XJ 550 Carb pilot screw function ?

What is the function of the pilot screw on the carb. How doe one determine the correct setting on the four carbs ? The Clymer manual does not give an initial or starting setting for these screws. and warns against making any adjustments. I need to know an initial setting (2 1/2 turns out ?) after a complete carb teardown and rebuild. :roll:

 

2 1/2 to 3 on most XJs I believe. Depends on if you have fine or coarse thread.

Chacal knows which is which. I know my 650 is the 2 1/2 turns.

Let me look through my stuff I believe I have it...

You need either an exhaust gas analyzer ($$, and pain in the butt)
or a color tune plug. The color tune is the easier way and very cool!
It needs to be a cool blue flame.

 

Nobody, not even the dealer, used an EGA for long. You will need a balance rig, either vacuum bottles or a manometer; and a YICS block-off tool. Colortune is nice but not a pure necessity. Best starting point on the carbs is to run the screws in, make note of their initial position and start there.

A lot of the photos you'll find here deal with Hitachi carbs as fitted to the 650s and 750s but the principles are the same.

GET 'EM CLEAN clean clean the first time so you don't have to keep pulling them. Be sure they pass the "clunk test." Bench sync and bench test (with fluid) your float levels before they go back on. Vacuum sync once on the bike, then and only then do you start the fine-tuning with the mixture screws.

AFTER YOU'VE CHECKED AND ADJUSTED THE VALVES.

Do it in any other order and you'll frustrate yourself to no end.

 

I've asked 4 different places around here if they might have a color tune plug, they all said 'oh, no but we have an EGA..."

Guess things move slow around here lol