It's a Yamaha, it's a big single, and it's totally off topic for a forum dedicated to Honda V-fours. But "anything goes", right? The story begins about 18 years ago. A friend of mine gifted me a 1983 Yamaha XT550. They look like this : That's almost exactly the paint scheme mine has, except in badly hand painted satin black rather than professionally done piano black. It also has a few "extras" compared to mine. Mudguards, for one. And side panels. Mirrors. Switchgear. Exhaust. Cables. Kickstarter. Side stand. Lights. And so on. This is what mine looks like, with bars from a dead 125 chucked on it so I can at least wheel it from one side of the garage to another : Now, I know you're all reeling from the stunning beauty I have unleashed, but there's more. The frame's a bit bent. Not much, but at least a bit. Whoopsie-doodles. So, what I have is - one (bent) rolling chassis, one motor, believed OK but hasn't run for at least 20 years, one set of carbs (minus the boots), one airbox, one knackered seat, one rusted-to-fuck tank, one set of exhaust headers, the essential electrics (CDI, reg/rect), ignition lock and key, most of the pegs 'n' ting and the title document. I chucked a couple of recovered tyres on it to save knackering the rims. I quite like XTs, mental wheelie machines, but this one is too far gone to contemplate a full restore. Plus the missing bits in "stock" form are all unobtanium. Which leads me to the idea of a "custom" build. On the cheap, of course. I am nothing if not cheap. Now, the ideal thing for a trail bike would be a "tracker" or "scrambler" build; unfortunately I think they all look like dogshit. And I already have an XT that looks like dogshit, see previous photo. I do, however, quite like cafe racers. Unfortunately, an XT is about as far from the optimum bike for cafe racering as can be imagined. But I've been playing about with dimensions, I think I can butcher the forks enough to get a decent stance on it, the rear subframe is easily chopped about, and I can unbend the front triangle - if I can find an 18" spoked rim to lace onto the front and a tank, I might be able to make something that looks a bit like this badly done potatochop: Tank's oversized on that. I tore down the carbs and cleaned them today, they're surprisingly alright. With pods and a funky zorst they'll need rejetting, of course, but they're good enough to see if I can make the engine go bang. I found an old kickstart lying about, came off a 250, doesn't fit on the shaft, obvs. I've bored out the mounting on the lathe, just need to cut some splines so it will fit. This is a stupid thing to do. I like stupid.
Tell a lie. I just found the carb boots. That makes life easier. Looking at the local ads, pairs of 17" spoked wheels with tyres go for around 50-60 roros, and that makes the rubber choice easier. 17" seems to be pretty much the standard size for supermoto, and there's loads of them things around here.
So, the kick I found was for a 15mm shaft. The Yam has an 18mm shaft. With an "unorthodox" mounting, due to the fact I have no 4-jaw chuck, it's been bored out (not, I might add, mounted like that), and splines cut. A tedious exercise.
Meanwhile, the forks are slammed, which was surprisingly easily done without cutting anything (and thus easily reversible). They have 3 springs - top out, initial compression, and main spring, plus an air chamber. By removing the super-soft initial compression spring, which is ~90mm long, and machining up a corresponding spacer for the damper rod, I've dropped the front (and reduced travel) by 90mm or so from the original 200mm, or 3 1/2 inches out of 8 for those playing along in archaic measures. This gets me a far more "sporty" stance / head angle, relacing the front hub to an 18" hoop will do the rest. As I've removed the softest bit of the suspension, this should stiffen the forks up fairly substantially, and the rest can be done by playing with air pressure, and potentially volume reducers in the air chamber. Can't be arsed to go out and take a photo, but before and after are as shown - reality appears to be playing along with potatochop simulations : Before : After losing the bars, slamming the forks, and going to 18" up front : The main worry I have at the moment is the reduced trail - the forks have a large offset, but it's at the end of the forks and not the triples, my calculations leave me with not much more than 60mm of trail, which is at the "extremely twitchy" end of things. If it turns out to be a massive problem, it can be resolved with new fork lowers (quite a few bikes of the period, for example the FZR600, had 38mm forks), or even a totally new set of forks. I also have to deal with the rear boinger, which requires stiffening and travel reduction, I have a cunning plan for this, despite the stock shock being monstrously long and not easily openable.
