Brakes, fork seals, sprocket/chain, ratios, top speed, and other worldly advice

[tophyr]

Soon I'm gonna pop the wheels off my bike to replace front fork seals, brake pads all around, the tires, and the chain/sprocket. Figured I'd bounce all this off those in the know before I dive in.

• Brake pads: I'm lookin at front/rear EBC Organic Brake Pads off www.ronayers.com for $24.88 a pair. Good? Suzuki OEM ones are $28. Not planning on replacing either rotor.
• Seals: My service manual talks of an oil seal driver. Bubba_zanetti mentioned that a special tool would be required to install the seal, and that if I simply hammered the seal in there, it would soon leak again. How much do these drivers cost? It seems like a common procedure, but is it the sort of thing that a lot of people do, but few do correctly? Should I just take the forks to bubba and let him do it (keep in mind i'm a starving college kid)?
• Tires: Dunlop GT501s, 140/80 rear 110/70 front. Thoughts? I'm worried most about wet-surface performance - commuting across a lake in Seattle can be kinda scary sometimes.
• Sprockets/Chain: The sprockets and chain on the bike are at the end of their life, so I'll be replacing them regardless. However, I was wondering about tooth counts - stock I've gathered is 16/40. I was figuring on bumping the front down a tooth or the back up a couple so as to give me a bit more torque to the wheel (maybe 15/40, or 16/42). My bike already doesn't seem to have the umph to get much past 100mph (it takes me probably a good quarter to half mile to get from 90mph to 100mph on level ground). With a little lower gearing, I imagine I might actually increase my effective top speed, because it's got plenty of room left on the tach, the poor thing just can't put enough power down.

Speaking of top speed, what is the general consensus of the GS500's top speed? (I've got an '89.) I have yet to take mine beyond 100mph, because of the aforementioned clear-quarter-mile requirement to simply go from 90 to 100. Is this normal? I just recently had my carbs cleaned and synched, and the thing hauls like a raped ape all the way thru 11k rpms up till 80ish mph, and still strong to 90, but there it's like it hits a brick wall. I figured it's largely because I don't have a fairing and the engine only puts out 45hp - if I duck down low it does seem to climb more easily in the 90's. If it can't go much higher than 100mph I don't think I'll be up nights crying... one of the reasons I got this instead of a 160mph crotch rocket is because I want to live to see my 21st birthday... but still, it'd be nice to know if the bike's performing like it should.

Thoughts? (Oh, and worldly advice.. um.. ... ... well, f%$k it, I'm 20, I'm not going to take it anyway )

[sledge]

Do a search Mate, all these topics have been covered many times.

[budget speed demon]

Your understanding of gearing is all wrong.

1. Stock sprocket sizes are 16/39
2. If you go down in size on the front sprocket and or up in size on the back (ex.15/39 or 15/42) you will give yourself more low end torque and actually reduce top end power and speed. If you're looking to solve your 90-100mph try going up a size in the front and/or down in the back (ex. 17/39 or 16/37) this will reduce your low end torque but give you more in the top end.


In terms of tires, if you're going to go with a 140 rear, stick to 140/70, not the 140/80. Everyone I've talked to who put a taller tire on the back has hated it. The stock size for the rear is 130/70.

[scratch]

Why did they hate the taller profile?  Handling?

One thing to remember is that if you go to a larger diameter rear tire, it's almost the same as going 1 up on the front sprocket, or down a tooth or two, on the rear sprocket.

[makenzie71]

If you ever ridden on a tall-profile tire it really kills the "sturdy" feel.  The taller it is the more "fall-in" there is and on a rim so narrow, an 80-series tire could make handling quite fickle.

[makenzie71]

]Brake pads: I'm lookin at front/rear EBC Organic Brake Pads off www.ronayers.com for $24.88 a pair. Good? Suzuki OEM ones are $28. Not planning on replacing either rotor.[/li]

You can get EBC pads for less and have better results.

[li]Seals: My service manual talks of an oil seal driver. Bubba_zanetti mentioned that a special tool would be required to install the seal, and that if I simply hammered the seal in there, it would soon leak again. How much do these drivers cost? It seems like a common procedure, but is it the sort of thing that a lot of people do, but few do correctly? Should I just take the forks to bubba and let him do it (keep in mind i'm a starving college kid)?[/li]

Yes it does require a special tool to set the seal but you can make your own out of PVC.  While you have the forks disassembled just take and find a piece of scedule 40 PVC that fits closely and a coupler that fits it (more leverage, better grip).  You can use this as a slide hammer to set the seal.

[li]Tires: Dunlop GT501s, 140/80 rear 110/70 front. Thoughts? I'm worried most about wet-surface performance - commuting across a lake in Seattle can be kinda scary sometimes.[/li]

Go with the 70.

[li]Sprockets/Chain: The sprockets and chain on the bike are at the end of their life, so I'll be replacing them regardless. However, I was wondering about tooth counts - stock I've gathered is 16/40. I was figuring on bumping the front down a tooth or the back up a couple so as to give me a bit more torque to the wheel (maybe 15/40, or 16/42). My bike already doesn't seem to have the umph to get much past 100mph (it takes me probably a good quarter to half mile to get from 90mph to 100mph on level ground). With a little lower gearing, I imagine I might actually increase my effective top speed, because it's got plenty of room left on the tach, the poor thing just can't put enough power down.[/li]
[/list]

First, 100mph is about where you should start thinking about why you have a GS500.  It's not really meant to go that fast in uncontrolled inviroments.

Dropping the ratio will get you a little more speed...not much, but some, but so will ringing out your gears.  Shift at redline and you'll be able to get a lot highe

Theres no reason why a GS can't top 120 or so.

[Alphamazing]

Go with the 130/70 rear tire. The 140 won't do anything for you.

As for top speed, I've hit 115 indicated. You're right though, if you drop the sprocket in front it'll give you a bit more oomph, which should increase your top speed since it isn't gearing limited. It'll bring your RPMs up and hopefully give you some more power to work with. 115 though... it doesn't really need to be going that fast. I was only doing it to keep up with 4 guys on FZ1s who blew by me like I was standing still. They were in the 150s.

[tophyr]

For the record, I did search on all this stuff That's how I knew what all to put in that list.

Mackenzie, you mention that I can get EBC brakes for less and that they'll do a better job. I'm not sure you understood (or I'm just retarded and don't understand you) - EBC's what I'm planning on going with. $24 vs $28, and like you said better-than-stock performance.

Everyone seems to say go with the 70 - I don't think the GT501's come in a 140/70-17, that's why I had to order the 80. I haven't paid for the tire yet though, so if someone could point me to a 140/70 GT501 (or equivalantly priced good rain/sport tire) I'd be much obliged. Like I said, the highest priority with my tires is that they have excellent wet-condition performance. I'll go look at what's on the bike tomorrow, as I absolutely love how it handles right now.

Gearing, Mackenzie and AlphaFire nailed it. It's not that I'm looking to rampage around the highways around here at 140mph.. again, trying to live to see 21 years. I just figure a lower gearing might enable me to use the full rpm range of 5th and 6th a bit better.

[Trwhouse]

Hi there,
Here's my take, from a previous thread:
http://gstwins.com/gsboard/index.php?topic=23614.0

    Re: Just bought a GS!
« Reply #8 on: January 19, 2006, 12:35:31 PM »
   

I tried Dunlop Elites on my GS500E several years ago and was VERY unhappy because they didn't have 70 Series tires and I had to use 80 or 90 Series aspect ratios. Terrible handling, and the bike FELL into corners. Unnerving.
Then last spring I mounted a set of proper 70 Series Michelin Macadam 50/50E tires and they are GREAT!

http://two-wheels.michelin.com/2w/front/affich.jsp?codeRubrique=2092004104059&codePage=2092004104059_10092004111900&lang=EN
My bike handles great again, traction is excellent wet or dry, braking is phenomenal and my bike is much improved.  I used stock sizes and am VERY pleased.

The full tire recommendation thread from last October is at:
http://gstwins.com/gsboard/index.php?topic=22069.0

Good luck and have fun!
Yours,
Todd

[RVertigo]

I like my 15T front sprocket...

If you do a LOT of freeway, I'd just stick with the 16T...  Otherwise, go for the 15T...  And...  I'd stick to the 130/70 tire...  Sport Demons are pretty good.

[tophyr]

I looked on my bike the other day and I've actually got 130/90 on the back tire. A 140/80 will actually be 7mm shorter than my current tire, so it'll actually be more stable than what I'm used to.

[3imo]

I may be mistaken, but I was under the assumption that 5th gear will give you your top speed not 6th.

The first year I had my GS I would struggle down hill with the wind to my back in 6th gear trying to get past 85mph.

Then someone mentioned staying in 5th gear. now I can get to 100mph with minimal effort. I can hit 120mph on a downhill.
and thats with out being tuned or modded in two years.  completely stock 99' gs500

So I think its true.

Try it and tell us what you think.

[tophyr]

I noticed what you said about 5th - it seemed much stronger than 6th gear.

Checked the exact tires I've got and they're:
front: 110/80-17 IRC 310R
rear: 130/90-17 Dunlop K591

In addition, at 8k rpm:
1st gear: 35mph
2nd gear: 50mph
3rd gear: 65mph
4th gear: 80 mph
5th gear: 95 mph
I didn't get a chance to hit 8k in 6th, but based on that pattern I'd guess it'd be 110mph. 5th gear @ 5k rpm is 60mph, 6th @ 5k is 66ish, so extend that to 8k rpm and I get 105mph.

So either way, it looks like the theoretical top speed of 6th gear (at 11,000 rpm) is ~140mph. Even 5th gear at 11k should be ~130mph.. much faster than the bike can go.

[3imo]

I believe the 5th gear is designed to get a higher top speed than 6th.  6th gear seems just for cruising.

when you want that extra 5-10 mph  6th gear is just lacking the gonads for it regardless of rpms.

I know it sounds like I don't understand gearing, but I think it was designed that way.  you want 110mph stay in 5th. you shift to 6th and she will go back to 85-90. I know its a bit backwards but she seems to be designed that way.

Of couse my bike is not properly tuned so that may be an issue. I was hoping to find that others agreed or someone knew for a fact that there is some sort of overdrive designed into the tranny.

oh well...    i'll just stay in the corner all by myself then.

[tophyr]

No, I getcha. And it does make sense. I think the fact that I've got a 90 on the back instead of a 70 (making my bike 28% faster -- mph wise -- than stock at any given gear/rpm) is mostly what I'm noticing. For example, on a 130/70, at 8k rpm in 4th gear, the bike would be doing 62.5mph instead of the 80mph that mine (with the 130/90) does. (I'm assuming that my gearing is stock, I don't have any reason to think otherwise.) The geared top speed of a stock GS should then be somewhere around 110mph - 6th gear, 11k rpm, 130/70 rear tire (obviously, for those who're gonna call fuzzy math, if you went above 11,000 rpm, you'd go faster). That seems pretty perfect, power-wise, for the bike.

[RVertigo]

6th @ 5k is 66ish

Wow...  Mine is more like 5k in 6th == 55 MPH...  That's with a 15T front sprocket and a 130/70 back tire...

No wonder you're having power problems...  Get a 130/70 tire and a 15T...  You'll have no more issues.   

[melloGS]

I've gone 115, my bike will go faster than that for sure...i just backed off.
stock except for bars. i'm on my tank when i ride like that.

[tophyr]

6th @ 5k is 66ish

Wow...  Mine is more like 5k in 6th == 55 MPH...  That's with a 15T front sprocket and a 130/70 back tire...

No wonder you're having power problems...  Get a 130/70 tire and a 15T...  You'll have no more issues.   

I'm thinkin I'll go with the 140/80 GT501 (simply because it fits, I've heard great things about it, it won't be taller than what I'm used to and I've already got 'em on order), and then go with 16/44 (mayyyyybe 15/44) sprockets. That combination should put me at a final drive gearing only 9% (or 2% with the 15T) higher than stock, so instead of going 66mph in 6th @ 5k, I'd be going 56 mph, with a geared top speed of 118mph @ 11k in 6th. (Or 52.5mph @ 5k, 110mph @ 11k with the 15T.) I'd also be putting down either 17 or 25% more torque to the wheel 

[makenzie71]

holy cow...that 140/80 is gonna fall in like no one's business...

[mjm]

....2. If you go down in size on the front sprocket and or up in size on the back (ex.15/39 or 15/42) you will give yourself more low end torque and actually reduce top end power and speed. If you're looking to solve your 90-100mph try going up a size in the front and/or down in the back (ex. 17/39 or 16/37) this will reduce your low end torque but give you more in the top end.......

The above is not correct for our GS500.  Intuitively it feels ringt - and, for some more powerful bikes, it is true.  If the bike in question has excess power available atl redline in top gear it is right - that does not describe our GS.  Our bike does not have the power to pull redline in top gear - OK maybe downhill out in Colorado or Utah - not on the flat.  Lower gearing, to a point, will increase top speed. In fact, some find that their GS can go faster in 5th than 6th.  The best gearing for top speed will have the engine hit the torque peak and stop being able to accelerate at the same time - and that will be lower gearing (go up teeth on the back or down a tooth on the front sprocket.)

If the bike has a fairing and/or the engine has been breathed on the above may not apply.  Improved aerodynamics reduce the power requirement and more power does what it always does.