Noob front sprocket questions...

[grimmelkin]

Hi,
so I started having some vibrations and bad noises coming from the front sprocket on my zzr250, the chain was stiff in places so I bought front and rear sprockets and new chain to replace everything.
The teeth on the front sprocket are a little hooked and it definitely needed replacing but it looks like the inner splines/teeth that seat the front sprocket on the engine output shaft were worn because the sprocket had about 3-5mm of tilting movement (wobble...).
When I put the new sprocket on it is a nice tight fit over the end of the shaft but when pushed into position it has a small amount of movement in it, implying that their is some wear on the shaft..
Am I correct in assuming that the front sprocket should not have any wobble to it? (note this is a tilting movement not sliding along the shaft)
Google for wobbling front sprockets suggests this is normal at least for non genuine parts..

The replacement front sprocket I picked up is a non genuine part and appears to be about 1-2mm too narrow which is probably contributing to the wobble. It will also mean that there is a small gap behind the sprocket which can't be good.
The shop where I bought it is going to check on Monday to make sure it is the same size as the genuine kwaka part before I order the genuine one in. I am hoping it is just the non genuine parts are the wrong size and not my bike..
Has anyone ever come across this issue? All the ZZR250s use the same size sprocket so it seems strange that it is the wrong size given they have apparently sold plenty of that part over the years.. Is it supposed to have a gap?

many thanks in advance
jaz

[6maniac]

G'day jaz .... dealer ordered an after-market front sprocket for my ER-6 - it was too thick, so they used the Kawasaki part.

[MrWasabi]

Ive used after market front sprocket on my zzr when i had to change it, i dont recall it moving left and right even the slightest, it was a perfect fit. I picked mine up from MCA at the time.

[grimmelkin]

thanks,
I figure I'll just get the genuine part ordered in, it should be the right size which will reduce the amount of wobble that it's got...
jaz

[Gosling1]

1-2mm is not that excessive really - nothing to worry about. Once you lock the sprocket into position with the big nut, any slight amount of wobble will disappear anyway.

[grimmelkin]

1-2mm is not that excessive really - nothing to worry about. Once you lock the sprocket into position with the big nut, any slight amount of wobble will disappear anyway.

If it used a big nut I wouldn't be so worried but it uses a thin (2.5-3mm) retention plate that slots into a gap in the splines on the engine output shaft. Essentially holding the whole lot on by the teeth of the retention plate..
You can sort of see it here. Part 13270 on this fische http://images.cmsnl.com/img/partslists/transmission_bigkae0124e1361_6823.gif

The old retention plate is pretty worn so I've ordered a replacement one and the proper kwaka sprocket. Fingers crossed it'll be ok.

[Gosling1]

gotcha - I still don't think it will be a big issue anyway - the front sprocket does not have to cope with any lateral loadings (ie side to side along the splines) - so that retaining plate will do the job alright.

Unless you have a really large amount of freeplay with this front sprocket, I don't believe you are going to run into any problems.

[grimmelkin]

I know what you mean, it isn't going to be under any strain so it shouldn't be an issue. I guess it was just the amount of wobble on the old sprocket that made it seem like it was likely to just get worse with wear. In all likely hood the vibrations from the hooked teeth caused the additional lateral movement that caused it to wobble even further. New chain and sprockets should let everything run smoothly.
I do appreciate the re-assurance though, besides gluing fairings back together and changing a headlight this is the first work I've really done on the bike, I'm sort of just guessing for the most part..

Figured if I was going to have to wait to get the retention plate in I might as well get the kwaka sprocket too, it should fit properly and the extra width should help reduce the wobble. For the $30 difference for the kwaka part I'd feel like I right muppet if something went wrong.

[Gosling1]

It can't hurt to be a bit careful if this is the first time you have gotten into the guts of the bike - good on ya for having a lash mate, the more you learn about your bike, the more you will appreciate it. Good stuff !

[grimmelkin]

Thanks again for the advise, much appreciated.
Looks like I have to go with the aftermarket one, It is either that or 2-3 weeks of no bike and catching PT waiting for the part to come in. Kawasaki have no stock of the sprockets only the retention plate.
I made a couple of calls to see if anyone had any in stock, ended up speaking to a guy at brighton kawasaki who said the same thing as you, apparently no one really uses the genuine ones so kawasaki don't even hold it in stock.
Figure I'll just keep an eye on it over the next couple of weeks, make sure it isn't doing anything strange and see how it goes. Bike's only been out of action for a about a week and I'm already climbing the walls, don't think I'd last two more weeks...

[Gosling1]

I think the cost of OEM sprockets is what keeps the aftermarket sprockets in the market in the first place