Install a 16 Tooth Front Sprocket
 

This is fairly simple process. It actually took more time to reinstall the friggin' cotter pin than anything else.

Things you'll need:

17mm wrench
3/4" wrench
12mm socket
7mm socket
30mm socket (torque wrench)
alligator pliers
flat head screw driver
new sprocket


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PUT YOUR BIKE ON SOME STANDS

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The first thing that I did was remove the sprocket cover. There are three 7mm bolts that hold the cover on. They don't need to be torqued or anything.

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If your sprocket cover is dirty, this is probably a good time to clean the inside and remove all of the extra gunk from the chain goo.

Next, you'll want to remove the cotter pin and loosen the rear axle nuts. This is the easy part of the rear axle work.

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Work the chain tension bolts and loosen the chain to get some slack. YOU"LL NEED IT.

Now go back to the sprocket and bend the lock washer FLAT. This is important or you will never get the bolt off.

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Now, you'll need the 30mm torque wrench to get this bolt off. You'll also need to put the bike in gear and have someone press the rear brake pedal. I didn't have anyone to help. So, I sat on the bike and one handed the torque wrench.

Getting the old sprocket off is quite easy. Getting the new sprocket on isn't too hard, you just need to relax and make sure you push it on the little gear teeth with care.


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Slide the new sprocket on, reinstall the lock washer and bolt and tighten. You will need to make sure to REFLATTEN the lock washer once it's all good and tight.

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Once this is all done, retighten the chain per the manual's instruction and you're pretty much set.

You just need to reinstall the sprocket cover and YOU"RE DONE. GO FOR A RIDE!!!!

Here is a final shot of the difference between the 16 T sprocket and the original 15T sprocket

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First Impressions
 

After the first ride, all I can say is "WOW".

For those of you who think that first gear is useless, you need this new front sprocket.

I wasn't able to reach a higher top speed, but it wasn't because of the lack of engine. The extra mass of the sprocket must be holding back some of the GZ's punch, because there are plenty of revs left at 70mph. There just isn't enough grunt to carry it over the 70-75 mark quickly. I reached 75-78, but it took a while. This was on a slight incline of rolling road. IF I had a downhill, I have no dobut that I would have reached 90.

OK, the good stuff.

The gears are much more useable and cruising speed is increased without the vibration or buzziness.

1st gear is now capable of reaching 25+MPH without redlining
2nd gear will carry you to 30-35+. Again, without redlinig.
3rd gear is good for 40-46
4th gear can easily reach 60mph
5th gear will go on forever

It's important to note that these numbers come without having to goose the motor at all. These are all cruising speeds.

These numbers are'nt fantastic. However, anyone who spends a lot of time on the bike knows that the stock gearing isn't capable of reaching these speeds without frying the motor. I don't even think the stock gearing can do it while frying.

The most important part of the mod comes from the fact that riding on the highway(4 land roads) around 55-65 mph is no longer buzzy or nerveous.
The engine seems very smooth with this gearing in all gears and, again, I must stress that the increased speed comes with the engine doing less work.

I think this is a must do for anyone who spends a lot of time on the time or rides on speedier highways.

TOTAL COST= $18.95

Nice job on the How To guide!

I'm not sure if it's too coherent. I get busy watching the Braves and that kept most of my attention.
:2tup:

Well done job on the "How To". Both the text and phots were very professionally done.

Cheers!

Jonathan, excellant "how to" on the sprocket change. I have wondered about an extra tooth up front. Sounds like it might be the way to go. How many miles have you ridden before the change ?? And what condition were the chain and front sprocket in ??

Good job. :tup:

I've been considering doing this myself but decided to wait until I replace the chain. You have convinced me to its a good thing to do. Thanks.

Did you wash the bike before you started? Seems awfully clean.

Nice job. I think even I can do this. By the way, where did you buy the 16T sprocket?

BadBob,
were you making fun of my pollen covered rain-spot mobile? I sure hope not. The pollen count was really high for a while and I haven't really given the bike a good washing in a while.

David C83:
I bought the sprocket from www.bikebandit.com It's a JT front sprocket. Do a search by DRIVE components and then select JT - Suzuki and you'll see the GZ250. All of the years are the same. So, if you have to choose a 2004 or something, it will work on the newer models.

Water Warrior:
I had about 1500-1600 miles on the bike before the change. It's really worth it.

I didn't have to change the chain or anything and the original sprocket wasn't worn at all. It was alittle gunky from chain goo, but it's all good now. This whole process also allowed me to readjust the cahin tension. That's always nice.

Cheers,
Jonathan

Nah! Not making fun. Mine is greasy under that sprocket cover. I did notice rusty spots on the chain but not pollen.

Sprocket
 

Hey,

I noticed that the OEM Suzuki sprocket has a sort of rubber pice to it, and looks to be a bit more heavy duty.
Any reason or function that anyone can speak of for that rubber washer part on the OEM?

As well, when you said you adjusted the chain tension, by how much?
More slack, less? how much less?

Im going to do this mod myself, but I want optimal chain tension.

Thr rubber is supposed to make things a little more silent overall. Most reports I have heard say little to none for noise abatement. I believe SunStar still supplies Zuk with their sprockets and they are good quality items. Shop online for the same at a lower price than your local dealer or support dealer til you need really need him. It's all a matter of choice.

Jordan,
I adjusted the chain tension to meet the regular specs. Check the service manual for this info. Just tighten it up to where it should be with a normal sprocket. the amount needed depends on your current chain tension.

Outstanding, excellent how to. :rawk:

Something tells me to get the Suzuki sprocket with the rubber sound deadener. I think by the looks of it it seems a bit more sturdy than the aftermarket ones, and although it may not make a major difference in sound? Im sure it makes some - in quality as well.

Dunno.

I think I can find a good salvage OEM for the same cost or less as an aftermarket.

There is no OEM Suzuki 16T sprocket that will fit our bike. The rubber sound deadener (if that's even what it is) has no fuction. What I mean by that is that there is no difference at all between the 16T JT sprocket and 15T Suzuki sprocket besided increased cruising speed and decreased RPMs.

Assuming that the quality of the aftermarket is inferior to that of the OEM sprocket is a mistake. After having this thing on for 200 miles now, I can't imagine why Suzuki wouldn't make this sprocket standard for our bikes.

The decreased revs at cruising speed make for a much more pleasant ride. There is no longer a nervous feeling above 55mph. The bike settles and it much more capable of making long distance rides.

After riding quite a bit, I've noticed an overall decrease in 0-60 times, but it's negligable. The increase in every other aspect outweighs it anyhow.

Actually,

I spoke to a dealer and the parts guy and there is a 16 tooth sprocket that will fit the bike.
It is a bit thicker/sturdier, and the rubber piece does do some dampening.

Im sure the aftermarket part works fine, but Ill stick with the OEM.

In any case, I wonder what a front AND rear sprocket change would do..

Changing both sprockets to achieve even lower RPM might be counter productive. The 250 only has so many horsepower to work with and you might actually make top gear useless. You wouldn't have the power to pull real tall gearing.

I wonder if that would be true with the big bore kit Im having put in it though ;)

Who makes a big bore kit for this bike?

Like the sound of a big bore kit. Bumping up the displacement another 100 cc's or so would be a huge difference. The added displacement even in mild tune for reliability would likely allow for another tooth on the front sprocket and a couple less on the rear. Without going overboard this combo could be very nice for cruising the highways and give a longer, more powerful pull in every gear. But here is a less than great thought. Would the 250+ develope a vibration typical of larger thumpers ??

Well,

Obviously yes I would say that the virbration will increase quite a bit. The kit adds only about 80cc's more and yes, Im sure of the increased vibration.
Still - I highly doubt it would be bad at all.

I would love to have the bike geared for 1/4 mile quickness, and easy highway revs up to 90Mph.

I'm going to be skeptical of this big bore kit until I see it done.
I don't mean any offense to you, but I've seen more than a few 250cc bike riders make claims about big bore kits that don't exist and all types of other schenanegans.

Bro, look at the link in my other posts.
i ordered the parts, and they are readily available for this engine.

16T Sprocket and Hill Climb
 

Did this mod take away too much power? Right now, I generally have to downshift from 5th to 4th to get up many hills. After the mod, does it still climb decent in 4th? It seems like there would be enough oomph in 4th to handle it, but thought I'd check before I ordered a sprocket.

Thanks for getting back on topic :2tup:

Without a problem. There isn't any power loss. The power has just been spread out over longer gears. If you get up into the top of the rev range in any gear it will still move.

I find that 4th is actually more useful. Normally, aroud the time that you would shift to 5th, say 45-50mph, you can hold out in 4th, eliminating the downshift scenario alltogether. I use the new 4th gear well into the 55mph range. It's capable of 60 without redline.

My initial reaction was a little over the top. Having spent more time on the bike, the change isn't mindblowing; it's utilitarian. I recommend this mod to anyone and I can't understand why Suzuki wouldn't use this as the standard gearing. However, if you're looking for blow-the-doors-off acceleration you're looking in the wrong place.

The 13% increase in gearing yields much more even riding, fewer gear shifts, increased fuel economy and, one would imagine, a longer engine life as a result of the decreased need for excessive revving.

Take care,
Jonathan

I think in this case clearance would be an issue. With the 16T sprocket, the chain is already pretty close to the engine block. Aside from that, I doubt that you could find a 17T sprocket.

Thanks for the info Johathan! I wasn't looking to blow away any doors, believe me. What I am looking at are some long trips this summer, possibly up to 1000 miles or so each running at 55-60mph, and didn't want to be running with high revs all day long. I'm sure the bike would take it, but I'm also pretty sure it would shorten the engine life considerably. This mod just sounded good, and I really appreciate how detailed the instructions are, too! I just ordered the sprocket, hope it shows up by this weekend. Thanks again!!

How do I lose this "Newby" tag? Heck, I've been here a long time, especially in dog years!

Im wondering if you saw that for the JIT sprockets, they sell the Universal Bushings that go with th 16 toother.
Currious to know if you checked that out.

Seems to depend on the number of posts. But I don't really know.

Hey, what can I say? I post quality, not quantity! Heh heh

Actually, doing 55mph should not shorten the life. If you go to http://home.comcast.net/~pat1776/Alaska05/index.html (copy and paste into your browser), you can read the story of a guy who did 10,000 mile Alaskan road trip on a gz250 in 19 days. He still has the bike and now has close to 50,000 miles on the bike.

Yes, I believe his name is Pat, and I've read the story and chatted with him as well. If I stick with 55, I'd be fine, and I understand that. However, there are times....

I consistantly keep my 07, at about 65Mph.
I think this was good durring the break-in perriod, but I dont sense that the engine is overworking itself.

Well, in any case, I've already ordered the sprocket, and will install it when it arrives.

Hey, I'm not "Newby" anymore!!

Gosh, I miss the good old days.... heh heh

There you go. It must have passed over around 25 posts.

As I mentioned the sprocket change is no big deal. Having the maintenance manual is always a boost to one's confidence, I'd recommend it.

Have fun and post your results here so others will have a second opinion on the sprocket change.

Take care,
Jonathan

PS: I have a couple more detailed photos if you need any help. Feel free to PM me.

Got my "go fast" (sprocket) today in the mail. It took all of 30 minutes to do this mod, start to finish. My thanks again for the step-by-step instructions - they were perfect! Only had time to make a quick run through the neighborhood, then came back to check nuts and bolts again. Will give a better description of how it runs when I can get it out on the road, however - at first blush, it's nice! It's difficult for me to describe, but all I can say is that it seems to run "smoother" - I think that's because of the lower rpm's. It does make a definate difference, at least at low, neighborhood speeds.

Thanks again for the terrific job with the instructions!! :2tup:

Just wait until you get out on a nice country road and start plowing through some rolling hills around 55-60. The smile will last for days.

The neighborhood effect is much less than the difference on the open road.

I'm glad I could help.
Jonathan

55-60?

My bike does that stock.. :cry:

How about 75-80?