I need to know wat the carburetor screw needs to be set at, is it 3 and a half?

There is a special tool required as the screw heads are splined, base settings are 1 1/2 turns on both, it should run at this, the L screw will adjust fuel flow from idle to half throttle, the H screw will control the fuel to full rpm.
If the engine struggles to pick up, unscrew L screw a further 1/4 turn, or more until it picks up cleanly.
Now at full revs, gently screw the H screw in until engine sounds sweet, if it starts to die unscrew to achieve full revs.

screw the mixing screws in and back off half a turn. then try again, when started adjust the screws to best suit you need. only half turn each time.

You probably just need a carburetor adjustment. At half-choke the engine is getting an overly rich fuel mixture. This is normal procedure during warm up, but after a couple of minutes, a leaner mixture is needed. That is where adjusting the carburetor comes in. It probably has a Zama or Rueiing carburetor. I use small automotive type wire connectors (plastic) and lightly tap them onto the irregular heads of the adjusting screws. These are marke L and H respectively on the carburetor. The L screw is always closest to the engine. Here is how to make the proper adjustments. If this doesn't work then a good cleaning and/or rebuild of the carb will be needed. They periodically need this done at any rate after a couple years or so. Please view this:
http://www.zamacarb.com/tipspage.html

Hello,
My name is Dane and I am going to assist you in solving your problem.
You will need to adjust the high speed setting on your Carburetor jet. Turning the screw out just 1/2 turn or so should do the trick. It is not so hard to adjust the Carburetor, however you do need a special tool that is very hard to get your hands on, in order to adjust the jet screws. They don't make many engines with plain screw heads anymore. The newer Carburetors are factory set lean so they can pass emission standards. If you have a local dealer, they should adjust the mixture free with a recently purchased unit or for a couple of bucks otherwise. I hope I've helped. Thank you! Dane

most carbs on 2 strokes are bottom the screws out and back it out 1 turn but it may vary for other manufacturers

Half right, one is the idle the other is the air mixture screw, which really only affects idle mixture. The mixture screw is usually about 1.5-2 turns out from screwing it all the way in. then when the bike is idling it is adjusted by screwing it in a little until it bogs down (rich), then screwing it out a little until the engine revs up and down(lean) and finding a smooth engine speed in the middle.
To initially set the idle, look down the carb throat and screw it in until it just starts to lift the slide.
But this doesnt help the starting problem, there may be a blockage in the carb, or if you have cleaned that already, may have to check further, many of those smaller engines need the suction though the standard air cleaner to run properly

The air screw and throttle screw are the only settings on the carb. Bear in mind they only screw in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward. This is the factory setting. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine.


If the screw adjusters were screwed in tight they will likely need to be replaced. The end of the screws will have a depression ring and that little ring can screw up the carb.

Could you take a moment and rate my answer? Thanks!

You need to set the mixtures for the carburetor. You will find a Low and High adjustment screw. At idle turn the screw in or clockwise until the rps starts to decrease. Then start turning it out till you hit max idle rpms. Turn screw back in a quarter to half turn and it should be idling smoothly. Be careful here and get someone to hold saw if necessary but hold in throttle to full speed and do the same with high adjustment screw. turn it in till rpm starts to drop then back it out until you get to max rpm and it won't go any higher then turn it back in a half a turn.

For the carb idle screw and the carb air screw, IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Set the engine idle speed from this point.

Pleas rate this answer. Thanks fergie881!

HELLO THE FIRST THING IS THE CARB CLEAN? A STOPPED UP CARB IS GOING TO GIVE YOU ALL KINDS OF TROUBLES. OLD GAS AND VARNISHING AND RUST ARE CONTAMINATS IS A VERY COMMON PROBLEM.

OK A GENERAL RULE OF THUMB ON THIS IS.FIRST SET THE AIR SCREW OUT ONE AND A HALF TURNS.THEN .TURN THE IDLE UP A LITTLE HIGH.THEN SLOWLY REDUCE IT.AS YOU GET CLOSER TO IT TRYING TO QUIT.THEN START TURNIG YOU AIR SCREW JUST A LITTLE IN ARE OUT.GOING OUT MAY MAKE IT IDLE UP SOME MORE AND THAT IS WHAT YOU WANT TO HAVE HAPPEN. IF SO TURN THE IDLE SCREW OUT A LITTLE MORE NOT MUCH JUST DOWN TO GOOD" PUR". ANOTHER THING I WOULDNT TAKE IT NO MORE THAN A HALF TO THREE QUATERS EAITHER WAY ON THE AIR SCREW.I HAVE SEEN ON SOME BIKES WITH WORN RINGS ARE COMPRESSION PROBLEMS THAT THE AIR SCREW WOULD GO OUT A LITTLE MORE THAN WHAT IS NORMAL.BUT I'AM GOING ON THIS AS YOUR;S IS NOT HAVING THIS PROBLEM.

HOPE THIS HELPS
ELLIOT NEACE