Will a 16t sprocket hit the cover?

[diablo250]

Hi. I got my 250 on wednesday and have since put almost 500 miles on it. This bike is a blast. Has anyone put a 16t sprocket on the front? I am wondering if it will clear the guard. If not, then 15t it is.

[ztrack157]

15 is your limit.

[Alex]

If you want to go taller still after putting on the 15, you can put a smaller sprocket on the rear; some folks use ones as small as 41.

[SteveL]

First this is not a criticism just an honest question. Why do you want to change the gearing?. On the European “freeway” we run 75 to 80 mph, 80 mph gives me approx 9K rpm which is right in the middle of the power band and gives reasonable acceleration. If I increased the gear ratio by changing to a 15 tooth front sprocket I drop to lower rpm for the same speed and need to change down to accelerate. The bike is not going to go any faster top speed as it does not have the power to do that around 100pmh max. So why.

Steve

[Racer x]

The 16 will fit the J model 15 is the limit for the first gen.

[almost40]

Mod the bike and it will pull a 14t/41t to 108mph (gps verified) Thats about 12500 rpm in 6th with the stock chain. No need to change the front sprocket at all.

[Viper-Byte]

I have a 15t and I prefer it over the stock 14t, my bike is not stock engine wise, so it has the power to pull and at 100khp sitting at 7krpm, she is happy to accelerate hard from there, I usually sit at about 130kph at 9krpm though. Just over all I prefer the 15t, I have not lost much noticeable acceleration, so that is fine and it makes 1st, 2nd and 3rd gears usable.

[diablo250]

Originally Posted by SteveL

First this is not a criticism just an honest question. Why do you want to change the gearing?. On the European “freeway” we run 75 to 80 mph, 80 mph gives me approx 9K rpm which is right in the middle of the power band and gives reasonable acceleration. If I increased the gear ratio by changing to a 15 tooth front sprocket I drop to lower rpm for the same speed and need to change down to accelerate. The bike is not going to go any faster top speed as it does not have the power to do that around 100pmh max. So why.

Steve

I am changing out the ratio because I would like to drop revs a bit at freeway speeds. I don't like being that high in the revs when I'm cruising. That said, the change is simply my preference

[diablo250]

I also shimmed my needles today and removed the snorkel. The bike feels great. No more laggy midrange. The choke seems to rev it really high though now with the needles raised. I'll get the sprocket this week and put it on.

[mxnello]

did same to my 09 along with shimming, snorkel removed, kleen air removed and FMF Apex slip-on. Much better than stock and looking into a 44 or 43 rear as well to lower revs in 6th. It still goes very good gear to gear, pulls well and each gear has a longer [breath]!

[TrueFaith]

Originally Posted by diablo250

I am changing out the ratio because I would like to drop revs a bit at freeway speeds. I don't like being that high in the revs when I'm cruising. That said, the change is simply my preference

You'll also appreciate the taller gearing in the lower gears. First and second are a lot more usable than stock.

[ShelbyOne]

Originally Posted by almost40

Mod the bike and it will pull a 14t/41t to 108mph (gps verified) Thats about 12500 rpm in 6th with the stock chain. No need to change the front sprocket at all.

Does anyone know how small you could go with the rear sprocket? (before you run out of adjustment with the factory chain?)
I like the idea of only changing one sprocket.

[anthonyonakawasaki]

i just put a 16 tooth counter sprocket on my 08 250 and it does fit rather well. i had to do some grinding on the inside of the sprocket cover (just the width of the chain and maybe a millimeter deep).

the acceleration feels much more natural. engine does not feel as buzzy in the lower gears and running an indicated 60 mph is revving 6k and 70 mph at 7k.

i used the jt brand that fits the 2007 model from denniskirk.com

[kkim]

welcome to ninjette, Anthony.

[xTKx]

Originally Posted by ShelbyOne

Does anyone know how small you could go with the rear sprocket? (before you run out of adjustment with the factory chain?)
I like the idea of only changing one sprocket.

Originally Posted by anthonyonakawasaki

i just put a 16 tooth counter sprocket on my 08 250 and it does fit rather well. i had to do some grinding on the inside of the sprocket cover (just the width of the chain and maybe a millimeter deep).

the acceleration feels much more natural. engine does not feel as buzzy in the lower gears and running an indicated 60 mph is revving 6k and 70 mph at 7k.

i used the jt brand that fits the 2007 model from denniskirk.com

Dave and Anthony, welcome to the boards!

Anyway, for me personally, I plan to do a front sprocket change (probably to 15T). I don't know how you guys are getting those RPM levels, but when my speedometer reads about 80 (so, compensating for the approximate 10% over compensation of the gauge my real speed being much closer to 72mph) I cruise at about 10k rpm. A majority of my ride is commuting to and from work...
My only question: will a 15T front sprocket upgrade affect the lower gears? If so how much and will it be completely noticeable? (Remember, I'm somewhat of a motorcycle mechanical noob).

[kkim]

Originally Posted by xTKx

will a 15T front sprocket upgrade affect the lower gears?

yes

[snowfish]

I actually just installed a 16T today. The chain does hit the cover so you'll have to grind the stock sprocket cover like anthony did or buy a different one. I was looking around and I saw the shinto-racing covers that look like they'll fit.

The reason I did it also is because I wanted to lower the RPMS on the freeway. I regularly cruise at around 10k going about 75mph. It just feels like it stresses the engine. I'm not too worried about the decrease in acceleration.

[CZroe]

I heard that you have to add or remove a link off the chain or something if you want proper tightness after going up to 16T. Perhaps not if you go down in the rear a lot, but with 16T in the front, you are probably getting a little extreme!

[Sailariel]

I put the 15T on because I wanted to go a little farther than 10 feet in 1st gear. I am not into wheelies and stunting. The bike is used primarily as a sports/touring bike. It does everything I require quite well, and gets excellent milage. My last two mods--Corbin seat and extendable mirrors, complete the package.

[VelvtRide]

Originally Posted by Sailariel

I put the 15T on because I wanted to go a little farther than 10 feet in 1st gear. I am not into wheelies and stunting. The bike is used primarily as a sports/touring bike. It does everything I require quite well, and gets excellent milage. My last two mods--Corbin seat and extendable mirrors, complete the package.

I went down to 41 in the rear and got much more than I was hoping for. I, like you, wanted more gear to rip.... hated having to shift so quickly. Now I can get all the way through the intersection before having to shift. Didn't lose any get up and go, either.

From what I understand, changing out the front sprocket puts more stress on the engine than modifying the rear. For every one you go up in the front it's like 3.5 in the rear. Much easier and better performance with changing out the rear, IMHO.

I used this gearingcommander.com for reference.

[Rayme]

I had a 16 tooth sprocket up front, I reverted back to 15 because I couldn't adjust the chain slack to specs. Check it out, you WANT a chain that isn't too tight.

[kkim]

Originally Posted by VelvtRide

From what I understand, changing out the front sprocket puts more stress on the engine than modifying the rear.e.

no, changing the front sprocket to a smaller one puts more stress on the chain, not the engine. gearing changes will have the same affect on the engine, no matter if you change out the front or the rear sprockets.

[CZroe]

Originally Posted by Rayme

I had a 16 tooth sprocket up front, I reverted back to 15 because I couldn't adjust the chain slack to specs. Check it out, you WANT a chain that isn't too tight.

It's a good time to change sprockets when your chain is due for replacement anyway, so you might wanna switch back then and just get a 107/108 link chain instead. Of course, it's easier to change the rear sprocket at the same time.