So I have a 2002 Kazuma Cougar 250 (4 stroke if that matters). It has an "Exact" branded carb on it, that doesn't have the screw off top (has sort of a dome). It only has 1 external adjustment screw. I'm used to the type with the screw off top/clips to adjust the main needle but this one seems entirely different.

Now for the problem. It has never run exactly right, but close enough (required full choke to start, and feathering the choke for 2-5 minutes), and even once warmed up it would at times bog down. However, now it is much worse. It will not run at all without at least 1/4 choke, then it will idle, and somewhat rev (revs, but has a huge miss about 3000 RPM, if you can get it above that it will rev, but quickly dies back down a few times). It has no power (won't move the 4 wheeler on the slightest incline, will move it on level areas). I have tried setting the mixture screw on the bottom of the carb from 1-4 turns, and it doesn't seem to make much difference, possible slightly better at 1.5, but nothing significant).

The owner's manual is of course useless since it shows the carb, and refers to the screw on the bottom as "throttle idle adjusting screw", and the idle speed adjustment as the mixture screw. I'm hoping for some advice on what to do/check since I'm out of ideas. I guess it could be spark related, but I don't think so since the spark looked good when I pulled the plug.

 

if it bogs down in neutral when you throttle up, your jets are dirty. you shouldn't have to feather the throttle.
your jets will look similiar to this one, the orifices need to be cleaned. if you don't know how, there are a lot of carb cleaning videos on youtube. let us know.

 

use compressed air and carb cleaner. while you're in there, check the float assembly for proper operation..

 

So once cleaned, what if any adjustments are possible on these (and is the external screw for idle mix or main mix)?