My 1983 wont start but it back fires through the exhaust andits a two stroke liquid colled and some one told me the valve is in wrong what could be the problem

That's because it's on the down stroke. When the piston comes up it'll open the exhaust valve, when the piston hits top dead centre the exhaust valve will close and the inlet valve will open to fire it back into the down stroke.

It depends on which TDC you are talking about, compression TDC or exhaust TDC. On the compression stroke, no valves will open after TDC-this is when combustion has occured, the power stroke. When the piston reaches bottom and starts up on the exhaust stroke, then exhaust valve will open. At TDC of exhaust stroke, exhaust valve will be closed, and the intake valve will then open as piston is moving down.
If you have the intake valve opening right after TDC, you are on the exhaust stroke of that cylinder. The exhaust valve is only open during upward movement of the piston on the exhaust stroke. Immediately after TDC of exhaust stroke, the intake will open as the piston travels downward.

The firing order for a 1998 Ford Expedition is 1-3-2-7-6-5-4-8 for the 4.6 liter, 2wd model.-----------------------------------------------------------------------------------
Original Launch X431 Master

You're wrong. It should not fire when the exhaust valve is open-that is the exhaust stroke. As the piston moves down after the exhaust stroke, the intake valve opens and the air-fuel mixture is pulled into the cylinder. Then piston travels up, compressing the mixture( both valves are closed, now), and at the top of this stroke the ignition fires, driving the piston down.
Sounds like your timing is a bit too soon, if it's firing when the intake is open. Try retarding the time just a bit.
If that doesn't work, find tdc of the compression stroke of number one cylinder: pull the sparkplug out and turn the crank around by hand (with a socket on the crank pulley) with your finger over the plug hole. As the crank comes around to the zero mark (TDC), you will feel pressure bui;ld up on your finger if you are on the compression stroke. If you are on the exhaust stroke there will not be pressure buildup as the piston approaches TDC. Once you have number one cylinder at TDC of the compression stroke, the rotor will be pointing to the number one plug wire tower on the distributor cap. If the dist. is off 180, rotor will be pointing opposite of number one.

If you have a weak spark it will not start since under compression it takes a much stronger spark to jump the gap as compared to a spark in normal air pressure. Try a good known working coil.

Set the piston to TDC (top dead center) this is the higest point the piston will rise before moving on to the down stroke, either by lining up the marks on the crank rotor or a long screw driver (large handle so it wont fall in) down the plug hole and watch for the highest point lock or hold at this point. The cams should be fitted next on the 'compression' stroke meaing the all valves should be closed when the cams are seated (no valves being pressed by cams) generally at this point the cam lobs face away from the valves, next stroke down (ignition of fuel) valves should be closed with the exhaust cam moving round ready to rock on to the exhaust valve as the piston rises to the top again (4th stroke exhaust) as the exhaust valve lobe rocks off the intake cam lobe should be starting to rock on opening the intake valve on the down stroke of the pistion.
Trun the engine over by hand to make sure no valves are knocking the piston.
Should be as follows
1. all valve clearance free/rocking at ' TDC 1st 'down' stroke (ignition of fuel) valves closed exhaust moving round but not pressing valve ,
2. 2nd stroke 'up' exhaust valve rocking open and closing as piston tops with the intake ready to rock on as the exhaust closes and piston tops (exhaust),
3.3rd stroke 'down' (intake of fuel) as the piston moves down the intake valve should be opening.
4. 4th stroke 'up' compression of fuel all valves rocking closed as the piston rises for the compression stroke back to TDC all valves closed/rocking free.

Intake, compression , ignition and exhaust. (**** squeeze bang blow)

Their are 2 different top dead centers/TDC ,one is TDC of Exhaust stroke and the other is TDC compression stroke . You must have the TDC compression stroke . At this point -both valvesare closed.  If it is TDC Exhaust stroke You will be @ a point where the Exhaust valve is just closed and the Intake valve is just opening.After you have established the proper relation of the crankshaft and Camshaft ,you must do ignition timing.   

With engine Crankshaft on TDC and cam timing set correctly this is the position where No. 1 cylinder is firing at the start of the power stroke. At this point No. 4 cylinder is also at TDC but is just at the end of the exhaust stroke and starting the intake stroke so the exhaust valve will be almost finished closing and the inlet valve will just be starting to open. This is referred to as the inlet and exhaust valves rocking.

Your crankshaft turns 2x times the camshaft. Put it this way as # 1 cylinder reaches TDC (top dead center) of the firing/compression stroke, and this will be after a (8 degs BTDC) spark to ignite the air/fuel mix, the # 3 cyl. will be at BDC of the intake stroke and as #1 begins its power down stroke, (during explosion of air/fuel mix), #3 begins its compression up stroke, the #4 cyl. will be coming down with #1 cyl. but #4 will be in the beginning of its intake down stroke, and #2 cyl. will be coming up with #3 but #2will be in its BDC of the exhaust stroke. Which has just fired previously to #1. 1342134213421342 etc. Now the cam turns to open / close the valves; In the outline above, #1 cyl. valves will both be closed. #3 cyl. will have the intake starting to close at this point. #4 cyl. will just be starting to open its intake valve, and #2 will be starting to open its exhaust valve. Is all this clear as mud? So as the crank makes one full rotation (in a 4cyl. engine) only the firing of one cylinder has happened.and at every rotation one cyl. will fire. So #1 at TDC then one full rotation, #1 back at TDC, but this TDC is half of its 4 cycles, (1)Intake, (2)compression, (3)power, (4)exhaust. this 1234 refers to the 4 cycles of the rotation not firing order.

Is this a quiz? Each cylinder contains one piston that takes four strokes to coplete a a full cycle. the intake-down,compression-up, power-down, exhaust -up.
A two stroke has up and down only . Compression and power Now, I thik you really meant the firing order. I'm not sure but Would make sense 2-3-2?