hey guys if anyone could help me please...i am looking for a step by step diagram
on how to adjust my 2 stroke carb...any help would be apreachiated...i have a polaris 400L 4x4 400cc 2 stroke....

 

also if i try to start it it wont start...if i put my hand over the air filter it starts right up....if its rev..it stays on....once i let go of the gas it last about a few seconds and dies...its very frustrating...so i figure its the carb that needs adjustments

 

it sounds as if your choke circuit is not working. first thing to do is remove the plunger from the carb. its the one off to the side of the carb. not the one right in the middle. remove it and while its out move the lever on the dash to see if its moving. if it is then look down in the hole that it came out of and see if its dirty. try to clean it out. second thing is it sounds like the pilot jet is clogged too if it will run while reved. that requires you to take the carb loose and remove the float bowl. take a small wire and push it through the little brass screw looking thing off to the side of the carb.

here is a really good generic walkthrough that will get you started
http://www.ripperd.com/ftp/adm..._rebuild/

 

If your carb is dirty, and gummed up, then I recommend to pull it off and clean it properly. A little extra work goes a long way. Jets are ceap. I'venever had good success trying to clean them. Pushing a piece of wire through a jet or carb is never a good idea, although it can be done. Just very carefully as you don't want to change the diameter of the orifice.

Take it off, disassemble, soak all parts in good quality commercial carb cleaner at least 24 hours. Make sure that any rubber parts are removd first. Then re-assemble with new pilot and main jets. If the needle and seat are good you can reuse them. If in doubt, change them. Get a manual and follow the procedure for your carb. Pretty straight forward. Adjust float, air screw, and choke cable as per specs. It never hurts to replace the choke plunger as well. The rubber end on the plunger tends to harden and conform to the choke tube and not seal properly.

When you are ready for re-assembly and if you have questions, just ask. There are many on here that can help. Mikuni carbs for 2 strokes are pretty straight forward. Here is a all-park idea with them. Check you manual for proper settings.

mikuni carbs

air screw 1-1/2 to 1-1/4 out if you need to turn more or less for idle change pilot jet one size

choke adjustment
factory had nice but useless plastic measurement guides. best method is to make sure choke plunger is clean and smooth as well as bore. back off adjuster to make sure plunger is in bottom. next turn adjuster till you have 1/8-1/16 slack in cable before choke leaves seat.. test on cable or lever.

throttle valve
common problem on this is marked up screws and that people forget to put back in the plastic washer that goes between needle clip and throttle valve.

needle clip position should be middle. one up or down usually means wrong main jet

throttle valve slack is adjusted first. with carb off adjust cable so that valve just clears the opening on engine side.

duals both valves should open at same time.. i use finger feel or guage.

common problem on mikunis that have sat for any lenght of time over 3 months is plugged pilot jets. mains are usually obvious if plugged.

inlet needle and seats do wear out change if you have common flooding problem otherwise just clean and reinstall.

float height is parrallel to carb body.

thottle valve adjustment cold.. back out screw reach in carb and feel throttle valve turn in screw until it just touches valve then turn in additional 3 turns.

Hope this helps

Jeff