Down gearing

[curryfishball]

Hi

I want to down gear my Gixxer 600 by upping the rear sprocket by 2. Is there any way to recalibrate the speedo so that its correct after the change? Its a K5 model if that helps.

Thanks
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The world is a book, and those who do not travel, read only a page.

[the grim reaper]

I just do a mental change on mine, I have one tooth less on the front and I have used a GPS to check my speed, it's 10% over reading, so I know that 55mph is a true 50mph.

Other than that, it could be done with some clever electronics but you;d have to capture the existing signal at 10mph intervals and work out how to adjust it.

My bike now wheelies nicely in 2nd off the throttle though, as I found out this morning

Cheers

Grim
____________________
Adverts don't always work: Remember that advert, where the army are running across the desert and they have a wounded man on a stretcher. They get to a ravine, the bridge is down and a caption pops up that says, 'What are you thinking?'. I don't know about you but I was thinking, 'Christ, I'm glad I'm not in the f***ing army'.

[curryfishball]

Thanks, I was hoping I could adust it, would be nice to see the actual speed rather than working it out.

Do you know what the difference is for chain size? My bike uses 525 as standard, however when I was on the Renthal site, it says there is a 520 conversion kit for mu bike. Is it the width of the chain or something?

Thanks
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The world is a book, and those who do not travel, read only a page.

[G]

You can get a box to adjust your speedo, but as mentioned you may make it 'righter' anyway, depending on how it is out.

520 width chain is narrower than strandard and will give you slightly better acceleration/pickup for a possible slightly reduced chain life.

You would need to replace both sprockets and chain at once to convert to 520.

[curryfishball]

Thanks, I'll give that a try and see how it goes. Should be fun with faster acceleration from down gearing it!
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The world is a book, and those who do not travel, read only a page.

[Odie]

where is your speedo drive taken from?
The front wheel or the rear wheel?
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[Bendy]

You wants one of these

https://www.speedohealer.com/images/sh_1_sm.gif

https://www.speedohealer.com/

[curryfishball]

Thanks, that looks really good, costs quite a bit though! But at least I'll get an accurate reading and not have a super high mileage bike.
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The world is a book, and those who do not travel, read only a page.

[curryfishball]

Oops, read the price wrong, I guess its not too bad
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The world is a book, and those who do not travel, read only a page.

[brooky]

I was always under the impression newer bikes took the speedo reading from some sort of pulses within the engine, Guess I'm way out.
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Suzuki GSX-R 750 K6.

[Odie]

I was thinking they took their reading from the front end.
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[Kram]

you could get a bicycle speedo, and attach the magnet on the front wheel (brake?) somewhere and use that? would give an accurate reading
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FS1E -> SR125 -> CB400N -> CB650 -> FZR600 Genises -> VFR400 NC21 -> CBR900RR Fireblade -> Renault Clio 1.4

[Odie]

Your speedo works off the front wheel, that means that your speedo is set to that wheel size.
How would altering the gearing on the rear wheel affect a speedo that works off the front wheel?
Please some-one tell me, am i missing the point?
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[Bendy]

Lots of bikes don't work off the front wheel, they work off the engine or the front sprocket. So if you change the gearing, you change the ratio and the speedo will be wrong.

There's no chance a 2005 gsxr has a speedo driven off the front wheel.

[fast_tzr]

But surely if you don't change the front sprocket the speedo reading will still be the same?

[curryfishball]

if you increase the rear sprocket, the front will need to rotate more in order for the rear to travel the same distance. so you will get in increase in mileage, and also an increase in mph (but you are not actually travelling any faster)
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The world is a book, and those who do not travel, read only a page.

[Odie]

No it wont affect the front sprocket if you change just the rear one the rear one.
Think about it, if the front sprocket stays the same size how will it affect the rear wheel and sprocket?
The rear wheel might be going faster if you put a bigger rear sprocket on but it will not change the front.
____________________
You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[G]

[curryfishball]

if you have a push bike you can try if out yourself. keep the front sprocket constant, and measure how many cycles it takes you to move 20m, then increase/decrease the rear and repeat
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The world is a book, and those who do not travel, read only a page.

[Odie]

[/quote]To turn the rear wheel one revolution, the front sprocket will now need to turn slightly more/less, thus it will effect the speedo.[/quote]
But its the front sprocket that is the drive not the rear wheel!
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[brooky]

LOl, Yes the reading does come from the front sprocket , but that would only be correct if the rear sprocket was OEM.

Becuase the rear sprocket is up by two, the reading will be out becuase in the time it takes the rear wheel to spin once the front sprocket would probably spin a couple times more than what it would of originally, Hence tricking the bike into thinking its going faster than it really is.

HTH

J
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Suzuki GSX-R 750 K6.

[Odie]

There are a couple of things that are not being taken into consideration:
1) the gear box: This is pre set.
2) The front sprocket: This can be changed, bigger = slower acceleration better top end ( ), smaller = faster acceleration slower top speed ( ). This is the drive sprocket
3) Rear sprocket: This can be changed, bigger = faster accelleration slower top speed, smaller = slower acceleration faster top speed.
You could change the tyres, that would also affect the gearing and top speed but not as noticable as changing the sprockets!
But my point is that the engine is the drive not the rear wheel so its the drive you should be looking at not the "final drive" for your speedo reading.
You will only get out what you put in.
Its the front sprocket that is driving the rear wheel not the other way round!
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[brooky]

[Odie]

I know what you mean, my head hurts!
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You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[DUCMANs]