See exploded view of CV Carb for parts identification. We will begin this procedure with carburetors in place and a vacuum comparison gauge ("carb synch") in place.
We will adjust the throttle cable housing to 1/32 of an inch (0.8mm) free play at the adjusting ferrule. (ID #55 Lock (ID #56) right hand ferrule in place. Start engine. Have a friend hold the r.p.m. At 1200 or 1300 r.p.m.. Adjust the left ferrule until the vacuum readings are equal. Tighten lock nut (ID #56). Recheck vacuum-it will undoubtedly be off. Repeat the adjustment and lock down until the result is equal. The engine is probably quite warm-take a half hour coffee break.
Restart the engine and using the idle speed (#34 or #36) adjustment screw, adjust the idle speed to 1000 r.p.m.. Use the vacuum gauge to obtain equal vacuum by adjusting idle speed screws as necessary while retaining the 1000 r.p.m. speed.
Assuming you have this accomplished, we will proceed to the idle mixture screw (#7) Hereafter one screwdriver slot width will be referred to as a "notch". Alternately turn the idle mixture screws one "notch" clockwise until the engine is all but dying because it is too lean. Stop engine and let it cool again. Remove all gauges and plug vacuum ports. Now you will take the screwdriver with you for a test ride.
From a standing start, you will find a bog or lag in the acceleration. Stop, and using your screwdriver, turn the idle mix screw (#7) of both carbs one "notch" counterclockwise. Another short test ride. The bog will probably still be there. If so, turn both carbs one more "notch" counterclockwise. Repeat as needed till the bog disappears. With a cold engine (40-50 degrees) it should bog until engine warms up (2-3 minutes).
At this point the idle mixture is as lean as the machine will tolerate, and yet achieve smooth transition. Anything further counterclockwise would be a waste of fuel. The mixture could be further refined or balanced by using an exhaust gas analyzer. Test both exhaust pipes and raise the mixture of the leaner to match the richer of the two, thus achieving perfect balance.
At this time, reinstall the vacuum gauges and correct any mismatches that have resulted in the meantime. The idle speed will probably have changed. Set that wherever you like it. This should result in a very smooth idle with good response and much more enjoyment than before.
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