Bad weekend

[rider250ex]

I had a race at thornwood mx this weekend. It was going good until i came down off of a table, hammered it and then this

http://i17.photobucket.com/albums/b75/dracutrider/Picture604.jpg

[08mxkfx]

im guessing your chain popped off? gotta keep it tight! that doesnt look so bad though. looks to me that jb weld will hold fine there just make sure to clean it real good before you do. And change your just in case you got some metal chips in there.

[rider250ex]

it was perfect. about an inch of play. i snapped all 4 of my rear sprocket bolts. I have no idea how that happends. i think i might have broken a few when i got tangled up in the first turn.

[08mxkfx]

oh that sucks!!

[bkquill]

ouch!

[mod440ex]

did you have acase saver on there, or was it the stock one? and was it the chain that did that?

[rider250ex]

Yup i had a case saver. It was the stock one, but no savers would have prevented that. The hole is actually from the head of one of the rear sprocket bolts that snapped off. Somehow it made its way up front and got behind the front sprocket. Its going to BCS performance next week to have new cases put on

[mod440ex]

wow that sux, did you bottom out when you jumped

[Claas900]

I'd bet your chain was way to tight. Get a tow strap wrap around your axle and sub frame and crank it down,your chain should never get over tight. remember the chain tightens and the rear compresses.

[rider250ex]

My chain had an inch of play with me sitting on the bike. My chain was not to tight. I got hit in the first corner and i bet someone hit the sprocket and broke at least one of the bolts. Then when i hit the table i got on it right as i was landing and thats what probably did it in.

[trextoo]

Wow! A little scared now. This is not the first case, have seen other posts on other sites very similar. When you repaired your ride did you use the stock Kawasaki sprockets bolts ? the second time.

They look very similar to the YFZ450 sprocket bolts, a little different setup because the hub on the yamaha does not have threads. The bad news is that Kawasaki uses an 8 mm thread and every other brand use 10 mm bolt with no threads (thru holes) in the sprocket hub.

I talked to all the axle makers, no one has a sprocket hub that does not use the stock bolts. Talked to RPM about making one, did not know about the problem.

If you dont want to thow a chain and have to replace a side case $$ the only solution is to upgrade to a hub with larger 10mm bolts!

Please call RPM or email him to encourage him to produce one.

[woodsZrider]

Originally posted by trextoo
Wow! A little scared now. This is not the first case, have seen other posts on other sites very similar. When you repaired your ride did you use the stock Kawasaki sprockets bolts ? the second time.

They look very similar to the YFZ450 sprocket bolts, a little different setup because the hub on the yamaha does not have threads. The bad news is that Kawasaki uses an 8 mm thread and every other brand use 10 mm bolt with no threads (thru holes) in the sprocket hub.

I talked to all the axle makers, no one has a sprocket hub that does not use the stock bolts. Talked to RPM about making one, did not know about the problem.

If you dont want to thow a chain and have to replace a side case $$ the only solution is to upgrade to a hub with larger 10mm bolts!

Please call RPM or email him to encourage him to produce one.


I'm not sure what you are talking about,,,
but if it helps me not to crack a case.....I'm all for it....

[trextoo]

The problem is under load (Racing/ sand dune riding) the rear sprocket bolts may shear (due to small bolt size/ load). The sprocket comes off the hub and the chain derails and hits the case. In some cases kawasaki will cover it, but in others they say it was abuse.

This will not always happen, but there is a high risk due to the design and bolt size used to attach the rear sprocket. Yamaha and honda avoided the issue with the larger bolt size or 6 bolts on the Banshee hubs.

[woodsZrider]

:eek: i see.....now i understand......

[DMS]

2 of my sprocket hub bolts broke at Wayne last weekend. I've read about others having ths problem. Lucky I noticed they were broke before I went out again.

I've had my rear sprocket off the quad 6x so I figured they were just over tightened one too many times by me. I change my gearing for the dunes.

Did you actually tighten yours to specs?

The dealer charged me $5 each for replacement hub bolts.

[wescaster]

i dont know much about the rear sprocket or bolt sizes, but i was wondering if someone actually makes the hub with 10 mm bolts will the sprockets have to be altered to work? i just dont have any experience working on these things but the new hub seems like a great idea and im sure whoever makes one will sell plenty.

[Claas900]

is there enough meat to drill the hub out to 10mm?

[wescaster]

If this is a big enough problem wouldnt or shouldnt kawasaki be coming up with a fix for us? it seems enough people are having this problem, and more want to avoid it.

[trextoo]

The stock sprocket has 10mm holes in it and the kawasaki bolts have a shoulder that is the 10mm and is stepped down to a 8mm thread.

I have ben told that many of the race teams have drilled out the stock hub. The hub does not have a lot of material in it to drill 10mm holes, so it should be a temporary fix at best.

As far as kawasaki goes it will take a lot of failures for them to consider it a big enough problem. The 2001 raptor had some trans issues and yamaha never recalled them, they only fixed it the next model year.

[wescaster]

hopefully someone will come out with an aftermarket hub sometime.

[Sprks450r04]

lonestar makes an aftermarket hub but im not sure if it uses the stock sprocket bolts

[rider250ex]

I have lonestars on my bike now. it uses stock bolts

[wescaster]

i saw a thread in the KTM section and it looks like they may end up having the same issue.

[pual0101]

anyone try going to fastenal or something and upgrading to a stronger bolt? This might be something i try before it fails

[Claas900]

mcmaster.com is a great place also,very fast shipping.

[Bajakawi]

I have to assume tha Kawi used an 8mm 10.9 bolt ..(10.9) in metric means the same as grade 8 in american...but i am not sure if they did..I would suggest to everyone to replace those sprocket bolts with the metric grade 8 bolts.

[4wheelinmatt]

Same thing happened to my rear sprocket. I went to the dealer and they called Kawasaki about it but they could never reach anyone to talk to about it. Kawasaki ended up never returning the dealers phone calls so i just replaced it all. I went back with the stock parts but im going to change out the bolts every few months to avoid another issue.

[RATPACK Z400]

If you cant change to 10mm bolt try changing grade of bolt like titanium or harden steel.