Im trying to adjust the fuel screw on bottom of carb . did polaris make a tool for it? can't get my hand in there. Is there a tool and a procedure you guys used?

 

Set it at 2 turns out initially. Crank it up and allow it to get to operating temperature.Adjust the idle screw for a good even idle then slowly turn the pilot screw out until you reach its highest rpm(shouldn't take more than one full turn) then turn back in 1/4 turn. This should be close enough to where you can hit the throttle with no hesitation or bog. That is if everything else is right such as the main jet,needle clip position,etc.. Fairly easy with the right tool.Motion Pro Motorcycle Carburetor Pilot Screw Adjusting Tool Carb Mixture 08 0119 | eBay

 

You have used that exact one as the one in the ebay link? the bit in that one does not come out and seems a little short...what do you think?

 

also the bog is when its cold...wouldnt i adjust it when cold?

 

Plenty of people have used this cheaper one,but no,I have this one.. As you say more versatile but costs 3 times as much as the one I linked to. Motion Pro 90 Degree Carb Tool With Bits | MotoSport Plus I have short and extended bits for just about all type carb situations. And no,you don't adjust the carb when cold! Keep it running long enough to get it warm and then is when you fine tune the pilot screw. Again this pilot screw or idle fuel screw as it's sometimes called is mainly for a good smooth idle through the pilot jet. Like I mentioned the main jet,slide needle clip position,air box and filter has the main control from a little off idle,1/4 throttle or so upwards and has to be right or it will bog or hesistate. Look over this fuel section again to see how it works.You have the BST34 carb.https://www.google.com/url?sa=t&rct=...U2gGlaHJWSIlbA

 

this is the third carb i have installed...plus the one it came with. pilot jet on this carb is 40 and main jet is a 155. I live in central new york....could this be the bog I'm getting when cold?

or can this be a timing issue ? everywhere we looked someone was messing around on this bike. The rings,piston (bored 25mm over)and valve seats were all worn...now new. But I'm thinking possibly someone may of kicked timing around to get by worn top end of engine to get it to run better.
Could the timing chain be off one tooth when i installed head do this. Spoke to my mechanic buddy and he says if i were off a tooth it never would run...what do you think? sorry to bombard you with all this info

 

Shouldn't take three carbs and working on something without some kind of guide. If you'd down load this manual it can help in so many ways from jetting changes(if needed) to trouble shooting guides for electrical,mechanical problems plus it does show how to check timing,etc. Don't guess at something and blindly throw parts at a machine.2000 POLARIS SPORTSMAN 335 4X4 ATV REPAIR MANUAL

 

Can you use a regular automotive timing light?

 

You'd also need an accurate rpm meter to check timing with an automotive timing light. It can be used to see if an ignition is possibly breaking down. Many old techs have done this. If the light stays constant at high rpms,then ignition wouldn't likely be the problem. If the light pulses in time with any engine miss,then that's a sign that possibly you have a break down. The manual shows you the basics on how timing is set and whether it's off or not mechanical wise. You'll have detailed pics and instructions like this one the Sportsman 500. Just get the manual for your machine and you'll be surprised what all it can help you with.

 

I have the exact same issue and its killin me. Brand new carb, fuel pump, lines, and it only runs well if partially plugging intake with hand. Cold compression 62psi.

Seems like low vacuum, however no leak could be found, I am wondering if valve issue? New to 4 strokes