The website was very-slow yesterday and not-accepting new posts, I had a long one addressing this, and I finally close-out without being able to post.
What I said was, call several Yamaha dealers by you and ask them what it would cost you to do what you want, i.e., have an operable bike to-ride, safely. My contention was, 'good-luck finding anyone even-willing to accept the job!' Why? Because it needs all parts of the bike to be addressed, if it's going to-be operable, and safe. My estimate was $2000+ in parts and labor, at which-point you've exceeded the value of the motorcycle. In today's market, probably by a factor of three!
Dealerships don't want to take on a job like this, only to-have the sticker-shocked owner abandon the bike once it's done. Even if they take title on a mechanic's lien that's another several hundred dollar expense to add-to the bill. Then they cannot sell it for what they have into-it, even with their wholesale pricing on parts and labor. That's why they don't want to take the job!
Sure, you might be-able to get the bike running, just-by cleaning the carbs, and using a jump-start, or a donor battery from another bike. That's what I would do, if it was something I bought for my 'willingness-to-pay' price. Just the bare-minimum needed to see that the engine runs, it doesn't have a bum starter, 2nd gear is OK, it doesn't overheat, the shift segment doesn't need replacement, and the valves don't need to be adjusted just to get it to start and to run. Hot-soak starts are accomplished. Now, to try a spin down the road, you need the tires to at-least hold air, hopefully they aren't showing cords! I've seen plenty of bikes riding-around with cords-showing, it's easy to-spot, especially if the bike you're watching is stopped and starts slowly, in traffic.
Now, you at-least need the front brakes to be working, for a test-ride. That may require a disassembly and cleaning of the front brake master cylinder, a flushing of the brake lines, possibly a disassembly and cleaning of the calipers, and re-assembly/ bleed of the system. That's pretty-much just time, if a thorough clean will get things back operational. I've found that probably half the time, a rebuild master cylinder kit doesn't work, now you've spent, what, $35? If the bike's been sitting for say, 3+ years, it's possible that the fluid has crystallized, maybe you can disassemble the master cylinder, clean it, and return it to service, without needing to rebuild it. That's something to try, before throwing-in a rebuild kit. If the master cyl. is truly-bad, and the piston is frozen into the bore, I'd bite the bullet and buy a new OEM master cylinder. They aren't cheap, but what's riding on them, expecting them to work faultlessly, every-time? Yes the complete master cylinders on ebay are tempting and cheap, I'll stick with OEM, thanks. ronayres.net for OEM front brake master cylinders is $134, complete, not including lever. Buy 12 washers for the hydraulic hoses, $2 each, prevent leaks on reassembly. Two at the master cyl banjo bolt. Five at the splitter, two each at the two calipers, and three spares for when others run and hide from your butterfingers. Throw some WD-40 or CRC 5-56 on the handlebar levers' pivot points, the brake foot pedal, and check the throttle for snapping-closed, smartly to closed-position. Same-for the choke enricheners, they need to close fully, you can 'eyeball' them, and if operating the choke lever doesn't close them fully, use a wand and shoot some lubricant on them, and work the choke lever up & down and watch to see that they all free-up, so now they both fully-open for starting, and fully-close for riding.
OK, let's say you got at least the front brakes done. Let's say the tires hold-air, and cords aren't showing. Let's say, you have the engine running, it doesn't overheat, and no issues to its starting, idling, and revving, stationary. Now you can try a spin around the block to check for shifting (fingers-crossed on NO 2nd gear issues). On the basis of this work, you should be able to determine what needs to be done, to be able to make a budget of expenses, and to proceed with returning a bike to the road, on-budget.
