If they have never been apart to your knowledge, I would get carb kits for em before tearing em apart. Once gaskets get to be about 7-8 years old they tend to lose there pliability and get brittle. Try a HEAVY shot of SEAFOAM and gas through the fuel system first though. Get a small tank and hook-up with 5 gallons of gas in it and about 1 quart of SEAFOAM in it, and I like to mix in some BERRYMAN CHEM-TOOL with it as well(about a pints worth). Run it for about 15 minutes and then let it sit for an hour. Then run it again for 15 minutes and let it sit overnight. Start it up the next day and see if it will idle. Best case scenario this will flush em out and you'll be good to go, worst case scenario it doesn't help your carbs but de-carbons the engine which it probably needs anyways and you have to build the carbs anyways.

I did exactly as Skools and Tsub said. It wouldn't hurt to replace the gaskets plus as Ferm said they get to where they stick and tear easily so it would be good to be prepared for that.

don't use a strong chemical on those carbs, Yamaha cautions soaking them in traditional carb cleaner as they have a clearcoat on the aluminum to seal up the porosity of the aluminum. I generally use Mercury power tune to clean out carbs, just spray it in a cup and soak out the little parts, fill the bowl after stripping the carb, and set the main body on the bowl just like it would be sitting if it was on the motor, after soaking, go back and spray some power tune thru the holes and blow them all out. Stay away from the welding tip cleaner, it will change the orfice size of anything it goes thru( I use the tip cleaner to fine tune quadrajet carbs). My wife kept complaining about the chemical smell from the garage after I rebuilt a set of carbs, so I took a hint from Yamaha, and bought a sonic cleaner from Harbour Freight. It works great, just tear the carb down, fill the cleaner with water and a splash of purple stuff, turn on the sonic and the heat, 15 min later its ready to be blown out and reassembled. The carb on the lawn mower picked up some crap the other day, I pulled it off, took it apart, threw it in the sonic cleaner(gaskets and all), two beers later, the mower was back running. The Harbour Freight cleaner isn't the best, but it works, I'm going to get a bigger comercial unit one of these days. With power tune at $9 a can, I've probably run at least 30 carbs thru the sonic cleaner, its paying for itself

I have done the whole carb thing on my 98 200 Yami, three times.
It`s not very dificut if you are a mechanic. If you are not, I suggest you take it to one.
The trick here is the floats on the bouls, if you don`t set them right, you WILL have problems, specially fuel leaks inside the engine and thats not safe.
If you decide to do it; you will need to prepare two screw drivers to remove the jets without damaging them. Also get a torch tip cleaning needle set from a welding supplies shop, this is a great tool for cleaning the jets.
Do not use strong solvents, this will damage the seals on the floats needle valves.
If you are carefull, you wont need a gasket set, but most of the time they break.
After you put the carbs together, make sure all the floats seal when upside down, and free flow when upright.
Make sure the carb to gasket to block seal/fit is perfect.
Make sure there are no fuel leaks from the fuel hoses ( engine running ).

sorry, I have to warn you guys again about the torch tip cleaner. It will change the orfice size of any of the holes you run it thru. WE had a Yamaha engine that was runing rough under load, everything checked out when we took the carbs apart. On the dyno, its was "fourstroking" trying to hit every other time under load, indicating a rich condition. We took the carbs apart and checked the jet size against teh book,it had the correct jets. It wasn't untill we found out the owner had receently rebuilt the carbs himself did we start a closer inspection. We compared the jets in his carb against another set of the same size and discovered his welding tip "cleaner trick" had opened up the main jets by a clear margin( you could easily see the difference without any visual aid). We repalced the jets with new ones from Yamaha, and the engine ran perfect. Welding tip cleaners are made to remove metal, I use them to open up air bleeds on Q Jet carbs(allways mike the reamer to make sure its the correct size). If you can't get the jets clean with cleaner(or teh sonic cleaner), then they are usually pitted and will need replacement as teh pits will affect fuel flow. If you happen to alter the jet size on purpose, remember to polish the jet openings to remove the swirl cutting marks left by a drill or ream as it will affect fuel flow as well. We use a tooth pickcovered with lapping compound in a biderectional drill, work it just like lapping valves

I have used the torch tip method all my life, and never ever had a problem.
The tip cleaning needles are not to be used as files, if you use them properly, they will not change the size of the jet by a measurable amount, unless you sit down and grind the hole of the jets on purpose. You can measure the needle with a micrometer, and insert the closest size for a jet, and only pass it once, just enough to clear the jet, and out.

this is why i refuse to run carbed engines anymore.

C-bone,
I remember when injection systems came out, on cars. BOOM !!! It was like majic, it was just too difficult for me to understand, It took me a while to swallow this technology. Today, I think it must be a LAW to install this F.I. gadget on every single thing that burns fuel.
I am waiting for my old Yami to "die", so I can get a FI one for my boat, but the SOAG don`t want to die just yet.

yep thats the thing with the old carbed engines, if you take care of them they last forever. I always liked FI engines, I guess learning troubleshooting on them makes it second nature.