I've tried searching with no luck, does anyone know at what mileage to change out a front and rear sprocket? Does the front sprocket last longer if it's stock 17t? I'm at 18k miles on front sprocket.

That depends on sprocket material and chain maintenance. The stock front seems to be the best option as I heard the 16 makes the chain makes a clunk sometimes and I would say that is chain wear to me.

Look at the teeth. are they hooked? Are they skinny? Do the bottoms between the teeth appear to be too wide and out of round(the valleys should be perfectly circular when new)? Are there any broken teeth?

Those are all signs of ware.

A 17 tooth should last about 1/17th longer than a 16 tooth (lol). A 16 tooth will make a whining noise at certain rpm. My aftermarket 17 tooth wines a little. Barely noticeable. The OEM or Zephyr sprocket with the rubber hockey puck center is very quiet. Heavy for such a small part though.

You will most likely need to change both and then I would change the chain too.

Rook:

Why does a "hooked" sprocket tooth indicate a replacement is needed? I'm not arguing the point, and I agree that it *does* indicate a need for replacement (along with other sprockets and chain, the whole kit 'n kaboodle).

I just dont understand why? What is it about the teeth being "hooked" that indicates "I should fix this"?

From what I understand the chain doesn't come off the roller clean and puts pressure on them causing wear, thats the way it was explained to me in a laymans kinds way, ROOK help us both out here.

all I can do is offer my opinion and thoughts and what I have heard others say. We have actual experts on here that can give a scientific explanation. I'm not positive on this one but here goes. I think I recall hearing about the circle saw blade hook shape sprocket tooth phenomenon. It isn't normal ware. If I'm not mistaken, that is an indication of keeping a chain too tight? Normal wear will look like the troughs are getting wider and deeper like a letter U shape more than there circlular shape when brand new. IOWs, normal wear happens both on the front and the back of the troughs between teeth.

...but we need an expert opinion on this. Main thing is we know it's getting time to change that final drive.

Do you think maybe you keep your chain too tight? I know I have in the past but I've gotten in the habit of keeping it pretty slack. When I measure the slack, I don't don't pull real hard on the chain. You can pull an extra quarter inch or more in either direction if you pull to much. I use just about 3 lbs of pressure to measure the chain slack, no more than that. I can see a droop in the chain with the bike parked and carrying no additional weight. If it gets too loose, it feels sloppy when I'm on and off the gas.

I measure like this. Add the measurement from top and bottom run....one important thing, my chain slack measures about a quarter inch tighter on the ground rather than lifted on a rear stand. Never thought it would matter that much but a quarter inch is a lot when you consider the spec is 1.3"~1.5".

http://www.zx14ninjaforum.com/messages.cfm?threadid=6AE7FFEE-D56B-84E2-15072A3BDDB69729

Chain and sprocket replacement isn't a matter of mileage, it's a matter of wear and service life. Proper maintenance and lubrication will extend a driveline's life many thousands of miles. Conventional wisdom has the chain and sprockets being replaced as a unit, and you really can't go wrong doing that, but sometimes an individual component (like an aluminum rear sprocket) will wear out before the others and will require replacement even though the other parts are fine. Your manual will give a service life length for a certain number of chain links beyond which the chain should be replaced. Replacing the rear sprocket at the same time is a good idea, although front sprockets can last twice as long as the other parts. Check your chain length and rear sprocket teeth and you'll be able to see when replacement becomes necessary.

* Last updated by: Danno on 2/13/2014 @ 6:21 AM *

I change ONLY my rear sprocket last season. IDK if it was just the sprocket or if this how it goes but I needed to adjust my chain slack very often....like every 500 miles. When the adjustment reached the same mark on the swimg arm as where the previous parts were worn in to, the chain slack stopped needing frequent adjustment. Seems to me the new rear sprocket wore in prematurely to fit the old pattern. So now I got a new rear sprocket that is just as worn as the old sprocket. Not bad, but a waste. oh well. chains cost a lot and are hard to install, rear sprockets are cheap and easy.

Both sprockets old and new are aluminum. The old one lasted me about 20,000 miles and still in ok condition.

* Last updated by: Rook on 2/13/2014 @ 11:35 AM *

Eight months later. Now my turn.

Why does a "hooked" sprocket tooth indicate a replacement is needed? I'm not arguing the point, and I agree that it *does* indicate a need for replacement (along with other sprockets and chain, the whole kit 'n kaboodle).

My output sprocket is not wearing evenly on both sides of the teeth. I feel a hook near the bottom of the trough on the side of the tooth that pulls during acceleration. You can see the top of the teeth are rounded (sawtoothed) on the opposite side. From some older pics, it looks like my OEM sprocket had a similar wear pattern.

Is this a sign of running the chain too loose? The sprocket and chain have been in service 20,000 miles. The rear sprocket was changed about 10.000 miles ago.

The service manual indicates that A is a worn engine sprocket. My engine sprocket looks like B but that is suppossed to be a worn rear sprocket.

* Last updated by: Rook on 10/14/2014 @ 8:17 PM *

1. Think of a tree in the wind. Where that tree grew at a 20 degree angle from the wind.
2. Metal moves like a mud slide, the cutting of metal with a micro-lens shows how that metal can be pushed to mimic a moving amount of mass that sheers off as if watching a mountain side drop off its face. Look at that same tree angle by the tugging of that one direction.
3. There's no real metal lost but metal movement or that one side of the tooth being elongated.

My front sprockets wore from the leading edge and the trough.The backside was almost normal...but NO flat on the top of the tooth.My rears wore evenly on leading and trailing edges,with the top flat wearing smaller.So I don't get that picture at all...I mean...what they say is A and B and their corresponding sprocket.They're showing a 'hook'(kind of) angling backwards...and one angling forward.Yet no sign of trough wear making the teeth actually thinner.Mine had trough wear as well.Rook and I had the same type of wear seemingly happening.What would explain ours?I'm guessing the trough was wearing quicker than the tooth vertical surface.

I think maybe they just showed the shaping(wear) going on...and the need for replacement if it started looking like that?

This shape was my front sprockets.The rears were evenly worn both front and rear edgesAny ideas what would cause this wear pattern?

* Last updated by: Grn14 on 10/14/2014 @ 11:14 PM *

I think maybe they (KAWASKI)just showed the shaping(wear) going on...and the need for replacement if it started looking like that?

Rook and I had the same type of wear seemingly happening.What would explain ours?

Thanks HUb and Grn.

Grn, is that a ZX-14r engine sprocket in your pic? Not the same as my 08.

* Last updated by: Rook on 10/15/2014 @ 8:05 AM *

LOL!!!God NO!Only for teaching purposes ONLY!!!!And your take on the 'translation'...yeah...exactly what I thought;)Funny they didn't address this 'possible' mixup by now.(if it IS a misprint)...nobody's chiming in to confirm or not about theirs;)

* Last updated by: Grn14 on 10/15/2014 @ 11:26 AM *

You probably need to check your chain stretch which is the measurement between a specific number of links, you'll have to remove the chain to do this. When a chain wears its length increases and it no longer fits between the sprocket teeth properly, one of the reasons the sprocket teeth curl over. If you replace your sprockets and use a worn chain it will eat the new sprocket pretty quickly. Old rule of thumb is to replace chain and sprockets as a complete set. You can find the chain specs and how to measure in the maintenance manual.

You probably need to check your chain stretch which is the measurement between a specific number of links, you'll have to remove the chain to do this.

If you replace your sprockets and use a worn chain it will eat the new sprocket pretty quickly.

You probably need to check your chain stretch which is the measurement between a specific number of links, you'll have to remove the chain to do this.

For argument sake, we have Joeblow Analretentive working on his bike. Is so by the book, he makes a check of the chain and grinds it off as per suggestion. What is the difference we find a hard rubber ball, a block of wood, a length of screwdriver length and load one side of the chain and take a measure of the rung that is tight and straight.

Didn't that say no need to remove a continuous link chain to check for stretch if you load the stretch even more and know the real pull, not all straight and hand pulled and now release and check now on a bench?

No offense, but who is going to be more accurate... Tension as if it's stretched in service or remove a high hp continuous link chain so it does not need to come off until it is out of spec?

The book says to remove the chain cover, add weight to the chain and measure at the top rung. That was a maintenance inspect and said nothing about removing the chain and bench test.

Replacing the rear sprocket at the same time is a good idea, although front sprockets can last twice as long as the other parts.

I find this observation extraordinary.

Realize that the counter shaft sprocket makes almost two and a half revolutions as the wheel sprocket. That translates to two times the wear since both members are loaded equally but have vastly different surface areas.

I find that when changing final drive ratios, from a wear standpoint, the advantage is to go up in rear sprocket teeth rather than dropping teeth at the counter shaft.

The book says to remove the chain cover, add weight to the chain and measure at the top rung. That was a maintenance inspect and said nothing about removing the chain and bench test.

I used the bottom run and measured at three different points. I don't recall there was much difference between any of the measurements.

Realize that the counter shaft sprocket makes almost two and a half revolutions as the wheel sprocket. That translates to two times the wear since both members are loaded equally but have vastly different surface areas.

I find that when changing final drive ratios, from a wear standpoint, the advantage is to go up in rear sprocket teeth rather than dropping teeth at the counter shaft.

Yeah, only advantage to going -1 on the front is that it is less weight than going +2 or +3 on the rear.

Hub, I stand corrected, I still think "old school" sometimes!

"old school," when we still used master links, was to remove the chain. The chain was laid on a flat surface, compressed, measurement taken, stretched, measurement taken and then compared. I haven't had to replace a chain in a long time. You are also correct in what the manual says about hanging a weight, reread the section myself.

Thank you for the correction!

YW, and I had a good time ribbing the 'ol skool. Old school is still valid if you can find it. You pull enough masters out to see the pin is destroyed on one side only. So that pin sheer has to be butted up against the other sheered part or your slack shows you'll grind right thru more pin and the weakest link is that one sheered thru pin.

That's why I roll the wheel back and forth to crunch into the hangups and now it's more grooved at the max stretch. I step on the bottom rung or inflate a basket ball on the bottom rung and roll the wheel back and forth... That's anal enough for me to check for stretch.

And most of the time seeing a pin in that condition is one rusted chain. Then, if you read the lube being gear oil, not a light lube like WD40 and no sticking power is what the owner's manual says. So for sure I'd put a tape measure on a WD'd chain a lot sooner than a gear or greased chain.

If Rook wants to go thru chain and sprocket with a sprocket cover cavity that dry and clean... We ready for 90w gear oil yet, Rook? I don't want to get started on the WDorks yet.

Okay...so I have a question..for Hub mainly...but anyone can of course speak up.This 'oil' thing...Oiling the chain.The manual says to do this...I've never done that.I figured the 'oil' would be way more likely to not last on one of these chains(zx14's).That's why I've used Chain Wax...for several years now.What really IS the advantage(if there is one)to using the oiling deal on these chains.The Chain Wax heats up as you ride...allowing it to flow.And it really doesn't fling off...I can tell you that.So pretty much it's always lubing the seals and such.What do YOU think?The most 'build up' has(on mine)occurred on the countershaft sprocket chain guide in there.When it gets 'built up'..it drips(slightly)from that guard and ends up on the floor...but doesn't interfere with anything.Your thoughts?

I'm not talking about..."spray it on lightly and forget it...just to do it"...but I clean my chain first very well...then apply hitting all links inside the plates and such.It lasts for several 200/400 mile rides(respraying as necessary).Then I clean the chain again...and start fresh.My last chain was still very serviceable...but I figured I'd do the 'replace everything' deal when I got a new rear/front sprocket.The chain was in very good shape.Probably could have kept going for quite a while actually.

* Last updated by: Grn14 on 10/18/2014 @ 10:01 AM *

Like everything else, everyone has their own way of doing things. The fact that your are lubing your chain at all is a big plus. A good quality lube on the "inside" run of your chain will do wonders for making it last! Best to do it right after a ride while the chain is still warm.

Was at my local bike shop visiting with my friends when a guy came in and said his bike was "squeaking" and wanted it looked at. Service manager told me later his chain was so dry the bike, a 2012 Ninja 1000, was hard to push in to the service bay. Guess he never heard of chain lube!

The tacky spray is not going to thin out like gear lube. The carrier is going to evap before it has time to flow into the rollers/pins/etc. Whereas the gear oil is slow to move, but if we have a leak, you know oil will find a way thru that tiny crack and seep, not leak. The tack would not move like that. It's pretty much frozen and I doubt that kind of heat is going to move it or you'd have the oil whip off, right?

So if you went to the chain, you'd still see the same cling went nowhere is my guess. Cold, take a paper towel to the cling and that paper will not lift off that tack. Gear or grease, that wipes right off and can move/fling when in heat or due to centrifugal force.

Bottom line, you want that thin film of gear before the next lube. WD is so thin it will dry out sooner than grease or gear oil will.