I also have a 92 Vmax 4. Some things to chek out are as follows.
1. Clean the carbs the jets tend to get plugged if the machine has been sitting
2. Replace the plugs I use NGK iridium BR9IEX they are expensive but well worth the money
3. I always use Yamalube as this seems not to foul the plugs
4. I installed a primer and injection nozzels for each of the carbs the parts can be purchased at a Skidoo dealer as this brand uses a primer. After seven shots of gas from the primer with the enrichener turned on my machine will start with only one pull.
5. If you do get it to run and it only runs on two cylinders the crank could be out of time this tended to happen on 92's. To fix this problem the crank as to be retimed and welded (mine is)

Once you get the machine running you will probably have years of good service from the machine. One upgrad I did to my machine was to install a skid from a 96 600XT this gives you a better trail ride.

 

1st....Figure out if the sled has spark on all 4 cyl. Like already said, cleaning carbs is going to be a very good thing regardless of weather its directly related to the starting issue. I have owned a couple of these sleds..started with a 92 and am now building a custom 95 800. I have never had the sled hard to start (ever) unless their was a problem. The 92 was a beast all its own and had a few things that they changed in 93..many people will chage to the 93 specs. the pilot on a 92 is #50, and was changed to a #47.5, the main jet was changed as well. Depending on how far you want to go I will be happy to dig through all my files and get you any info you request. If the sled has spark...find out where the fuel system sits, is it flooding the sled, is it straving for fuel? I have encountered both problems. I spent a week chasing a problem and it turned out to be a bad o-ring on the seat and it allowed fuel to pass even though the needle and seat were working properly. I am not disagreeing with cleaning carbs...this should be done. But personaly i like to find the problem and then correct. Good luck. oh, I have all the manuals and lots of info on these sleds.If you need any thing, PM. me and I will get back to you as soon as possible

 

What you do with it depends how long it was stored improperly and where it was stored. If it sat for a long time the fuel in the carbs would have evaporated and you will probably have gunk in there.

How rough is the sled?

Carb cleaning is a must. When the carbs are off check the jetting like already posted, 47.5 pilots and 135 mains. If it's been sitting for a really long time I'd be removing and rinsing out the fuel tank, changing the carb fuel delievery lines, and checking the pulse lines.

Do a compression test. Don't worry so much about the actual reading but consistency is what you are looking for.

I doubt that your cranks would be out of phase unless the sled was piped and ran at 9000+ rpm.

Put in a new set of plugs, personally I run BR9ES solid caps and have never had an issue with them.

 

also when you have the carbs off ,make sure you check the fuel pumps ,making sure all the impulse lines are hooked up and good ,not brittle ,just like Canuck says

 

PS. I have tons of parts for that sled....Pilots,mains, cdi, you name it...its on a shelf in my garage. Can help if you need.