So I figured why not. For $12 on Amazon, I purchased a JT 18T sprocket for my bike. After about 100 miles today I decided I would give a decent little write up since there hasn't been much, and any other relative posts are at least 2 years old. This is done on a 1990 GS.

Goals for this morning were:

1. Mount new 18T sprocket
2. Clean & lube chain
3. Clean out side cover (it was yucky)
4. Re-adjust clutch

So the swap of the sprocket was easy. Pop off old 16T, shove wheel forward (a lot), and then tighten it all up again. Yes, the sprocket clears the shift rod. It is deceptive though, looks REALLY close, but there is almost 6mm (1/4") between them. This is the one I ordered:

http://www.amazon.com/gp/product/B0068OCV0E/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

or if the link goes bad: JT Sprocket JTF565.18

This is the sprocket you need up to a 1994 I believe. Be safe, and check what you have first, there are a few different ones. Mine has no hub, it's flat, that is important. Others have a step, or hub, and that is required. Find out what is on yours first. If you need the stepped hub version:

http://www.jcwhitney.com/1990-2002-suzuki-motorcycle-gs500/motorcycle-sprocket/p3067786d58770y1990-2002j1.jcwx

I figured from what I had read thus far, that I could expect take offs to be a bit slower, but my gears would be longer, and my RPM's lower. This was my whole reason, I want better mileage. Once out of the driveway I noticed 2 things immediately. First, the bike took off! I was expecting to slip the clutch a bit, or have to roll into a fast take off. Little did I know the old girl just wanted to run! This may be due to a freshly adjusted clutch, I'm sure it is, but it didn't act at all like the 2nd gear take off I expected. The next thing I realized very quickly, was the apparent "extra gear" I had gained. Figuratively. On the 16T I would cruise through town 35mph, around 3500-4K, in 4th, now I was in 3rd. Wind it up, I'm cruising in 5th at 60, running about 4K, not 6th like I used to. Now keep in mind, this is a 23 year old bike. After a few miles, I started to test it out a little harder. I did rolling high speed take offs. Cruise 40-45, punch it to 75. This also seemed to do the exact opposite of expected. I figured rolling along at 3500 I would have to shift to really take off, but nope. While it's not in it's proper powerband, she pulled real hard! My digital speedo was skipping large chunks of numbers until i realized I was running almost 80, in 5th.
A few other bonuses, I'm not shifting mid intersection, the buzzy higher RPMs are all but gone, and the general pull from shift to shift seems a lot smoother. I honestly, in my lone opinion, think this is how the GS should have been geared from the start. I do think the clutch adjustment matters heavily here though, if adjusted well, and tight, there is no slipping and everything is very smooth. I highly recommend people do this. Is there a loss of some take-off speed? Maybe, but I did not notice it...hell, I can still beat cars.

The testing info:

All information is based on US MPG
All speeds were taken from my digital speed & with GPS
All RPM's are based on watching digital tach throughout the riding, so it's close

1990 GS500 E
K&N Drop in
Stock Exhaust
200lb Rider

16T Sprocket:



Gearing speeds @ 6000 RPM (provided by GSwiki)
1st= ~26mph
2nd= ~38mph
3rd= ~47mph
4th= ~59mph
5th= ~69mph
6th= ~78mph

Tank 1: 47mpg - Mixed Riding - Avg Speed: 55mph - Avg. RPM: 5500
Tank 2: 49mpg - Mixed Riding - Avg Speed: 55mph - Avg. RPM: 5500
Tank 3: 41mpg - 1/2 Mixed - 1/2 Highway Riding - Avg. Speed: 70mph - Avg. RPM: 6500

18T Sprcket:

Tank 1: 53mpg - 2/3 Highway Riding - Avg Speed: 75mph - Avg. RPM - 5000
Tank 2: 57mpg - Mixed Riding - Avg Speed: 60mph - Avg RPM: 4000
Tank 3: 51mpg - AGGRESSIVE Riding/ Highway - Avg Speed: 70mph - Avg RPM: 5500

Final Review Data:

Avg MPG 16T: 45.6 MPG
Avg MPG 18T: 53.6 MPG

Adjusted speeds 18T @ 6000RPM:

1st: ~34
2nd: ~45
3rd: ~ 56
4th: ~67
5th: ~76
6th: ~85


This is a definitive increase in mileage over stock gearing to me. I tried to cover the entire range of riding styles from conservative to aggressive. Does this mean I am saving a lot of money...no, it means something far more important to me...RANGE. It means I get 30 more miles per tank than I did before. That's an extra trip to work, and extra 30 to cruise the back roads and get lost, less worry about where the next fill up is. In general, the RPM range for cruising was lower, but more noticeable was the much longer gears...longer between shifts. This is nice for cruising, and I always hated shifting mid-intersection. In the end it's preference, and you can decide based on the numbers, but I will be keeping the bike geared this way until it dies!

Now for the hiccup. I removed the side cover for the clutch cable, and when I went to clean it...wow. Apparently, at some point it went WAY, WAY out of spec, and the chain had actually eaten part of the arm that the clutch cable pulls on. To the point where it was so thin I could bend it with my finger. Thats 2 creepy incidents in the last month...damn thing. Anyway, i had a spare cover with all the guts so I just swapped them. I am not sure when this happened, since I never felt, or heard anything. So it's a fair warning, make sure your clutch is properly adjusted...that arm is VERY close to the chain when it's all put together.

  .. Good info!

... Edit ... So still stock rear and no chain change?

Still stock rear, and no chain change. Rear wheel is still well within the adjustment range, so that's not an issue, just moved forward almost 3 notches.

Quote from: Soloratov on June 01, 2013, 06:53:05 PM
Now for the hiccup. I removed the side cover for the clutch cable, and when I went to clean it...wow. Apparently, at some point it went WAY, WAY out of spec, and the chain had actually eaten part of the arm that the clutch cable pulls on. To the point where it was so thin I could bend it with my finger. Thats 2 creepy incidents in the last month...damn thing. Anyway, i had a spare cover with all the guts so I just swapped them. I am not sure when this happened, since I never felt, or heard anything. So it's a fair warning, make sure your clutch is properly adjusted...that arm is VERY close to the chain when it's all put together.

This clutch cam and push rod design may have been the stupidest ever in the freaking history of suzuki and in deed the world.

You have a chain jump or break or something and you're left with a clutch that wont work os you ate the cam or broke the rod. Yeaaaaay more parts you gotta buy. Garbage design.
Of course the clutch being on the right side they could just have slapped that arm and pinion style on it they put on every other bike. Idiots. Unneccesarily complicating things.

Cool.
Buddha.

"This was my whole reason, I want better mileage."

So....what was your mileage before the gear change..and what is is after?

Cookie

well...it's only been 1 day...so, I have no idea what my mileage is yet. I want at least 3 tanks to get a decent average mileage, but for now:

16T = Avg. 46-52 mpg.

Soloratov,

What year is your bike?  The wiki lists the JTF565 for years up to 1993 but 1994 and up it lists the JTF516 which isn't available in a 17 or 18 tooth (according to the JT website).

Does anyone know if the difference is just the flange and if it matters that much?

"This clutch cam and push rod design may have been the stupidest ever in the freaking history of suzuki and in deed the world."

Did moving the rear wheel forward raise your rear end at all? That would be another plus in my book.

I modified my post.

Bike is a 1990. The sprocket is the flat design, look at what you are taking off to be sure which you need.This is a very important thing to check, the wrong one, and it will be loose, or not fit at all.

As far as the rear end, I didn't notice. The whole wheel only moved 2 notches, so, 1/2" maybe. Not really enough to change anything, especially once you sit on it. By moving the wheel forward, if anything, it would lower the bike a little.

So...........


With my standard sprocket...I get 60 to 65 MPG.........Occasional up to 70...........

I can't see the gearing mattering a bit...unless you make really long drives at sustained high speeds...like 75 mph or so.........

I spend a fair amount of time in 5th gear....sixth for sustained higher speeds.....only when I get to 80 MPH would I think of needing a higher gear.........and I don't really ride more than a minute or so at that speed......

But if fuel mileage is your goal...then riding fast is the best way to ruin that goal.........

Well let us know how it works out........

Cookie

Quote from: Soloratov on June 03, 2013, 08:48:54 AM
well...it's only been 1 day...so, I have no idea what my mileage is yet. I want at least 3 tanks to get a decent average mileage, but for now:

16T = Avg. 46-52 mpg.

I ride 75 miles a day to and from work, all expressway, so sustained higher speeds are not really negotiable.

How would gearing NOT matter? I effectively cut my rpm's in half....

One thing I noticed reading endless posts about fuel economy, no one, anywhere seems to really get the same thing. This bike seems to have it's own specific standards for every rider. Rider weight, temp, elevation, stock vs upgraded, all kinds of things. I look on Fuelly and the numbers are all over. I'm trying to provide the information based on the change, and the change alone, not the specific numbers.

while i do think gearing plays a part ... and i intend to do this 18T thing also!! ... mainly to 'move' my freeway cruising rpm lower..
with any gearing its ALL about how you use the gears and throttle .. and how that will affect fuel consumption ..

one of my fav vids to show the eco-warriors  ... mainly the second half .. but its all interesting 

That's a great episode!

I agree with the "what you do with it" statement. It's tough for me. I'm a relatively easy going kind of rider, but there are plenty of times I like to get on it and wind it up. Tough to go a whole tank conservatively for me A lot of Jeremy running through my yank veins. I think for me, the greatest advantage to the 18 is the longer gears...especially 1st and second.

finding an 18t with the flange for my k6 is proving a bit of a challenge... JT or otherwise .. 

I'm wondering if you could get the non flanged version, and just add a spacer/washer of some kind. Flange just takes up space, so I don't see why not. If you weren't on the other side of the world I would offer to make you a spacer.

thanks for the offer 

from what i understand though .. the flange is not just there to make it wider... its to provide extra surface area on the splines and therefore limit 'wiggle' ... a spacer would be a good solution .. if it were also the 13spline toothed and bonded to the sprocket .. sigh


edit ... mmmhhhrrrrrmmmm .. however... stock 16/39 gives you 2.43 .... your 18/39 gives you 2.16 ratio... nothing (i have any more patience to look for) on the JT site goes plus front/minus rear ... enough .. to give that ratio....


however ... at risk of seeming to have more money than sense... Chain Gang Sprockets offer the following (down near bottom of page) a 17/38 setup .. which gives 2.23 .. still a bit high for the purposes of keeping to the 18/39 theory

but... after a phone call... he can indeed do a 17/37 set .. which gives a 2.17ratio .. close enough for me!..

he also reccomends using a DID ZVM chain ... with the CG sprockets... and claims with good chain maintenance the combo will give up to 3 times the life of 'normal oem' gear .. he sounds like a reasonable sort of chap...

just dont ask me the cost overall.... its ummm.... welll .. i might just order the chain from o/s i think... try and minimise that part of the cost....  still... if it gives me 3 times the life? ...

and Chain Gang are Aussie Made!! .. fair dinkum! 
http://www.chaingangchainsandsprockets.com.au/suzuki-specs/up-to-500cc.html

I find this a very interesting experiment, do keep us informed. I am currently running a 15 and it really gets very buzzy at 60 not to mention 70 or 80!

Quote from: Soloratov on June 03, 2013, 08:47:59 PM
I'm wondering if you could get the non flanged version, and just add a spacer/washer of some kind. Flange just takes up space, so I don't see why not. If you weren't on the other side of the world I would offer to make you a spacer.

I used 3 Sprocket Specialist replacement sprockets on my 97 GS that did not have the hub over a period of approx 40k miles.  I questioned SS about it and they said the front sprocket would be located by the chain and rear sprocket and would run OK without spacers or hub.  This turned out to be true and every time I opened the sprocket cover the front sprocket was located right next to the retaining clip in perfect alignment.

I put same type SS sprocket on my 02 GS with the first chain replacement and ran it all winter with the rear wheel a bit out of alignment and when I checked the front sprocket in the spring it wobbled a bit on the shaft.  Turned out the sprocket spline bore was worn excessively but the shaft was OK and I went back to sprockets with the hubs after that.  So the hubless sprockets will work but the ones with the hub are better, must be the reason why Suzuki made the design change to add the hub back around 1993.

http://www.gs500.net/gallery/data/500/GSbrakeschains.jpg