Quote from: dracflamloc on July 06, 2006, 09:04:29 AMwhat tools are needed to do this mod and adjust the chain?

This is all you need for the front sprocket:



I didn't have the snap ring pliers the first time I replaced my sprocket.  Unfortunately, I can't remember what I DID use.

To adjust the chain you need something like pliers to remove the cotter pin, a 21mm (or 22mm?) socket or wrench to loosen the axle nut, and a 12mm wrench to turn the adjusters on the back of the swingarm.  Oh, and a new cotter pin or hitch pin for when you put it back together.  Ideally you would also use a torque wrench for the axle nut, but you could maybe get around that by counting / measuring the visible threads before removing the nut.

Quote from: dracflamloc on July 06, 2006, 09:04:29 AMIs there a how-to anywhere?

I know that there are multiple posts that describe the process.  Check the FAQ area first, then try a search.

Quote from: dracflamloc on July 06, 2006, 09:04:29 AMAlso, should I get another chain? What kind/where should I get it?

You don't need to get a new chain just because you change to a smaller front sprocket.  Unless the chain has already "stretched" and you can't move the rear wheel back far enough to get the correct tension.  (How many miles on your current chain?)

If you DO need a new chain, check the top section of the same "Chains & Sprockets" page I linked to earlier.  I'm sure there are many sources besides those, but that should get you started.

Thanks for the help. I've found some good threads on the topic with a few pics but no how-to kind of deal.

I'm not sure how old the chain is. I just bought the bike about 1.5 mo's ago. It looks like its in good condition. No rust or anything. Nice and sorta-shiny 

Quote from: Kerry on July 06, 2006, 09:18:56 AM
I didn't have the snap ring pliers the first time I replaced my sprocket.  Unfortunately, I can't remember what I DID use.

I just used needle nose pliers. They worked well enough.

Quote from: Kerry on July 06, 2006, 09:18:56 AM
To adjust the chain you need something like pliers to remove the cotter pin, a 21mm (or 22mm?) socket or wrench to loosen the axle nut, and a 12mm wrench to turn the adjusters on the back of the swingarm.  Oh, and a new cotter pin or hitch pin for when you put it back together.  Ideally you would also use a torque wrench for the axle nut, but you could maybe get around that by counting / measuring the visible threads before removing the nut.

22mm for the nut and 17mm for the bolt. I usually need both because the axle just spins.

Quote from: Kerry on July 06, 2006, 09:18:56 AM
You don't need to get a new chain just because you change to a smaller front sprocket.  Unless the chain has already "stretched" and you can't move the rear wheel back far enough to get the correct tension.  (How many miles on your current chain?)

I only needed a new chain because of the drastic change in teeth on the front. My chain has about 13,500 miles on it right now and still has the correct tension, but it's at the end of its adjusters. Just depends on the chain. Also, eBay has some okay deals on chains, so check there too.

Quote from: dracflamloc on July 06, 2006, 09:59:02 AM
Thanks for the help. I've found some good threads on the topic with a few pics but no how-to kind of deal.

I'm not sure how old the chain is. I just bought the bike about 1.5 mo's ago. It looks like its in good condition. No rust or anything. Nice and sorta-shiny 

Check out a topic called "The Right 15 tooth Front Sprocket for the GS500F" or something similar. Phaedrus did a write up how-to in there with pictures and everything.

sounds like a very cool mod. and yes, I know you didn't "technically" increase the power... I just couldnt think of the proper way to word it. powerband sounds better 

so you can (probably) hit 120 on the speedo with this mod , but does the shifting feel much different? I'm under the impresstion that you've brought an already close gearing much closer.





...I suppose I should just shut up and do it already.

i cant stand that high of a rpm, i want my engine to last.

o, i looked at the page, no 18 or 19 front ?

19T front: 0-60 in 'theory'

Quote from: l3uddha on July 06, 2006, 01:35:05 PM
sounds like a very cool mod. and yes, I know you didn't "technically" increase the power... I just couldnt think of the proper way to word it. powerband sounds better 

so you can (probably) hit 120 on the speedo with this mod , but does the shifting feel much different? I'm under the impresstion that you've brought an already close gearing much closer.

Shifting feels the same, you just have to do it a little bit more often, unless you short shift and don't mind accelerating at a non break neck pace. The gearing is closer, but not crazy close.

Quote from: rangerbrown on July 06, 2006, 03:30:27 PM
i cant stand that high of a rpm, i want my engine to last.

Eh, the GS engine is pretty bomb proof. Just keep it topped off with oil and do proper maintenance on it on time and it will last forever.

Did you notice any extra vibration?  I put in a 15t the other day and noticed a very slight increase in vibration of the pegs.  With good boots it's hardly noticible, but with my 'tester sneakers' I could tell it's there (still not bad though).  This isn't something that's talked about often, but I'm under the impression a smaller sprocket would mean more vibration.

Quote from: LimaXray on July 06, 2006, 11:07:08 PM
Did you notice any extra vibration?  I put in a 15t the other day and noticed a very slight increase in vibration of the pegs.  With good boots it's hardly noticible, but with my 'tester sneakers' I could tell it's there (still not bad though).  This isn't something that's talked about often, but I'm under the impression a smaller sprocket would mean more vibration.

I got vibration through the bars holding the RPMs at 8.5k to 9k. Since my pegs aren't rubber coated or rubber mounted they tend to vibrate more than the stockers, but it isn't super duper noticeable like the bars were. They vibrated a bit with the stock front sprocket, but I only noticed it on longer rides.

anyone make the 18 or 19 front sprocket?

I put in a 15T a couple weeks ago, and I think it's perfect. I can accelerate "fast enough" on the freeway in 6th. Only if I'm in a real big hurry do I downshift. I wouldn't go with a 14T because of al the freeway travel I do, and I just don't want my RPMs that high. Dropping 1 tooth I think is a bit more balanced amogn the advantages/disadvantages among gearing changes. I'll buy a bigger bike before doing any more performance work on my GS. I'm happy with it as is. Also - I've had it up to an indicated 125 mph (15T front sprocket, slightly larger front tire - can't remember the first number so {stock}/80/17) at about 10.5k RPMs. Didn't go any higher cuz I didn't want to journey into the valve float territory. Plus it was like 105 degrees out and I was on a desert freeway. Overheating would be bad.

i think im goin to do the 14 teeth convorsion... seems to be fun to ride after

I ordered a 14t. If its too crazy for me and won't allow the highway speeds I want then I'll just sell it here I guess.

You would be right to notice an increase in vibration with a smaller front sprocket. Its due to whats known as chordal action. Its an unwanted side effect of roller chain drives that Engineers have been trying to overcome for centuries. 15 teeth on a high reving sprocket should be regarded as the absolute minimum, anything lower and the sprocket will still work but it starts to seriously loose efficiency and become harsh in operation. This applies to roller chain drives in all machinery and not just bikes. Basically, roller chain cannot engage smoothly on small diameter sprockets as it is drawn on. It causes variations in chain speed which leads to a `pulsing` effect as it rotates between the sprockets. In addition to the vibration it induces elsewhere in the bike it will also reduce the lifespan of the chain and sprockets.
http://chain-guide.com/basics/2-2-1-chordal-action.html
Look at the graph in the link, it plots no of teeth against speed variation as a percentage. The line starts to shoot up at about 15 teeth, well thats chordal action kicking in.

Hello everyone. 

I think this might be the first mod I perform on my 98 gs500.  I love the gs but when I am under 4000 rpms it just feels like it has no power.  I feel like this mod would put my rpms a bit higher and make my power much more useable. 

Here is a question to anyone with this mod.  Have you also replaced your rear sprocket or only the front sprocket?  I am seriously considering this mod so let me know if you have also swapped the rear sprocket.  I have a limited amount of knowledge about the gs but hopefully I can do this mod on my own.

I get around 50 mpg but that is probably because I have to dog on the engine a lot fo get up in speed.  I think with the type of riding I do this mod might increase my gas mileage.  I ride mostly in the city and sometimes on the freeway so I am constantly shifting gears.  I dont know if my reasoning is logical though.  I dont think my bike needs a new chain but I guess I will find out when I try to install the sprocket.  I was also considering a timing advance kit but I have not been able to locate one.  The gs is my first bike so I dont want to modify it too much, but I feel like these two mods are necessary for my kind of riding.  When I am cruising in the city at low rpms I just feel like the gs is slugish.  My belief is that this modification will make the bike a little more peppy for city driving so I wont have to rev the engine so high.

Any comments on this would be greatly appreciated.  My friend used to work at an atv shop so he can probably help me install it.  thanks for your help everyone.

You don't need to change the rear sprocket, only the front.  Changing the front sprocket takes less than 10 minutes, maybe 20 tops if it's your first time using a wrench.  It is also easily reversable.  Being a new rider, I would get a 15t sprocket, it's a little more forgiving than a 14t would be. 

As for revving the GS, you have to rev it.  It's a motorcycle, not a car.  There is NO power under 4000 RPM, you should be cruising at LEAST at 4k.  I personally cruise between 5k and 6k.  Riding around on the GS under 4k is like riding around in a car under 1k, it has no power and will only lug.  So don't be afraid to rev it, that is what it was designed to do! 

edit: also, lowering the number of teeth on the front sprocket shoud give you WORSE gas mileage, but not too much worse

I agree with everything LimaXray said.

The first two things I said at the top of my first post was that THIS MOD IS NOT FOR BEGINNERS. I stand by that. On a stock bike you shouldn't be anywhere near 4000RPM unless you're going from a stop or coming from a stop. All other times you should be above 5k RPM if not higher. Try that for a while, then come back to us on this.

I shift at 6 and 7k a lot but when I try to save gas I shift it at 4k.  Maybe I am just wasting gas doing this.  I might just start with a 15t sprocket but by the description everyone has given I think 14t would be an okay swap.

When do you consider someone ready for this mod?  Its not like I will be beating on the throttle every chance I can get just because the gears are changed.  I just think it would make the bike a lot more peppy and fun to ride.

Quote from: okayf00l on July 11, 2006, 02:37:40 PM
I shift at 6 and 7k a lot but when I try to save gas I shift it at 4k.  Maybe I am just wasting gas doing this.  I might just start with a 15t sprocket but by the description everyone has given I think 14t would be an okay swap.

When do you consider someone ready for this mod?  Its not like I will be beating on the throttle every chance I can get just because the gears are changed.  I just think it would make the bike a lot more peppy and fun to ride.

I had about 8000 miles under my belt before I did this; main thing is to make sure you're comfortable riding in high RPMs. I was regularly shifting around 10k and 11k, and still do with this new sprocket. I was wailing on this thing with stock gearing, and still do it with the 14T.

Consider this... the power STARTS at 7k RPM.

Try running higher in the RPM range with stock gearing before you try this, I think.

Also, shifting around 4krpm - Since the engine has no power down there you are putting a lot of load on the engine, and thus wasting gas.