99 Sportsman 500 carb
 

Good evening. The engine was becoming a little hard to start so I removed the carb for cleaning. Mikuni 34 I believe. I removed the pilot screw from the bowl area during dis-assembly and thought I correctly counted the rotations, but now the engine idles quite high. I then read the manual (a little late) which says don't remove it. I'm looking for the correct number of turns on the pilot screw from the closed position. Thanks.

Welcome! The "pilot jet" along with the main jet tightens down snug.Also make sure the throttle cable has only 1/8" slack at the thumb lever and not tight which can cause idle problems. "If" your talking about the fuel/air adjuster screw under the aluminum block off plug,just turn out 2 turns from a lightly seated position as a base setting. Adjust the knurled idle screw until you have about 1000-1100 rpm idle. Warm the engine up and if you have a carb adjuster or small hands and a small screw driver you can fine tune the adjustment. Turn out a little at a time(counting the turns) until the rpms change,then back in until you hear a change (again counting the turns) and set the mixture screw between both points to where you have a smooth idle and good throttle response.You may have to play around a little with this. OPT

I'm talking about the pilot screw, not a jet, and it is contained within the float bowl chamber and is an adjustable mixture screw, but can't be adjusted once the bowl has been put back on the carb. This is the first Mikuni I've ever run into that has an adjustable screw within the float chamber, and it's got me perplexed as there is no more adjusting it once the carb is assembled.

Never seen a Mikuni carb that's built as you describe for Polaris atvs!! Unless someone has changed out carbs! There is a Fuel/air screw(mainly for the idle circuit) that originally had a round block off plug that is installed from the factory to keep people from tampering with,BUT you can remove the plug and adjust this mixture screw. Plus this mixture screw is in front of the carb bowl and can be adjusted with a small screw driver after the carb is back on the atv. There is no such thing as a "pilot screw" inside the carb that is adjustable,unless you have something that I've never seen before. :huh: Post pics if you can on this carb! Plus look here on the carb under your model. Browse item # 30 is the adjuster,then the spring small washer and o ring.
OPT

Yep, it's #30 on the diagram. Follow the line upward and notice it goes right in to the float chamber. The repair manual calls it a pilot screw, but it's a typical idle circuit screw - pointed on the business end.. It is the original carb. What is not typical is that it is in the float bowl or chamber. Got me :huh: also, I've never seen one like it and I've been into a lot of Mikuni's, mostly on outboards. I appreciate you trying to help me.

You can adjust this small screw with the carb installed,but you have to have a small screw driver or a carb adjuster tool. OR you can just set at TWO turns out and check that you have a good idle and throttle response. Plus make sure the carb slide needle e-clip is set on the second position from the top. The adjuster tool I'm talking about looks like this,if your hands are as big as mine! Motorcycle Tool Air Mixture Carburetor Pilot Screw Adjusting Tool 90 Degree | eBay Or this is the one I have and can do it all,I've even tightened some bowl screws with it,but is costly. http://www.motionpro.com/motorcycle/partno/08-0229/
OPT

OK, I'll take another look. I may have looked at it wrong, maybe the bowl doesn't cover it. Thank you very much for your help. I set it to 2 3/4, that's the problem.

I guarantee the bowl doesn't cover the adjuster screw,just a little tough to get to! OPT

This may help .

http://images.powersportsnetwork.com...6_4911d011.gif