If the price is right.. then, well, I have a disease that can be summed up with simply: "dooo it".
I'm a new TW owner as well, so take this with a grain of whatever you like grains of. Beware:
long-winded-and-bored-on-my-lunch-break reply ahead:
Make sure it has good tires on it--seems to be the item that costs the most to replace on a TW.
The ignition sounds like a reasonably easy fix if you can find one--someone on the board may have
a parts bike with that item, otherwise I'm sure yamaha will be happy to sell you one.. in fact,
stadiumyamaha.com lists one ('2GK-82501-01-00') for $113.17, and a new gas cap ('48Y-24602-00-00')
for $76.01. I am, however, not sure how you'd get these two items keyed alike.
They also list the side covers; but some are backordered, etc. I'm more inclined to say someone
may have a good set of plastics for sale on the board, I've heard they're compatible between
all or nearly all models; so its finding a color combination you like.
As far as the ignition goes, if they replaced it with a switch: figure out what else they've done
to the wiring harness that may or may not be reversible. Look for electrical tape and crimp
connectors.
Look at how far adjusted out the brakes are; it seems to be a good sign on how much life you'll get
out of them. Mine felt ok, but were adjusted almost all the way out, so they're pretty much ready
to be replaced.
Look at the chain and sprockets. Make special note of whether the previous owner(s) have replaced
the chain with an o-ring one (certainly a good thing), and how worn/rolled the sprocket teeth are.
My '97 is certainly not "cold blooded", so I'm inclined to agree with you that the carb is probably
dirty, and maybe the gas in the tank is aging a bit.. How exactly is the previous owner putting gas
in it with no key for the cap? If you can get the cap off.. does it smell varnished inside?
They're pretty simple with a fairly light aftermarket, so the likelihood that someone botched the
installation of an aftermarket component is pretty minimal; only the OEM ones that fail, which
I've also noted seems rare
Again -- if the price is right (including all obvious repairs), then don't let me stop you.
I'm a new TW owner as well, so take this with a grain of whatever you like grains of. Beware:
long-winded-and-bored-on-my-lunch-break reply ahead:
Make sure it has good tires on it--seems to be the item that costs the most to replace on a TW.
The ignition sounds like a reasonably easy fix if you can find one--someone on the board may have
a parts bike with that item, otherwise I'm sure yamaha will be happy to sell you one.. in fact,
stadiumyamaha.com lists one ('2GK-82501-01-00') for $113.17, and a new gas cap ('48Y-24602-00-00')
for $76.01. I am, however, not sure how you'd get these two items keyed alike.
They also list the side covers; but some are backordered, etc. I'm more inclined to say someone
may have a good set of plastics for sale on the board, I've heard they're compatible between
all or nearly all models; so its finding a color combination you like.
As far as the ignition goes, if they replaced it with a switch: figure out what else they've done
to the wiring harness that may or may not be reversible. Look for electrical tape and crimp
connectors.
Look at how far adjusted out the brakes are; it seems to be a good sign on how much life you'll get
out of them. Mine felt ok, but were adjusted almost all the way out, so they're pretty much ready
to be replaced.
Look at the chain and sprockets. Make special note of whether the previous owner(s) have replaced
the chain with an o-ring one (certainly a good thing), and how worn/rolled the sprocket teeth are.
My '97 is certainly not "cold blooded", so I'm inclined to agree with you that the carb is probably
dirty, and maybe the gas in the tank is aging a bit.. How exactly is the previous owner putting gas
in it with no key for the cap? If you can get the cap off.. does it smell varnished inside?
They're pretty simple with a fairly light aftermarket, so the likelihood that someone botched the
installation of an aftermarket component is pretty minimal; only the OEM ones that fail, which
I've also noted seems rare

Again -- if the price is right (including all obvious repairs), then don't let me stop you.