Easy question, search failed me. My front 15T sprocket has about 10000 miles and I noticed a slight hook to the tooth profile.
Can I flip the sprocket over to wear out the other side of the teeth or do I need a new sprocket? If it shouldn't be flipped over, why?

 

Don't flip it.
1 teeth will break
2 a new one is only $15
3 The Klx sprocket only goes on one way do to the offset.

 

And, Duh, your bike would only run in reverse!

 

If it is worn that bad odds are the chain is the same - worn out. It's time to save your nickles and dimes to buy a new front and rear sprocket and chain. Do it before the teeth turn to nubs.

 

Yeah.. and it'll only go in reverse!

 

With a sprocket that hooked, the odds are the chain is junk as is the rear sprocket. Run it a while longer so you can save your nickles and dimes to buy a new set. Putting a new sprocket on will not help the worn chain and will just wear out faster.

 

I just measured the length between 10 pins at being extremely close to 6.25", pushing down on the chain by hand to apply some tension. 2% "stretch" would be 6.375" so the chain is good, right? I have read that 2% stretch is a fair limit and mine is much less than that. And the rear sprocket tooth profile, on the bike, looks perfect. I see no change from normal tooth shape. I keep my chain fairly wet with 80W-90; as long as my rear sprocket looks good and chain stretch is <2% I intend to swap in new front sprockets when they first start showing noticeable wear. I ordered a new front sprocket and have parked the bike since posting my question until I install it. Also have a ring shaped magnet coming that sits on the oil filter, hope it was worth the small price.

 

The wear is due to a combination of dirt on rollers wear sprockets a bit and the small pin inside the link wearing (the "stretch" factor in chain) will allow the chain to cause wear on sprockets since it will no longer seat precisely in the sprocket, but rather it will scrub down into place wearing the sprocket. The reason why chain and sprockets should be replaced as a set. Even with a new sprocket the chain will not have proper seating since it already has the pin wear. Only a few will actually be tight, the others will be progressively out of contact inside the chain. That will promote both more rapid chain wear since all pins aren't pulling the load and sprocket wear since there will also only have a few links really loaded.

I know it sounds a bit complex, but with some mechanical thought you'll understand what I'm saying. It is the pin wear that causes the chain to lengthen.

So maybe it's worth sticking another sprocket on to get some more chain life. Take a good look at that rear sprocket, look close. Odds are unless it had been replaced before the chain, it will not have a symmetric U shape. It won't be as obvious as the front though.

But then unless you know different, it could be possible the rear sprocket and chain have been replaced and not the front sprocket or the chain replaced and not the front or rear sprocket. Some, like my late father, used to think that if there were teeth and the chain wasn't broke, it was all good.

 

Ahhh, I knew an old guy that used to add gasoline in a pan to 80w-90 gear lube and soak his chain in it. Theory being the gas thinned the oil which allowed it to soak inside the rollers (non 0-ring). Then the gas would evaporate leaving the thicker gear lube stuck inside the rollers.

 

I did a blend of 20W oil and STP. Put the chain in and put it up by the furnace where it was fairly warm. Did pretty good, but no where near an O-ring chain.