Wont start w/o turning idle screw all the way in//just had the valves redone and the carb rebuilt///after it dies start you cnat turn the idle screw back out to a level idle and its fine. Have had the bike to several local machanics and they have given up on the bike.

get a colortune tool.it shows how your firing.read instructions that come with,so simple to tune carb in with.sounds like pilot out of adjustment.could also have a leak in ur carb boot or head.take a torch without lighting open valve with motor running run torch around gaskets and front of carb boot listen for change in motor.if it gets higher rev uve found a leak.

Hey William,
By rebuilt, do you mean the carburetor?? ..or the engine??.. if you rebuilt the carb and you did not remove these screws ( and count the revolutions out from lightly seated), then you did not do the rebuild the carb correctly.. sorry.. What, exactly did you do to the carburetor?? Please reply on here to me..with details!!
thanks..

I cannot understand why someone that claims to have "rebuilt" a carburetor actually missed the BASCIS of carb rebuilding 090.. the air screw (the one on the angle toward the back of the carb has/is connected to the pilot jet system and the idle system, the passages that use this system must be perfectly clean for the engine to run properly.... the air screw has a spring. a spring seat and a o-ring for sealing on it.. the screw setting starts at 1 & 1/2 turns out from lightly seated.. then set the screw in the very side of the carburetor (its the one that controls the idle speed).. once you get the machine warmed up and cleaned out.. let it idle, turn the air screw in and out SLOWLY about a 1/4 turn at a time..EACH TIME ..waiting until the idle settles and then until you reach the point the machine idles as high as possible, then turn in it 1/8 of a turn.. then set the idle speed with the "side screw" to a speed you like... good luck...thanks!!

Re-adjust the jet screw on carb turn all the way in then turn 11/4 turn then go from there in or out. Reset idle screw. Make sure all vacuum lines are all in right place.

reset the idle mixture screws at the base of the carbs.
all the way in then back out 2 turns

Try adjusting you mixture a little richer, 1/8 turn on the fuel screw. If this doesn't help get to idle, you will need to rebuild the carb. make sure you get a complete kit to include the float and throttle springs as well as jets and gaskets. Write down your initial mixture settings and try them again on your rebuilt carb. Should be fine. Bending float arms for travel length is tricky, be careful as they can easily break off making them useless. The rest of the process is pretty straightforward. Ensure you place the needle jet keeper ring on the correct groove and the throttle moves smoothly against the spring tension on the cable above the needle valve.

If you rebuilt the carb did you turn any of the screws on the carb while cleaning or take out, you might have just the low idle screw closed a little to much open half turn and see what happens. If you look at the carb where needle screws are located on the side,if you have two screws it will be stamped with an " L " and?or an " H " next to each screw. If you only have one screw then turn that one, to left to get more fuel. Good Luck...

You have two setting screws on front of carb, You start off by adjusting all the way to the left, Then back off 3/4 turn to both setting screws, Then you have to set your air fuel mixture by just slowly turn your setting clock wise do so until vibration go away. Sorry there is no easy way to explain, Good luck to you,

The carbs are probably out of sync. Set the carbs so that both slides crack open at exactly the same moment. Next, balance the carbs by disconnecting one spark plug then turning the throttle screw on the runing carb to a slower and slower rpm until the bike stops idling on one cylinder. Now reconnect that plug and disconnect the other. Do the same thing to the point the engine dies trying to run on one cylinder. Now start the bike up with both sparkplugs in place. The idle speed will be high, but now the carbs are in balance. Turn each throttle screw down in equal portions until proper idle speed is attained. It would be a good idea to set the valve lash also. If the backfire continues, chances are the valves need to be re-seated. Re-sync and balance the carbs after the valve re-seating. Please rate my answer. Thanks.

There are two adjustments. 1) Idle speed ( the screw that contacts the throttle plate. 2) The high speed. Location depends on carb, if it's a venturi-jet (not attached to tank, it's on the bottom, start at 3/4 turn out from seat, adjust in or out until motor goes from idle to full throttle without stumble. There are only two screws so they shouldn't be hard to find, idle is where your throttle cable hooks.

Did you try to increase the idling adjustment screw?
Check the spark plugs for its condition and thn reset the air-mixture screw.
Standard procedure for setting air-mixture screw...tight it all the way in, taking care to not over tighten or the tip of the screw may be damaged, thn turn outwards 2 & half to 3 turns, start your bike's engine ,run it to normal temp. and the reset the screw + - alittle either way and you should notice the difference in the idling and all.
Its better too, to also check the valve clearance !
Hope this helps!