sprocket problem, need help urgently !

[stef]

I have been cleaning the bike over the weekend (95 m600), and while looking at the state of the front sprocket, i noticed a lot of carp behind it (like plastic bag wraps). So i took the sprocket off, not much problems there.
I am now trying to put it back in. now the fun begins.
The fit does not seem to be right.
-first of all, I cannot push the sprocket right back in its cavity.. should it go right back against the engine wall ? (of course, this is where i had all the gunk accumulated, so i didnt notice the gap.). the best i can do is clear the circular grove of the shaft by 3 to 4 millimeters. is that right ?
- next, there is the retaining plate problem. It looks as if it should be sitting just on the grove, see attached drawing, (although i have placed it a bit too far back, on the schematic). is that so ? and then the two bolts just bring the sprocket right onto the retaing plate, filling the marked 'gap' on the drawing.
It looks as if it should work, but the whole assembly looks a rather clumsy design.

am I missing a part somewhere ? I am trying to follow the haynes manual to the letter, but i have seen lada's better put together !

diagram here:
http://www.chez.com/sdavid/misc/IM1.jpg

[stef]

if the link does not work, it looks as if you may need to copy it in the address bar.

[Duncan]

The retaining plate sits in the groove in the shaft and the idea is it stops the sprocket from moving in or out. You slide it along the splined shaft till it sits in the groove then rotate it to align the tapped holes in the sprocket. The slots in the plate will then be misaligned preventing the sprocket coming off. This is common practice and because theres little side loading on a sprocket it works well usually.

If the sprocket ran on the seal it would tear it to bits so there has to be a gap behind it.

Its a good idea if the washer is damaged to replace this as you dont want the sprocket coming off and I also clean and loctite the screws in place.

[crust]

first off, put some grease on the splines of the shaft, because as you accelerate and slow down the sprocket is pushed and pulled on the shaft.

If the splines wear,its a full engine strip and new output shaft time, ouch, there goes the bank balance.

You are on the right track, the sprocket does not go all the way back. Slide it on, then put the retaining plate in the groove,line the holes up and try to pull the sprocket off.

It wont, cos when the holes line up the cut-outs in the sprocket and plate wont line up. Thats what keeps the sprocket in place.

check you have the sprocket the right way round, if there is a boss on one side. Dunno about the 600s. Do the bolts up nice and tight.

Job done.

:) Crust

D'oh beaten by Duncan quick fingers

[A Yerbury]

prev owner had no plate in mine so was equally ??? when I put mine on. As Dunc says it looks wrong but its right.
Alex

[stef]

just finished the job as you confirmed.. Shaft doesnt look worn.
the sprocket should stay there, as you said, there is little force sideways.
Still, it feels clumsy. if i grab the sprocket between my finger, i can actually move the thing by a couple of mm without any effort. that's the bit that's scary !
If the whole things starts wobling at 80mph (on a private road !) I would be worried of heating from friction. There would be little the two bolts could stop. I would be much more reassured it the whole thing was tight.
But this is probably why i dont design motorbikes !

[Duncan]

I can confirm theyre OK to 130mph so dont panic Mr Mannering.

A bit of float is probabaly a good thing to take up chain misalignment and wear etc.

[stef]

ok, I am sure mr Ducati knows far more about designing sprockets that i ever will.
If they are all like this, he meant it to be this way.
Thanks guys !

[Will]

How did all those fish get behind the sprocket? - the mind boggles!

[stef]

I'll ask my tuner...
(i'll get me coat)