Right 15 tooth sprocket for the 2004 Gs500F

[jeast]

i bought mine from the dealer for $14

[Phaedrus]

What did you ask for? A 15 tooth sprocket for a 2004 GS500F?

The nearest Suzuki dealer is an hour away. 

[jeast]

correct, but my dealer is only 30min away.  they did have to order it. 

[Phaedrus]

Cool. Maybe I will just call the dealer and have them order it and hen take a spin up to pick it up. Thanks.  I refuse to pay excessive S/H on anything. I don't need it that bad.

BTW, Motorcycle Pro Shop wrote back to my email where I said "Are you insane? $9 for shipping and handling on a front sprocket for a motorcycle? I know one place where I won't be buying a sprocket from". They simple responded with: "$9 is our minimum shipping rate." 

[melloGS]

Is it hard to change the front sprocket? do you have to change the chain or the rear sprocket too?

[chris in va]

I'd like to change mine out too on the 94.  Not much happens below 4 grand, and roll on at 4-6k is dismal at best.

So on a 94, it has a 16t, correct?  And a 15 would fix that problem I take it.  Like MelloGS said, necessary to change the chain and rear sprocket?

[sledge]

16 is regarded as the mimum number of teeth required for any chain sprocket of a given pitch, not just motorcycle final drives. Lower than 16 teeth and the chain begins to suffer from whats termed Chordal Action.  Its a nasty and unwated side effect of all hig speed chain drives and it cannot be easily engineered out. In simple terms the chain struggles to engage on the teeth smoothly due to the extra and unwanted forces generated when being driven by a small diameter sprocket. The upshot of this is a fluctuation in chain speed (termed snatch) and a dramatic increase in noise, vibration and harshness (termed NV+H) caused by the difficulty the chain has engaging. In effect the rollers slam into position between the teeth rather than being smoothly drawn into them. Increased NVH will reduce the lifespan of the chain and sprockets and will probably impact on other parts of the drivetrain, particularly if the chain is already part worn. My guess would be the splines on the gearbox output shaft would be first to suffer as that is where all the torque and power is concentrated.
Click on this link.

http://chain-guide.com/basics/2-2-1-chordal-action.html

Ignore all the tech-talk and maths and look at the graph at the bottom

It plots tooth number against unwanted speed variation and from it you can see that at about 15-16t the line
shoots up indicating that chordal action is begining to take affect. The question now is will 15t be ok? my answer is yes but you will begin to notice an increase in noise and vibration, the chain may snatch, particularly on the overun or when coasting downhill and you can expect a reduced lifespan of the chain and sprockets as a result. I certainly wouldnt go below 15t and suspect the unwanted effects of Chordal action are the reason that the Suzuki Engineers chose a 16t sprocket as standard.
In terms of reliability I think a better option would be to alter the number of teeth on the rear sprocket to alter the overall ratio. Chordal Action will have no effect on a sprocket of that size and you will not be making any scarifices to the overall reliabilty of the chain and sprockets. The question now is are they available? and I cant answer it, but I can say having one made would not be difficult for a good engineering  or specialist gear-cutting company. Take the old one as a sample and ask them to make another of the same pitch and fixing centers and however many or less teeth you want.

[RedShift]

There have been a lot of people here who run a 15T Front, and I've never heard of anyone complain of excessive chain or sprocket wear.  There have even been a few who installed a 14T, again without any word of increased failure rates.

I don't argue that "Chordal Action" is greater with reduced fron sprocket radius, but anecdotal evidence appears to support that that the effects are not significant at the 15T level.

As for why Suzuki engineers have chosen a 16T front, I suspect it has more to do with providing a balance between spirit and calm for a 40 HP bike that's aimed at the beginner and commuter.   

[gsJack]

OEM Gearing:

91-98 CBR600F2/F3   15-43
95-04 ZX6R    15-40
94-04 YZF600R   15-47
88-95 GSX1100F  15-52
89-97 GSX600F   14-46

gsJack is the gonefather of GS500's

[sledge]

redshift?
I doubt anyone would physicaly notice the increase in vibration given the constantly varying and far from ideal conditions the chain operates in, nor the increased wear rate as chains and sprockets are wearing components, But the fact of the matter still stays. A reduction in size increases vibration and vibration has negative effects.

jack?
What can I say? Obviously Chordal action and its effects wasnt a big issue to the designers of the GSX6.

[Phaedrus]

i bought the one from sprocket specialists, and it's the wrong one, you need the one with the shoulder!!!! not from them!!!

Ok, I finally got my 15T sprocket from the dealer. After dealing with their saga (they ordered the wrong one the first time, adn I suspect this time too?). Here is what they gave me, which according to them, fits the 2004 Suzuki GS500F:

The sprocket:


The label:


As you can see from the picture, there is no shoulder. I mentioned this to the parts guy at the dealer and he said it did not matter if it was there or not. Since this one does not have the shoulder, I might need to re-use the rubber grommet from the stock one, and this one might be a bit noisier than stock.

So, is he full of  or no? I won't be able to work on this for another week or two prolly, as my bike is stored out of town but I'll be getting it out when I have the time and a day off

Is this going to work, or should I take it right back and not even waste my time? (Keep in mind, this is the second one..I have little confidence in their competence).

[scratch]

You may need to use a washer to fill in the space.  I have done so with mine, and just last weekend I cleaned out the c/s cavity and inspected the splines and they are fine (16tooth, 15,000 miles).

The dealer obviously cannot distinct between models.

[Cal Amari]

According to Kerry's webpage here:

http://www.bbburma.net/Documents/GS500_Chains&Sprockets.txt

that is the correct 15T Sunstar sprocket for '94-'04 models, which I'm sure will fit the subsequent '05-'06 models as well. Though I can't eyeball anything for you (my GS went on vacation without me!), odds are good you've got the right one now.

FWIW, Sunstar sprockets are probably at least equal to the stock OEM Suzuki sprockets in quality (which is very good); in fact, I think Sunstar actually supplies most or all of the OEM sprockets for Suzuki, and probably all of the other Japanese makers.

Bottom line is, I think you've got a keeper... though scratch might be correct, you MIGHT need to shim it with a large washer. You'll need to check chain alignment after you install the sprocket to be sure, but I don't think that will be necessary. Let us know...

[Phaedrus]

Thanks guys. Like I said, I don't have my bike handy so I can't just run outside and check it out or "give it a shot" yet, and if this wasn't the right one, I would want to go back and get the one that I *should* have before I start tearing things apart.

I'll definitely keep you posted 

[scratch]

Another reason to keep your old used ones available, so you can check 'em against the new one's you order.

[flyingbeagle71]

The sprocket:


As you can see from the picture, there is no shoulder. I mentioned this to the parts guy at the dealer and he said it did not matter if it was there or not. Since this one does not have the shoulder, I might need to re-use the rubber grommet from the stock one, and this one might be a bit noisier than stock.

Phaedrus, from this picture, it does have a shoulder.  Just a really big shoulder.  The older sprockets are much thinner, see the following:



The newer bikes have a shoulder on the sprocket for spacing on the shaft    Anyway, they look more like this:



Notice the thickness.  I'm not an expert but did sleep at a Holiday Inn Express last night, so please take this info at face value... 


Edit: Changed to correct sprocket diagrams.

[scratch]

Good eye!

[Phaedrus]

Hm...yes, good eye  I understand what you are saying now. The reason I didn't think it had the shoulder is because the Suzuki OEM one they originally ordered me had a "different" shoulder. It was smaller, more like a ridge, around the inner circle. It was about as thick as the ridge of a quarter, and the same diameter of that inner circle. I noticed this one did not have it, so I assumed it was a "shoulderless" one. But it does have it, just slightly different configuration.

I see what you are saying. Thank you! 

[denman]

ok i got my 15t from a non dealer shop.   it is a sun star by sunex pn#33315  for a 2000 mod.  it was 12.00$  it fit just like stock.  see ya.

[Alphamazing]

How'd it go, Phae? Work?