I have a 97 King Quad that I was having trouble getting started. When it would start, I would have to feather the throttle to get it to rev. I removed the carburetor and cleaned it out and reinstalled it. Now it starts and idles with just a brief push of the start button, and I stab the throttle and it revs great once, but if I try to rev it multiple times (pushing and releasing the throttle) it stumbles and dies. It will immediately start and idle after it dies, but the revving problem continues. Is this an A/F ratio problem? Where is the A/F screw on this Mikuni carburetor? Thanks.

 

The af screw only adjusts 0-1/4 throttle. If you are rapidly revving it up, any carb machine will load up and run crappy.

 

I wouldn't necessarily call it rapid, just repeated. It's definitely not right, as it was running much better before this problem occurred. So the flexible cable that sets the idle also serves as the AF adjustment? How could I tell if it's loading up or starving for fuel?

 

The flexible cable is probably the idle. The A/F screw is usually on the bottom side of the carb. It is normally an inset flathead screw. I wouldnt adjust it more than a 1/4 to 1/2 turn. Try turning it in first, if it gets worse, go the other way. But my guess is its running rich. But it may not be. Typically turning the screw in will lean it up a little, and out will richen it. Try both ways, and see if there is an improvement.

 

Will do. Thanks for your help.

 

Well, I've made some progress, but it's still not right yet. This would be alot easier if I didn't have to remove the carburetor to adjust the AF screw. What a lousy design.

I currently have the AF screw one full turn out from lightly seated. I've gone as high as two full turns, but it would bog down while revving it in neutral. It wouldn't completely die, but it would struggle and I would have to feather the throttle to keep it revving. With it a one full turn, it revs freely in neutral, but it bogs down under a load (read: my fat a$$ on it). It actually runs very good under load with the choke full on, but it idles too fast this way. With it idling in neutral, choking it increases the RPM's and the exhaust begins to show a hint of black smoke, as I would expect. If it runs better with the choke on, which way do I need to go with the AF screw? Thanks.

 

If your bike is running better with the choke on, i would venture to say you are running lean. Your A/F screw only helps idle, and 1/4 throttle. ADjust your A/F until you get the highest RPMs, then back it off about 1/4 to 1/2 turn and leave it. You may have to rejet. Check to see that you have no air leaks from the airbox, filter, ect. like holes, or if the hose fell off. (if you have a hose) If your getting more air than you should, it will run lean.