I'm a huge fan of the Yamaha triples, I have four in various states of build/disassembly.
Your 78 is a good year with the electronic ignition, the second gear fix is basically $0, pull a clip, reassemble, ride like you stole it.
Go here for info:
http://www.yamaha-triples.org/
go here to drool:
http://www.yamaha-triples.org/photos/photo-thumbnails.asp?albumid=120
He races in one vintage class or another
go here to see Gnarak's stuff. He's documented his Triumph fork swap as well as the rest of his cafe build.
http://www.yamaha-triples.org/photos/photo-main.asp?viewmember=57
There's a crap load of weight that can be taken off these, I've got one that's going to paint and power now that's probably in the 410 pound range and that's keeping the chubby stock cast rims. The OEM forks are HEAVY, swap them out for larger diameter newer forks. You'll be happy. I've seen one (in pictures) converted to chain drive in a very cool looking vintage style frame, if i remember correctly it was running at something like 345 pounds or something crazy like that.
Upgrades for power and handling are out there if you know what to look for;
-Swap on an 850 head. Far better flow at stock lift, responds very well to port work (doesn't need a lot) +.2 to compression
-Swap to 850 jugs and pistons. You end up at 826cc and IIRC +.6 compression (?)
-Carbs and exhaust headers from any Hinkley Triumph triple up to (but not including) the 595/955 engine are perfectly spaced.
The carbs are still CV but they are really head and shoulders above the OE Yamaha Hitachis, very tunable and more forgiving with pods filters. Have an exhaust shop change the flanges on the header and it's a slam dunk. The angles are right, it fits under the bike, clears the oil pot and weighs a lot less, never mind the fact that it's tuned far better than the Yamaha piece.
-It's fairly simple to swap on an XS1100 swing arm (or even just the pumpkin) for much better gearing for acceleration.
-Swap to a dual disc XS650 front rim for spokes
-Swap to one of several Virago rear wheels for spokes out back.
-Swap to a Virago swing arm for more length. Helps when you swap to shorter/beefier forks since they'll be less raked, you may want just a bit more wheelbase if you feel it's twitchy.
-Chain drive conversions are out there, at that point you can go crazy with your chassis. I've chatted with a kat who's running R6 suspension pieces in some brit frame (older spondon I think) and if I remember correctly he'll be in the 350 pound range and running close to 140hp.
I *think* pistons from an FJ1100/1200 will work (wrist pin dia. vs ring land height) with the appropriate sleeves, 1050ccs should be do-able. I've got the parts on hand here except for the sleeves and I'm going to give it a try probably this winter. LA Sleeve is happy to make the sleeves needed for the conversion and their prices aren't bad.
I know there's the Megacycle cam sets out there, they are very nice but $$$
Delta Cams in Washington state reground a set for my last 850 that really woke the bike up....and they're not $$$. I think with shipping I was into them for $120 welded up and reground from my OE sticks. I have 20k+ miles with no wear issues. Good stuff.
the Special and the Standard share almost all the chassis parts except triple clamps and forks so don't be shy about that Special.
You should buy it!
