looks like the bottom has a collector for a 4v head. but its really hard to tell. thats why i guessed srx. the srx, sr500, and xt's are pretty much the same bottom ends. im not up on the xt's but youre right, looks like a converted dirtbike!!! which is bad assed. the sr had a rear disk and the mc for it was like 1" from where that one is mounted. and i see no reason for that to have had the bracket hacked, then moved to the other side of the frame tube, when it shouldnt have been in the way. that loop under the exhaust has me a little puzzled, but its still a rad bike. and yeah, i mentioned the srx didnt have a tube frame, but id bet the srx would fit the xt. that would be cool setup. too bad we cant see the other side.
someones got alot of yamaha parts though eh??