So I decided to slap on a new chain and sprocket 'upgrade' on the Yibber as my old one was starting to sound a bit 'agricultural'.

The front sprocket was quite wibbly when I took it off, but the bolts were fully tight and the output shaft has no up/down movement so the bearings are fine.

Put the new sprocket on (used the old spacer) and it wobbles a fair bit still.

Made a rather tedious little video of it ... http://www.youtube.com/watch?v=DClzEvwxQj0&feature=youtu.be

Also took a photo of the bare shaft (oo-er)

It's a 2011 with only 5000-odd miles on it.

What ye think? Perfectly normal or potential fireball of doom?

Camera

GT-N7100

Focal Length

3.7mm

Aperture

f/2.6

Exposure

1/132s

ISO

80

hmm that does not bode well , is that the correct Gen yam sprocket for the bike.I know on the africa twin hondas some people have had problems with aftermarket sprockets being too loose and have worn the splines so badly they have needed to replace the shaft

I must admit that thought applied to me, if the thickness of the sprocket is a lot thinner than the groove in the shaft then I can only think that they are not a matched pair.

I hope this helps.

No I checked it and it's identical to the original Yamaha sprocket that was removed. Bear in mind, the Yamaha sprocket was doing this too.

I know the splines are a bit worn but would it cause that much lateral play in the fit? I'm wondering if maybe just chucking a spacer between the sprocket and the retainer to take out the lateral 'wiggle' would suffice?

of course it's loose, you can clearly see in the photo that shaft is worn to hell on one side of the splines !

That looks expensive

Looks fine to me - it's the same design as the Honda Cubs, they all wobble a bit to allow for movement in the chain, or something of that ilk. Suffice to say, millions of third world families have been transported by bikes with front sprockets just like this for over 50 years and I've never heard of one failing yet. The sprocket is held in place by the 'spacer', actually a locking tab, in conjunction with the two bolts - it ain't going anywhere as long as the bolts are done up properly.

Don't worry about it and just ride the bloody thing!