Carb modification.

[Baldphil]

I have an '83 that I purchased a couple years ago. It wasn't in the best of shape but I always wanted one of the first yamaha dressers.  after nearly 3 years, I'm finally getting it to run well. Carbs were a mess when I got it: leaked, not synced, clogged. Worked and worked but could never get them right. $600 for a professional cleaning and the guy said they would still need to be fiddled with a lot. I finally said screw it and ordered a carb modification kit from Germany. Now using a single pict 34 carb from a Volkswagen.  Wow! What a difference! Runs like a dream, with the added benefit of electric choke and fuel shut- off. Just took it on a 700 mile weekend run and averaged 45.9 mpg! I know there are some naysayers and purists that will disagree with doing it, but I've never been happier with this bike!

[Chaharly]

Have you checked spark plugs to see if you've got a lean condition? Depending on speed and wind, that kind of mileage seems a little too good to be true (not saying you're fibbing, just genuinely curious if the A/F mixture seems right). I might be interested in trying it if it can consistently pull good results like that.