Fuel air mixture screw adjustment XJ 900 S

turn the mixture screw all the way in then back it out between 1 1/2 turns to 2 turns
that will get the engine to idle from there set the idle speed with the throttle screw to desired idle rpms
now turn the mixture screw in slowly until you see/hear a fall in rpms
now screw the screw out until again you hear /see a fall in rpms.
half of the number of turns back in from in to out will be the desired air /fuel mixture setting
adjust the idle with the throttle screw if it has altered
you can repeat the procedure again to fine tune the mixture after adjusting the throttle screw

Kescorpio56:
Check your throttle and choke settings. Something is causing the throttle plate in the carburetor to remain open or the governor is improperly set. I would reset the air/fuel mixture screws to one and a quarter turns out and back the idle screw all the way out. Make sure that the throttle cable operates the throttle properly and check the governor setting and reset the governor setting if needed. Start the engine and adjust from there. When the engine starts, adjust the idle screw until the engine idles. Adjust the fuel/air mixture screws for the best idle. Then run the RPM up and adjust the fuel/air mixture screws for the best run/idle combination. Don't forget to adjust the governor if the engine runs too fast or too slowly.

Robert:

As far as the manuals... you might be able to download them at http://www.homelite.com. (you can click on the link) under customer service, you'll find "owner's manuals). To adjust the fuel/air mixture, start the saw and turn the adjustment screws in or out a little at a time until you get the saw running properly. There is no "set" adjustment... as the saw motor ages, those settings will change. If you make adjustments to the fuel/air screws and the saw stops running and starting, turn the adjustment screws all the way in (clockwise) GENTLY... If you force those screws you will damage the needle valve seats! Turn both screws out one and a quarter turns out, and the saw will start. continue adjusting until the saw runs properly. Have patience... it may take a while to get the saw running to your satisfaction.

There are two causes of your problem that I can think of: firstly, it may be that you, even after changing some jets, haven't got the air/fuel mixture right. If i were you, I'd put the standart jets back in, set the needle position to the middle position, and screw the air/fuel mixture screw 2,5 rotations ( 900 degrees) out from fully screwed in. This should return your bike's mixture settings to approximately standart. Then, using this page http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html
determine if you have a rich or a lean mixture, and adjust accordingly. If you have any more questions, or would like me to clarify something, please ask.