I find it suits me best to ignore the order of the subassemblies suggested by Yamaha, and to construct them roughly in the order of final assembly. This way I don't have too many bits and pieces lying around, and I also find out about any fit problems sooner rather than later.
I did have quite a few problems with the model - these are described below, and also summarised here for convenience.
As usual I have reduced the model to half-size.
The engine went together pretty well, with everything fitting well and looking quite reasonable. There was only one minor glitch with the model - parts 9 and 10 were labelled the wrong way round compared with the assembly diagram and photos.
On the other hand, the cooling pipes linking the radiator to the engine caused several problems. Firstly, on each pipe five segments are grey, to match the engine and radiator, and two are black. This doesn't make sense to me, especially on the right-hand side (the larger diameter pipe), so I recoloured them all grey.
Secondly, on each pipe two of the segments (parts 38 and 39 on the left, 46 and 47 on the right) have a shallow angled join, but the angles are out of phase on the two pieces so that the result is straight. On the left it is fairly clear that the angle should be there, as it matches the angle on the adjacent part of the engine (part 13), so I assumed that this was the intent on both sides, and redrew the pieces to suit.
Finally, on the right-hand side the top of the pipe which enters the radiator ended up at an angle of some 30 degrees to the fore-and-aft axis of the cycle. To fit against the crosswise radiator it needs to be pretty much parallel to that axis. The problem was with the vertical pipe section (part 44) which only turns the pipe axis by about 60 degrees. I redrew it to 90 degrees, and things fitted reasonably well - the third photograph below shows the original pipe next to the corrected one.
No real problems, though as always the curved thin box-sections are difficult to construct twist-free. You can just see in the second photograph that the lower rear cross-beam is not parallel to the top one. It is really meant to be - the left-hand descender is significantly longer than the right-hand one.
I am not going to attach the kickstand yet, as it would be very vulnerable to clumsy handling. It will go on almost last.
Engine assembled with the frame. Yes the lower rear cross-beam is really meant to be wonky - the left-hand descender is significantly longer than the right-hand one.
Several of the components of this assembly are tricky to assemble, particularly the trailing arms themselves and the lower bracing piece on the left-hand side. This latter was particularly hard, being rather oddly developed with lots of small facets at strange angles. It came out rather twisted, but I was able to force it into position, albeit at the expense of some wrinkling at the rear end of the thin section.
You are not expected to cut out the openings and teeth on the chainwheel and sprocket, but it is not too difficult, and looks rather better than the printed detail.
This isn't my greatest triumph of modelling, but it will do.
Frame and rear arm assembled.
Small and pretty straightforward...
...and in place.
A bit of a struggle, with all the subtle curves.
There are a couple of problems here. It fits over the "Frame 2" assembly, but doesn't quite reach far enough to cover the white gluing area. Also the front wings of the saddle flare outwards, whereas the lands for the tabs which fix it to the blue cowling angle inwards (just visible in the photo below). Both of these mean that I shall have to make the fuel tank next, in order to have a trial fit before any further assembly.
Just two pieces, with the top overlapping the bottom most of the way round, so not as hard to close as I had been anticipating. The tank, seat cowl and frame do in fact seem to fit together well enough, so I can go ahead with the exhaust.
A feast of pipes twisting all over the place. I don't like the Yamaha system of putting two tiny tabs on one side of each join to fit inside the adjacent piece - I find it impossible to get things lined up and at predictable angles. I have adapted the inserts used by Greelt Peterusma on his Saturn F1 Rocket Engine to allow any angle of joint, and remove the tabs from the pipe segments. Here is the pattern for the inserts for the pipes from the engine to the exhaust manifold, the assembled parts for one pipe, and the completed pipe.
Yes, I know I have made only five joint inserts for six joints. This is because the third pipe segment (from the left) is very short, and the insert on its right-hand side goes right through to provide support for the left-hand joint. It isn't at the correct angle, but it still works well enough.
Many more pieces later, the complete exhaust put (mostly) together, but not glued yet.
Now for a big assembly session.
The state of play so far.
Very small, with just half a page of parts, but tricky. The slogan on the number plate is a bit naff, but I decided to grin and bear it.
A mixed bag, fiddly but manageable. The bars which hold the front forks apart (or together) are very thin boxes, and I didn't attempt to make them as designed. Instead I laminated the top and bottom to a piece of mounting board of the correct thickness, then wrapped the edging around the resulting solid lump. In the component pictures, the top caps for the fork tubes are missing - I left them off until the top stretcher bar was finally glued in place once the forks were fitted to the frame.
This took me two goes to get fairly right. The curves are quite subtle, and it is not altogether clear from the assembly diagram how things fit together. Throughout the model, valley folds are supposed to be marked by a dotted line, but by no means all are so marked, and this did lead to some difficulties here. I did get the first try reasonably together, but one or two false starts meant that it was untidy, and some of the thin sections were misshapen.
Quite a lot of the reverse side is going to be visible, so I have printed a mid grey on the back to tone it down.
I shall not fit this to the rest of the motorcycle until I have completed the Front Cowl so that I can be sure how they fit together. Clearances appear to be quite tight.
I didn't find the assembly diagram or photographs very clear as to how the main piece was to be folded and glued. Again the back of the paper is quite visible, so I coloured it a darkish grey on the body of the fairing and lighter on the windscreen.
I chose to join the two cowls first, before fixing them to the frame. It was quite a push to get the windscreen to fit to the top of the meter in the correct place, and I have produced rather a kink in the screen where they join. Fortunately it doesn't show very much in the photos.
A very sparse page of parts - only 17 small pieces - but a little complicated to assemble, at least for the right-hand side.
A real marathon, I struggled with these. First came the front tyre, in Yamaha's usual style - not too difficult, but I made a bit of a mess of putting on the tread. I left it for the moment, and put together the hub and spokes, only to find that they were almost a millimetre (in my 50% scale) too big to fit inside the wheel rim. I am used to having to squeeze the spokes a little to get them in, but this was just not on.
I put that on one side, and had a go at the rear wheel. Again the tyre gave no special problems (and I made a rather better job of it). This time, forewarned, I only made two spokes before trying things out. Once more they were significantly too long, and in addition the inner end was angled too steeply to fit against the 36 degree angle of the hub (10 facets).
Returning to the front, I estimated that I needed to reduce the spoke length by 5%, so printed off new spokes at 95% of the previous size, and a new full-sized hub. The made-up assembly fitted much better, but the fit against the hub was also not good (too shallow this time), and the leading edge of the head of each spoke, which should rest against the rim, was dangling free.
At this point I decided that I would have to recalculate the spoke patterns. I have a C++ program framework which allows me to do this relatively easily, so I got down to working out the geometric calculations. This took a while, so for light relief I made up a new front tyre. This time I messed up the joining of the rim halves, so I still didn't have a good tyre.
Eventually I ended up with a new spoke pattern. Here it is shown as an outline in red overlaid on the original part. The shortening is easily seen, as is the significant change to the leading (upper) part of the spoke head.
Making up three new spokes and attaching them to yet another hub showed that I was at last on track, but I still didn't have an acceptable tyre. I stripped the tread off the original attempt, and fitted a new one. It was better, but still not entirely satisfactory. At least now I could make up the complete wheel, but I avoided gluing the spokes to the rim pending a decision on the tyre.
Now came the rear spokes. I had written the calculating program to be parametrised in all relevant respects, so I just had to plug in the new measurements, to produce this:
Now I could make up the rear wheel (though I had to construct seven spokes to get five usable ones). Finally I stripped off the rim from my second attempt at the front tyre, attached a new one and added the tread, to come up at last with an acceptable front wheel. Here are the results, with most of the abortive attempts.
Final assembly.
In case anyone out there has similar problems with the spokes, here is a PDF file with the modified spokes which I used.