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16 Tooth front sprocket

27603 Views 118 Replies 36 Participants Last post by  AUDACIA
Hey everyone, just wanted to post a little more gearing information for those that might think about changing their sprockets to make a difference in their ride.

I primarily use my 250 as a mode of transportation to and from work. And that's 40 miles one way, all of which are on the highway. So for me, the stock gearing absolutely sucked. So I went the cheaper route first, and swapped the front 14 tooth for a 15 tooth. That made a nice difference. Especially since the internal gear ratios for first gear are so low, it would let this bike pull a small truck.

But always being on the highway screaming at 9000 RPM's... it was killing my fuel economy. So the 15 tooth was nice. I would reccomend it to anyone. I went from 55MPG up to 60MPG with this $13 mod. Well worth the money.

Then I wanted a little more, so I started on the rear. I went from a 45 tooth to a 43. That was a little better for me. Would let me cruise @ 65-70 mph at just over 7500 rpm, and fuel economy went from 60MPG to now averaging about 64-65mpg pretty consistently.

Then my parts guy, Joey, called me and told me that he could get me a 16 tooth front sprocket if I wanted it. I said sure, why not?

About 10 days later, it showed up in the mail.

So I decided to put it on. Which is where the challenges came up. Because that sprocket is SO BIG, that the countershaft cover wouldn't go back on once I had it all bolted on. So I had to take it off, and grind part of the cover away, in order to let the sprocket turn w/o grinding on the cover. (what I mean by grind some of it away, is where the chain came into contact with it when it was bolted back on. Not CUT part of it off per se.) So I just ground down a 2 inch line around the inside of it. You can't see it when it's bolted back on.
Not like it was difficult or anything, just took some time with a dremel and a cutting tool.


It took me several attempts at doing some grinding, then putting it back on to check clearances. But after the 4th or 5th time, I finally got it right, and the wheel would spin w/o the chain hitting anything.

So then it was time to ride.
Now, remember, I'm running +2 on the front, and -2 on the rear: that's a HUGE change.

First gear wasn't that different, again, because it's geared so low internally. But when you click from second to third... and so on.... HOLY SH!T what a difference. It's like my ZX6. You can pull each gear for a really long time.

So I left it that way for a few days. On any type of hill.... I fould myself having to click down a gear to keep my speed up. Then another gear..... and another gear.

It was just TOO tall for the little motor to pull w/ any type of authority.

So I pulled the back wheel off, and put the stock rear on, which left me with a 16T front, and a 45T rear.

And after having that on for the better part of 2 weeks, I am happy to post, that I am running a consistent 65MPG on the highway, and rolling @ 70mpg at between 6500 and 7000 RPM.

For me, this is the perfect gearing. It will pull myself with my girl on the back from a light w/o a hitch, and cruise up most gradual hills w/ not so much as a grunt.

Now mind you, I've also done the $36 exhaust mod, and shimmed the needles 0.010, removed the snorkle, and re-sync'd the carbs. So it ran pretty good before the gearing was done. But now....
I'd reccomend the 15T to anyone. And for anyone that does any touring, or long distance rides... you'd be happy with the 16T if you wanted.

Since nobody else seems to be able to get any sprockets for the 250, my parts guy's name is Joey, like I mentioned before. He can be reached @ 800-596-6199. Tell him Todd from Florida told you to call, (he's in Ohio) and he'll give you more information than you'll know what to do with... besides being able to get you anyting that you want. Including the VENTURA rear seat bags that nobody in Florida can seem to get either.

Anyhow... I hope everyone finds some use out of my gearing experimentation. And I'll try and answer any questions that come up.
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Thats great nice to hear, I do alot of highway traveling and was wondering about that myself when i finally get my 250 that will be one of the first mods i do besides, exhaust (duh) and fender eliminator (double duh).
joel said:
where can i find those sprockets?
I got mine from the dealership. Like 12 bucks or so. Cheap mod.
racerboy where in ohio is ur friend im from ohio in the dayton area does he have a shop?
When you used the 15/43 combination, did you have to do any modifications to the chain?
If you want the 15 or 16 front, call my parts guy "joey" He can be reached at 330-332-8534 or 800-596-6199. He and I worked together for a few years at Andrews Cycles in Salem, Ohio. He's still there, and is simply the parts "wizard".
Tell him that Todd from Florida sent you, and he'll make sure he hooks you up. He gets things really fast, and can have whatever you want at your doorstep lightning quick.
i definately am going to do this.....in a year or so when i get my bike lol
Hey, I just got my bike and I like fuel economy ..and will do the 15 sprocket front mod for sure.. but I will be doing 95% of my driving in the city..

Basicly it change the overall gearing right, so in situatio where I would need to be in 4th gear to climb a hill, I'd "possibly" have to use the 3rd after?
hi all.

My name is Sony from Indonesia. As for the front and rear sprockets, why don't you guys check the Driven Racing productswww.drivenracing.com. They have pretty good options for the sprockets size. Some of us here have already use it. Hope that helps.
Hey Sony, welcome, head over to the newbie section start a post and introduce yourself! Show us some pics of your beast.

Lots of indonesians on here now, I'm hoping to head over there to see some family next year.


Tweek said:
When you used the 15/43 combination, did you have to do any modifications to the chain?
Stock chain will work with 15/43 or 42 or 41 . and more probably
My spin. We all use these bikes for different things. I needed a high milage bike. I have 4 college buddies that needed the same. One of them has 2 brothers and his dad & they all have 250s. We tried several combinations of gears & this is what we found. First, we went directly to a 15 tooth sprocket & it made first gear seem more like a usable gear. We progressively went to smaller rear sprocket gearing & found 38 or 39 rear sprocket to work best. We have a few good grades to climb & it doesn't have any effect on climbing, for the exception of having to gear down. The gearing has spread the ratios out so each gear has more rpm in each one, and first gear is really usable. Our Milage is consistently above 70mpg with 78pmg being the best on long flat & steady speed of 65mph. Hard to beat that by any US vehicle. Also it dropped the rpm, on the highway 2000 revs. Other things we did, that made a HUGE difference, was to mod the suspension, both front & back. Once the mods are done, you simply could not go back to stock. I'll discuss al the suspension mods in another post soon.
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I just put a 16 tooth fron on mine (still stock rear) and I love it. I love it soo much I got pulled over.... luckily it was a motorcycle cop and he was really nice. He said he 'forgot' his ticket book back at the station and let me go with a warning. I said I would put it in my stocking as a Christmas present lol.

Anyway, the 16 tooth is really nice. I do 45-50 mph about 20-25 miles a day. I can do almost 50mph in first gear now (instead of 28ish), which is really nice when you are starting out in a turn; no need to worry about shifting in the middle of the corner. It doesn't really feel any slower, actually the power feels much more gradual and smooth than 'peaky' like it used to. I dont know how gas mileage is affected yet, but I'll post after my next fillup.
This sounds like my first mod ill do on my bike since i mainly commute on mine.

Will the 15 tooth sprocket in the front slow down acceleration off the line or will it increase it thats with the stock rear sprocket??

Does anybody have a instructions on how to install a new front sprocket?
Larger sprocket in the front, smaller in the rear DECREASES acceleration, but increases top speed (assuming you have the power to pull to red-line in every gear...).

Smaller sprocket in the front, larger in the rear INCREASES acceleration.

There really shouldn't be any instructions on how to install a sprocket.. Take off the chain guards, loosen up the chain, unbolt the front sprocket and install the new one.

RacerBoy said you have to modify the front sprocket guard because the diameter of the whole sprocket and chain is increased by a substantial amount.
nice alright thanks man..

hopefully it doesnt slow down the acceleration anymore than it already is.

Now i gotta find the sprocket :)
Well, both RacerBoy and Red said that it didn't affect first gear acceleration all that much (not enough to switch down a tooth at least), and Racer is still able to take off with his girlfriend on the back without a problem (something I was concerned about too... Although she only adds 110 lbs to the total weight, haha).

Let me know if you find the sprocket online somewhere. I looked last night and found someone on a different forum saying that they used the 16 tooth for the first gen's, but he was saying that other people were saying that it wouldn't work/would need a washer. He seemed to make it work, but I'm concerned about whether or not he'd know if it was correct or just a little sloppy...

Red, where'd you get yours?
do you have to replace the stock chain drive to be able mount a 16 sprocket because it doesnt work on my 2008 with 16 front and stock 45 need help please :-\
Both of the guys (RedRider and RacerBoy) said that they didn't have to get a new chain.. Just run the rear tire in as far as you can on the adjusters, it should be enough room to install it.
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