That screw is a fuel screw on those machines so turning it clockwise
leans the idle mixture. Generally it should be around 1 turn out from
being fully seated. When you say it loads up and fouls plugs is that at
idle or when you are actually riding it. There is a possibility that
the needle clip position may have to be changed if it is at part
throttle conditions. To do that you need to unscrew the top off the
carb and pull the slide valve. Grab the spring with your fingers and
compress it. Then unhook the throttle cable that is hooked inside of
the slide on a notch. (I cant remember if those carbs had a little
screw in there that you had to undo first before you could get the
throttle cable unattached). Once you have the slide valve in your hand
you will see a jet needle which you can remove and there is a clip that
is in one of five slots. Carefully remove the clip from whatever
position it is in and move it one position closer towards the big end
of the needle. You may want to look at the needle very closely on the
tapered end to see if there is any wear on it. Chances are that it will
have some wear on it if it has never been changed since 79 so you may
want to get two new ones from the dealer. Reverse the procedure to put
everything bac together and you should be okay.
In article <3A55F7D7...@chibardun.net>,