Need sprocket info

[JessyBee]

How many teeth come stock on a front sprocket for the 09 250r?

I was told to buy a +1 sprocket for the front of my bike, I went to cycle gear and they told me that stock was 16 teeth and a 17 didnt exist.

Is this information correct? Ive seen a couple places that say OEM is 15 teeth. Anyone know for sure?

Thanks!

[Alex]

Stock is 14 teeth, it's a common mod to bump it up to 15 teeth to lower revs a smidge on the highway. I don't think a 16-tooth will fit without modifications to the housing; if you want to go any taller it's a matter of going up to 15 in front, then coming down from the 45 in back. There's been at least one poster here that runs a 15/41 setup.

[Snake]

Stock is 14 teeth. One of the first and easiest mods is puting a 15t front sprocket. Makes highway riding much easier on the engine and does not affect acceleration much.

[silver_bullet]

Here's the one I ordered. It arrived in about 4 days. I can't tell you anything about the difference as the bike is tucked away in storage still. http://www.denniskirk.com/jsp/produc...d=8098515&mmy=

[Tripyn]

JessyBee, CG is wrong but they should be able to get the right one for you. JT makes the sprocket and it is a 15tooth. What changing it did for me? It lowered the RPM's while on the highway, so instead of screaming at 9000 RPM's it does so at about 8000. Some say it also makes shifting a little less as you get a little more out of all the gears.

Anyway, if CG can't get it, order it at the link above!

[Snake]

Here are some threads to read.

http://www.ninjette.org/forums/showthread.php?t=20320

http://www.ninjette.org/forums/showthread.php?t=16332

http://www.ninjette.org/forums/showthread.php?t=10479

[Alex]

It will lower revs, but not by 1000 rpm at highway speeds. Going from a 14 tooth to a 15 tooth changes the gearing by 14/15ths, so if the engine was turning 9000 RPM before at a certain speed, now it will turn 8400 RPM instead. There's a great site out there, www.gearingcommander.com, that lets you pick the type of bike and then play around with all of the ratios as much as you want to see the effects.

[Tripyn]

Originally Posted by Alex

It will lower revs, but not by 1000 rpm at highway speeds. Going from a 14 tooth to a 15 tooth changes the gearing by 14/15ths, so if the engine was turning 9000 RPM before at a certain speed, now it will turn 8400 RPM instead. There's a great site out there, www.gearingcommander.com, that lets you pick the type of bike and then play around with all of the ratios as much as you want to see the effects.

Alex, I swear her 08 (we traded it on the 09) was geared funny then. I rode it before and after and it was just shy of 1000 RPM. The really kooky thing, the 09 runs about 7-800 higher stock then the old one and the 15 tooth hardly dropped her highway RPM's at all.

I will read what you posted Snake, my goal was to lower the RPM's as all she does is highway riding. My girlfriends commute is about 120 miles a day-again, ALL higway.

JesseBee, my intention was not to highjack your thread....but thanks for the info guys!

[kkim]

some/a lot of 250s had/have tach/ignitor issues that cause them to read wrong.

regardless of what the tach is reading, a larger front sprocket will lower the engine rpm at a given speed in the same gear.

[Tripyn]

Originally Posted by kkim

some/a lot of 250s had/have tach/ignitor issues that cause them to read wrong.

regardless of what the tach is reading, a larger front sprocket will lower the engine rpm at a given speed in the same gear.

That would make sense, thanks kkim!

[Snake]

Tripyn you may want to check this thread out dealing with the tach issue and power loss.

http://www.ninjette.org/forums/showthread.php?t=21043

[Rayme]

I fitted a 16 tooth but removed it because the chain was too tight to my taste. I settled with a 15 tooth, for the money, it's a good upgrade, not alot of power lost and a little higher gearing. The highway limits here are 110 KMH and following more or less the speed I almost dropped 1000 rpm, which is good, a little less busy.

[JessyBee]

Thanks, I think Ive settled on a 15. :]

[JessyBee]

Rayme,

any tips oyu can give me on switching it out? Im gonna try it myself. Do I need a center stand or can it be done with out it?

Ive never done any work on my bike before, my first oil change is due and Im gonna do it myself. Am I taking on too much by changing the sprocket myself?

Any tips would be greatly appreciated. Thanks!

[250fan]

for the 15T....you just put it on and away you go....right? Do you need to shim it or align it?

[kkim]

Originally Posted by JessyBee

Rayme,

any tips oyu can give me on switching it out? Im gonna try it myself. Do I need a center stand or can it be done with out it?

Ive never done any work on my bike before, my first oil change is due and Im gonna do it myself. Am I taking on too much by changing the sprocket myself?

Any tips would be greatly appreciated. Thanks!

http://www.ninjette.org/forums/showthread.php?t=10273

[Rayme]

Originally Posted by JessyBee

Rayme,

any tips oyu can give me on switching it out? Im gonna try it myself. Do I need a center stand or can it be done with out it?

Ive never done any work on my bike before, my first oil change is due and Im gonna do it myself. Am I taking on too much by changing the sprocket myself?

Any tips would be greatly appreciated. Thanks!

I would recommend having an impact to remove the front sprocket nut, it made the job that much easier specialy if you are alone, it will get the nut out much faster. It's pretty tight from the factory and hard to remove unless you have a large breaker bar and a friend to hold the bike/rear brake. Just make just to "pre tension" the chain a bit to not shock it too much.

[Sailariel]

I am thinking about changing the stock 14T sprocket to a 15T. The Dennis Kirk catalog recommends changing out both sprockets and chain. That would come to $172.00US. My bike has 8500 miles on the clock and the sprockets and chain show no visible signs of wear. I would suspect that I could probably get away with just changing out the front sprocket with no bad effects. I know that on a bicycle, if you put a new chain on some worn chainrings that shifting is really compromised. The folks on this forum who changed to a 15---did you also replace the rear sprocket and chain?

[kkim]

I would say to just change the front sprocket for now just to get a feel of the changes it makes. If the chain and rear sprocket are worn enough to affect the front, you will be in for a new set anyway in the future.

In the meantime, play with gearing combos to suit your particular needs.... go up on the front... you may want to drop a few in the rear, too, if you do a lot of long distance travel on the bike.

Once you find a combination that works for you, then go out and buy a set of sprockets and a new chain, which I suspect will be awhile.

[Rayme]

Originally Posted by Sailariel

I am thinking about changing the stock 14T sprocket to a 15T. The Dennis Kirk catalog recommends changing out both sprockets and chain. That would come to $172.00US. My bike has 8500 miles on the clock and the sprockets and chain show no visible signs of wear. I would suspect that I could probably get away with just changing out the front sprocket with no bad effects. I know that on a bicycle, if you put a new chain on some worn chainrings that shifting is really compromised. The folks on this forum who changed to a 15---did you also replace the rear sprocket and chain?

My bike had very low miles when I changed it so I didn't bother.

[Alex]

If there are no visible signs of wear on the front sprocket, I wouldn't worry about changing it out as a preventative measure. It's unlikely wear on the chain will be greatly accelerated. Our ninjettes are quite easy on chains and sprockets, for reasons that we're all familiar with.

[Sailariel]

Thank you all for the good advice. Will order a 15T and take it from there.