never seen that before

A recently-installed chain on the Tuono is whipping... sideways.

How did I find out? Well it's /just/ clipping the edge of the tyre,
fortunately just on the edge of the treads.There's a series of shallow
nibbles all round the tyre. Normal chain run is quite close to the
tyre, about 3-4mm, but I have to push the chain quite firmly across to
make it contact the tyre.

It ain't a bent back sprocket, for two reasons: the nibbles are all
round the tyre, not just one area, and I've checked the sprocket by
holding a pointer against the swing arm, that just brushes the
sprocket: it's even all the way round.

I haven't checked the front sprocket specifically for trueness but it
would have to be seriously bent to have this effect, and looked fine
when I installed it. It's a substantial machined item made by Renthal
with a wide splined hub - I doubt the problem's there.

I've double and triple checked the assembly against the Aprilia
workshop manual (strictly the RSV Mille one): it's correct. It's
impossible to get the left & right spacers wrong as they're identical.

I've double-checked the wheel alignment, that seems to be pretty much
spot on.

If I look along the chain line and spin the rear wheel then the chain
appears to snake slightly. At present the chain, a heavy-duty X-ring
jobbie, a Japanese make I've never heard of before (and can't remember
now), is the prime suspect.

Apart from this issue and a minor niggle with the LH mirror folding
back under hard acceleration above 70mph or so, the Tuono is huge,
huge, HUGE fun to ride.

 

My GSXR1100 is like that. It was close when new and rubs now.
My guess is that a modern Dunlop 180/55 tyre is a bit wider than
a 1990 Michelin 180/55. Perhaps I'll try a 170/60 next time.
Or I could offset the sprockets by turning the front sprocket over
and shimming the rear.