The engine will not turn over. The battery has a charge, and the alternator is in good shape. Could not smell gas on the spark plugs, and they were bone dry. The engine is trying to turn over, but won't actually finish

Ok, I may cover stuff here you've already done. My assumption is that this is a push button starter. Does it have a Kick Starter?
What EXACTLY is it doing when you try to start it? This can give clues as to where the problem could be. Have you been having any other issues with the bike like lack of power, Bad gas mileage? Again that can give clues.
-Lazy turn over could be a battery issue. Bad batteries can hold full charge but don't have the actual force to turn the starter motor over, (Amp flow)>.
-Just spinning suggests No spark. 'Coughing' and trying suggests fuel supply issues.
Try checking the simple 'Silly' stuff like does the bike have a fuel valve on the tank, (a Petcock valve)? You may have turned it to the 'Off' position and forgotten to turn it back to the 'Open' position. Yes, I've done that!
-When was it last serviced? Dirty filters can cause bigger issues than you would expect.
I'm assuming your wife's bike still runs so it's unlikely to be wrong fuel.
When you say the spark plugs are "Dry" is this referring to the actual spark terminals inside the engine or just the outside of the engine. If you've cranked the engine the spark plugs should be wet and smell of fuel. Did you check All the spark plugs were generating a good, strong blue spark?
A lot of modern bikes now have electronics so it could also be something there. For this I would suggest you get a good bike mechanics opinion as they can physically look at the bike to see what it is or isn't doing.
Comment below and I'll see if I can help you more.

Probably gas or spark related. Check for spark on a spark plug wire, or on a couple of plug wires would be better. If you have a strong blue spark, then the coils are good, ignition is good, and you will need to see if gas is getting up to the engine. Do you hear the fuel pump come on?

Does it crank well and all that but with no spark or is the battery just dead? If the battery is dead, it either won't charge while alternator is spinning or the alternator doesn't charge well enough to keep the battery charged well. If it jumps and runs indefinitely, battery is done. If it jumps and dies, alternator is done. If battery and alternator are fine, and you have no spark, you may need a new coil, new spark plug wires if they are worn out and too resistant, pick up coil inside of distributor, or you may have some other ignition system issue.

Most times when an alternator fails, it starts charging less and less till the car won't keep running or it won't start the next time. If the alternator hasn't failed, the battery needs replacing. If your battery is 5 or more years old this is a very good possibility. If your alternator failed and you have killed your battery many times before replace them both. Each time you drain a battery to dead you lose about 10% of its current capacity.

If the battery is fine and engine will not turn, starter may need replacing. Hope I helped.

You need to check for spark. You probably do not have spark causing the engine to flood. Check your ignition parts and see what shape they are in. If you have not had a tune up in 50,000 miles you may want to start there.

If the engine calls for a 5w 30 weight motor oil,then stick with it,and use a blend,or full synthetic oil,castrol is the best,and use this fuel treatment,if you want to see a difference in fuel usage ,LUCAS fuel treatment,use it with as less as possible,fuel.It will work better,to clean the fuel system,and the injectors.Make sure the battery is real good,and check the alternator at the battery with engine running,it should read,13.65 volts,to 14.25 volts,with everything on,anything less,is not enough,replace the alternator.If the charging system,battery included,is not up to par,then the alternator works hard all the time trying to charge the battery up to full ,and it never does,because of ,either the battery is not in good shape,or the alternator is charging too little,and when the alternator engages,it pulls down on the engine,therefore using fuel more.

Take all the spark plugs out, then try cranking it to see if you excess gas in the cylinders. You may want disconnect the coil pack so you you don't have a fire, in case you get gas spraying out of the spark plug holes. If you get gas out of the plug holes,then look at fuel pressure regulator. If you pull the vacuum line off and there is gas there the regulator is shot.

if your oil smells like gas you need an oil change badly. while running the alternator should be charging at 13 up to 14 volts if it's not doing that then the alternator is bad if that battery is charged and it's hard to turn over then there is a loose connection either at the battery or the starter if everything is tight lean toward the starter

back to basics.. it turns over? starting system is ok... does it have fuel? does it have spark? is it getting air?....many many vacuum lines in that year model ..any many could be compromised...waft carb cleaner through intake to see if it lights up... check for spark if not .... then continue with compression test for engine internal health and timing issues... too many things to list here.... good luck adn avdive

Well if you start your car and its dieing at a stop sign. That usually means you have a bad alternator. Your alternator is wat charges the battery when the car is on, and the more you eccelerate the car, the faster the belt spends on the alternator and the more juice is pumped to the battery. So I would have your alternator checked out. Im pretty sure thats why your stopping at stop signs. As far as the smoke and the smells gassy. You have t remember its an older carborated truck, so its going to smoke out of the exaust and its going to run a little rich, which is why your smelling gas. Now you much determine if its smoking to much and your smelling to much gas. Try having a tune up done on the truck. Spark plugs, oil change, air filter change and if your still having those issues take it to a muffler shop and have them check the catalic converter

Is your engine turning over when u turn the key on? If the engine is turning over (also called 'cranking over'), then the battery is fine. If the battery loses it's charge while driving, then it would be the alternator, as that is what charges the battery. So, if your car won't start, but the engine cranks over, you have to check to see if there is spark at your spark plugs, if there is, u have to check to see if gas is getting to the spark plugs. Let me know what u find.