Welcome. After it's been sitting for 6 months (assuming you did not properly prepare it for storage), it's going to need a lot of things.
First off, it will need a new battery. No battery will last 6 months just sitting there.
I would change the oil before trying to start it, you don't need to change the filter with a new one, but I would remove it, and pour out all the old oil, and put it back on.
I would also clean the area around the plugs, remove the plugs, or at least one on each cylinder, and spray some WD40, or some 3 in 1 oil in the cylinders, and put the plugs back.
The tires will be flat, or close to it. You will need to inflate them to their proper pressure, check for cracks, and make sure the bead is properly seated all the way around. You may wind up having to replace the tires, but the ones on it should get it going.
I would remove the tank, pour out all the old gas, pour in about a gallon of new gas, shake the tank around real good for several minutes, then pour out that gas, reinstall the tank, put in another gallon of new gas, find a way of applying vacuum to the vacuum line from the petcock (without the engine running), and see if gas flows out the petcock. If it does, then reconnect the fuel line, open both carb drain screws, and see if gas drains out through the float bowl drains. If it does, you may be in luck. Close the drains.
With a new battery in place, and the choke on all the way, try and start it. If it starts with the choke on, let it run for a couple of minutes with the choke on, unless it starts to die, then move the choke partially off, and see if that helps. If it either won't start, or starts on full choke, but dies, your carbs are all gummed up. You can try removing the fuel lines from the petcock, draining the gas from the carbs, closing the drain screws, and filling the carbs full of Seafoam through the fuel lines, and let it soak for at least 24 hours. Drain out the Seafoam, close the drain screws, put the fuel lines back, and try starting it again. If it runs ok, great. Pour about 4 ounces of Seafoam into the gas tank, then fill it up.
If it still won't start, or starts but won't run right, you have little choice but to remove the carbs, take them apart, give them a thorough cleaning, and put them back on. If you do wind up having t clean the carbs, you will probably find a lot of brownish gunk in them. I use spray Gumout to clean carbs with. It may take 2 or 3 cans. You want them clean, especially considering how hard they are to remove and reinstall.
Hopefully, that should do it. If it doesn't, you have some other issues besides a gunked up fuel system.
Once the bike is running and ridable, give it a good cleaning and going over. Remove and clean, or replace the air filters, replace the spark plugs, change the oil and filter, change the coolant, remove the rear wheel and clean up any corrosion on the brake drum, or the brake assembly, check the brake shoes, replace if necessary, lube the pivot points with high temp grease, do a spline lube, (that is a job in itself), at this time you can decide whether the rear tire needs to be replaced or not, if it does, you might as well do it while the wheel is off. Drain and refill the final drive gearcase. Clean any rust or corrosion off the rear axle, and coat it with grease before reinstalling it.
Check the front brakes for proper operation, replace the pads if necessary, remove any rust from the rotors with steel wool and brake parts cleaner. Replace the brake fluid and bleed the brakes. Also check the condition of the brake hoses and make sure they are not cracked. If they are, plan on replacing them in the not too distant future. Check the condition of the front tire and replace if necessary. Make sure the fork seals aren't leaking. If they are, they will need to be replaced, but it's not a right now kind of thing.
Lubricate everything. The brake lever, the speedometer cable, the throttle cables, the choke cable, the rear brake cable and all linkage points, the carb linkage, the side and centerstand pivots, footpegs, spray all electrical connections and inside the handlebar switch housings with WD40. I'd also spray WD40 in the ignition switch and the fuel cap lock. Check the operation of the clutch and sidestand safety switches, they sometimes fail when not used for a long time. They can either be worked back and forth till they work again, replaced, or as I did, removed and thrown away.
That's about it except for the cosmetic stuff, It will probably need a good cleaning, actually, more like a thorough detail job. Remove any rust you find anywhere. Any threads that have a whitish look to them should be soaked in WD40.
I would ride it easy for the first couple hundred miles, change the oil and filter again, check the oil drain screen for any foreign particles, then consider it good to go.
Many will consider all this to be a bit excessive, but I am a motorcycle enthusiast, a mechanic, and a perfectionist. I love my bike, and keep it in top condition. But, I also ride it. A lot. I also had a little time on my hands, waiting for my oldest daughters 20th birthday party. And most of this can be used by almost anybody guilty of letting their bike sit for too long. Jerry.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
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1994 Yamaha XT225 parts bike