This shall be a lesson to you about winterizing your bike.
Let's take it from the top. Drain that nasty ancient gas out of the tank AND out of the carburetor bowl(s). You want it completely gone, all of it. If you're lucky, you'll be able to use "carburetor & fuel injector cleaner" (the fuel additive, NOT the spray) to clean any new varnish out of the carburetor(s) after you get it running. You mix the stuff with the fresh, new gasoline you're going to pour into the tank next.
After (partially, let's NOT get ahead of ourselves) filling the tank with fresh new gasoline and part of a jug of carburetor & fuel injector cleaner (mix it at the manufacturer's suggested rate), start charging the battery with a battery charger. DO NOT "fast charge" it, let it charge up on slow charge. It'll take hours. Fast charging will boil the water out of the battery instead of letting it convert back into sulphuric acid, which it's SUPPOSED to be.
After the battery's fully charged, THEN see about rocking the bike back & forth while it's in about 2nd gear, clutch lever released. If you like, pull a spark plug & feel the piston with a longish copper wire or solder. Touch the top of the piston in that cylinder with your wire, then bend over your wire about 1/2" above the head. Pull the wire OUT, rock the bike, probe the piston again with your wire. If the bend is still 1/2" above the head, you're not moving the piston, the bike's motor doesn't look happy, and you have a lot more work ahead of you than you thought. If the bend is now resting on the head, or if it's lifted significantly above 1/2", then you ARE turning the motor over by rocking the bike. Very good sign.
Now before you do anything else, remove the air cleaner and clean the mouse nests out of it. While you're in there, look for any weep holes or air hoses running from it up to the carburetor(s). Check for wasp mud nests. I've had mud nests in air lines cost me hours before I found them - they like any opening between about 1/4" and 1/2" to lay their eggs in, sealing their eggs in with mud. Those mud plugs can make your bike run NASTY. Leave the air cleaner open - you'll see why in a moment.
When that's all cleaned out, peek at the oil. In fact, don't even look at it - it has condensate (water) in it from the winter. A crankcase breathes all winter, inhaling moisture-laden air. Crankcase gets cooler, that moisture settles on the cooling metal & water runs down into your oil where you don't want it. Change the oil out of hand. Now. At the VERY least, loosen the drain plug & drain off the quarter-cup that comes out first - water will tend to collect underneath all the oil (it's heavier), so it'll be in the first bit that comes out. Provided that you didn't crank the engine, of course, which stirs it all up into a colloidal milkshake that won't separate all summer. Yep, the oil pickup tube reaches to the BOTTOM of the oil (so it still gets some when it's running really low)... right to where the water settled over the winter.
Wheel the bike out to a shady spot outdoors (important!) where it won't tip over off its kickstand, and put the kickstand down. A double kickstand is best, or wood blocks that raise the rear wheel off the ground. A single kickstand will do, though, if you chock the rear wheel. The FRONT of the rear wheel. So it can't take off & nail your neighbor's prize rosebushes when you get the motor started. Remember, the clutch IS sticky right now.
Oh, yes - take the battery charger out there with you. You'll be needing it. Connect it back up to the battery & plug it into the long extension cord you also took out with you. Start charging again.
While it's acclimating to its shady spot, go buy a can of spray starting fluid. Don't get two cans, you won't need the second one, and they tend to lose pressure over the winter so it's useless to stock up.
When you get back from the store, you're about ready, Shoo any wasps away from your air cleaner (we already talked about them) and try cranking the bike. If you get no fire fairly immediately (within ten seconds of cranking), stop and let the starter cool down while you retrieve your can of starting fluid from the truck. Let it cool down a little more - a couple of minutes - then spray a LITTLE starting fluid into the intake, where the air filter was when the air cleaner cover was on. You want it to go pretty directly to the carburetor(s). DO NOT shoot a whole lot in there unless you feel comfortable cleaning up an exploded engine. Immediately (within less than one second) after shooting in the starting fluid, crank it again. If you're lucky, it'll fire a little. Shoot in a LITTLE more & crank it again. Sometime in here you'll be closing (you close a choke to start a cold engine, open it to run a warm engine) your choke as you start to crank.
Be sure to let the starter motor cool off periodically - extended cranking is VERY bad for starter motors. The hotter they get, the longer they need to cool down afterwards.
At some point, it'll actually begin to run a little. At this point, you should probably back off on the starting fluid and close up the air cleaner again - it's starting to use gasoline. Close the choke fully & keep it that way until you can get it to run for fifteen seconds or longer - then you can fiddle with it like you usually do when you're starting that bike.
Keep after the crank-fire-idle-die-cool off-crank pattern until you can get it to idle fairly consistently for a fair length of time. DO NOT try to get it to run past an idle. It's not ready for that yet - the carburetor & fuel injector cleaner hasn't done its job yet, so the carburetor's mix is leaner than it should be for right now, so it'll run too hot for higher RPMs.
You want to get it to IDLE, and stay IDLING, for an extended time. During this time, you should expect it to smoke like a brush fire. That's the piston rings, which have rusted in place over the winter. Idling will gradually loosen them up so they seat against the cylinder walls again. That cloud of smoke is why we brought it outdoors.
Idle it, smoking like a demon, for at least half an hour. If you run out of gas, put more in... mixed with more of the same jug of carburetor & fuel injector cleaner, still at the label's mix rate. If after half an hour it's still smoking badly, idle it for ANOTHER half hour. Soon the smoke will clear - it'll be a gradual thing, but it WILL clear. You may not even notice the difference for a while.
Take advantage of that first half-hour making yourself feel useful by tinkering with that clutch cable. Get it adjusted up the way it's supposed to be. Tinker too with all the other little piddling things you didn't tend to last year 'cause you were too busy riding. Make a list of the stuff you broke off and intend to replace.
By the way... neutral has nothing to do with the clutch. Neutral is just where none of the gears are in mesh with each other. The clutch is fully engaged in neutral just like it is in any other gear position.
Once the smoking has cleared up pretty well (it'll probably still smoke a little for the first several hours of running), go apologize to your neighbors for making the 'hood look like something out of a Cheech & Chong movie. Come back & put some more gas-C&CC mix into the tank.
At THIS point you can think about revving it up a bit. Expect it to stumble. The C&CC won't have finished its job until you've run at least five gallons of gas-C&CC through. Go ahead & toy with the throttle. Remember that sound? Yeah. You're going to save it.
Until you've burned at least five gallons of gas-C&CC, take it a bit easy on the bike and don't ride anywhere alone. If it stalls out & you can't start it, it's a long, long push home.
Keep mixing C&CC with the gas until you've burned at least TEN total gallons. Varnish doesn't wash off immediately, it has to dissolve slowly unless it's being done in a carburetor dip tank or pressure-sprayed on the bench.
