in its dotage that keeps cutting in and out in response to engine vibration.
So many traps for young players!
But more on that later.
