First, I will tell you all a story then I will ask the question.

Therefore, I rode to work yesterday, which is a 15-mile trip one-way. Everything was fine with the bike. Then came the trip home after a long workday I decided to take the long way home and cut across the drop zone, which I have done many times in the past. There are a lot of nice big sand jumps I hit. So when I was jumping around I noticed a pop every time I went up the jump. The pop sound only happened when I put a lot of torque on the back tire. So I did what everyone would have done in this situation and stopped the bike and gave it all a once over. The bike looked fine until I got to the front sprocket. The sprocket was sitting in just the right position so that I could notice that there was one tooth missing…… yep I said it there was a tooth broken off the front sprocket. I hopped back on the bike and did the putt putt thing all the way home. When I got home, I took a better look at the situation. Well it wasn’t just one tooth it was two of them and they were right next to each other. The ride home was fine but I really babied the thing.

MY question is obvious now!! What the heck happened?? I didn’t even hear anything or feel them breaking off. What would have caused two teeth on the front sprocket to snap off like that??

This happened yesterday so when I get home to change the sprocket out since I have a spare 13 tooth I will take pictures so you all can see it.

 

Not to mention that I caint spell Broken... sorry...

 

is that the stock sprocket that you broke teeth off? im guessing it was just a faulty sprocket, i would think it would take alot to break off teeth on that sprocket.... throw the 13t on and keep goin...

 

No. It was a 13 tooth that I got from sdunn. It was new in the package from I think CNC sprockets... But like you said,,, I plan on throwing the one I have on and just driving on..

 

GT,

Since you brought the name up, have you heard anything from him lately?

I know he was buying an MX bike, and I think he mentioned the wife was with child.

How are things going for him?

 

How many miles on this chain sproket combo? Have you been looking ,checking for wear, it may have been wearing for sometime. On my other dirt bikes the front c/s wears and is not as easy to keep an eye on. We had a guy on the WR450F return from a ride and half the chain was broken on the inside link.Didn't catch it till after a 100+ up to 60mph ride. scary.

 

First, I havent heard from him since he said he's farwell to all of us.. He just kinda took off and didn't look back. I still have his phone number but havent called him. Maybe I will and give you guys all an update on him.

About the chain and sprocket combo. I have been looking for wear and tear but the sprocket looked fine. However, with the chain I have noticed that I have to keep moving my back tire to the rear more and more. The chain is getting longer. I put the chain and sprocket on at the same time about 800 and some change miles ago. I wouldnt think that the sprocket and chain would get bad that fast would it.

 

Bork Bork Bork! Sorry, just pokin fun... The spelling in the title reminded me of the Swedish chef on the muppets...
Speaking of the Swedish chef... This is hilarious.

http://www.google.com/intl/xx-bork/

 

All I know -as you probably do as well- is the 13t sprocket puts a lot more strain on the chain due to decreased bend radius of the chain on that smaller cs sprocket size. Maybe the chain stretch played a part in the sprocket's demise? Seems like the more the chain is stretched, the more strain you put on each tooth of the sprocket because the links aren't at the same spacing anymore. Add that to the already increased strain of going to 13t and you have a perfect recipe for material failure.

 

I'm not familiar with the CNC front sprocket. Does it have the shoulder on the inside, like the stock KLX sprocket? If not, you will need to use a spacer to get proper alignment with the rear sprocket. Some of the cs sprockets being sold do not have the shoulder.