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Cheap speedo healer alternative?

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Ghost
Could Be A Chat Bot



Joined: 28 Jun 2007
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PostPosted: 08:20 - 02 Apr 2012    Post subject: Cheap speedo healer alternative? Reply with quote
Just downgeared my GSXR 600 K1 with some nice shiny new Talon sprockets and a gold DID X ring chain. -1 on the front and +2 on the back. I knew it would affect the speedo slightly but this is ridiculous, following other traffic at what I assume to be 70ish it's reading 86/87 mph, and I've also had an indicated 165 on the clock but it got up there way too easily!

So it needs sorting out, but I'm loathe to spend £85 quid on the little SpeedoHealer box. Was wondering if there's any alternative companies out there doing the same thing for less? I'm not fussed about all the datalogging and 100% accuracy the speedohealer offers, I just want to get it reading something like so my mileage doesn't go up stupidly!

Any suggestions would be appreciated!
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P.
Red Rocket



Joined: 14 Feb 2008
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PostPosted: 09:28 - 02 Apr 2012    Post subject: Reply with quote
Is yours not run off the front sprocket nut? Neutral
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Ghost
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PostPosted: 15:47 - 02 Apr 2012    Post subject: Reply with quote
Yeah it is hence the Speedo over reading!
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P.
Red Rocket



Joined: 14 Feb 2008
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PostPosted: 15:52 - 02 Apr 2012    Post subject: Reply with quote
The nut doesn't change size though? Your bike looks identical to mine and the sensor looks like it reads from the sprocket nut.

Surely its not that?! Neutral
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truslack
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Joined: 08 Apr 2007
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PostPosted: 16:01 - 02 Apr 2012    Post subject: Reply with quote
##Paddy## wrote:
The nut doesn't change size though? Your bike looks identical to mine and the sensor looks like it reads from the sprocket nut.

Surely its not that?! Neutral


But the nut is spinning at a different RPM for the same back wheel speed as standard...
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P.
Red Rocket



Joined: 14 Feb 2008
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PostPosted: 16:06 - 02 Apr 2012    Post subject: Reply with quote
I'm majorly confused... its probably been a long day or some shit... but surely if the nut goes round 3 times in 1 second the computer knows thats 20mph.. or does it just spaz out.

I've not got a speedo anymore so not too bothered with my speedo readings... but I always assumed it would work itself out.

Do normal analog readings from front/rear wheel stay the same? If it was a wheel drive speedo.
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johnsmith222
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Joined: 26 Dec 2008
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PostPosted: 16:09 - 02 Apr 2012    Post subject: Reply with quote
##Paddy## wrote:
I'm majorly confused... its probably been a long day or some shit... but surely if the nut goes round 3 times in 1 second the computer knows thats 20mph.. or does it just spaz out.

I've not got a speedo anymore so not too bothered with my speedo readings... but I always assumed it would work itself out.

Do normal analog readings from front/rear wheel stay the same? If it was a wheel drive speedo.


Spinning 3 times in a second is no longer 20mph because there is a missing tooth on the front and an additional two teeth on the rear.

So for every rotation of the front sprocket, the rear wheel is actually rotating less than it did when stock.
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P.
Red Rocket



Joined: 14 Feb 2008
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PostPosted: 16:13 - 02 Apr 2012    Post subject: Reply with quote
The engine is still at the same speed though right... I'm just getting confused somewhere..
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truslack
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Joined: 08 Apr 2007
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PostPosted: 16:15 - 02 Apr 2012    Post subject: Reply with quote
But the back wheel is spinning at a different speed for a certain amount of front sprocket revolutions because of the different sized sprockets.
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P.
Red Rocket



Joined: 14 Feb 2008
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PostPosted: 16:17 - 02 Apr 2012    Post subject: Reply with quote
truslack wrote:
But the back wheel is spinning at a different speed for a certain amount of front sprocket revolutions because of the different sized sprockets.


Yea.. I'll just give up Laughing Use stock gearing, problem solved Laughing

This has made me change my mind about downgearing though...so thanks Wink
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johnsmith222
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Joined: 26 Dec 2008
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PostPosted: 16:38 - 02 Apr 2012    Post subject: Reply with quote
##Paddy## wrote:
The engine is still at the same speed though right... I'm just getting confused somewhere..


When downgearing, the engine actually has to spin faster to maintain a certain speed eg 70mph compared to stock.

EG. at 70mph stock you might be sitting at 6000rpm in 6th.

After downgearing, 70mph in 6th will now be at 7000rpm.

This is why downgearing reduces the potential top speed of a bike. redline in 6th will no longer be the stock top speed, the top speed will have reduced.

The sensor "senses" how quickly the front sprocket is rotating but cannot tell how many teeth are on it. That's why your speedo messes up when you change the number of teeth on it.

Think of it. if a front sprocket has 18 teeth then it will move along the chain 18 links per rotation.

Say, you changed the front sprocket for a 16 tooth one. The new sprocket would result in only 16 links being travelled per rotation. That means that the back wheel would not be rotating as fast in relation to front sprocket rotation when compared to stock.

The result is the overreading speedo.

If you have a huge wheel (stock front sprocket) turning 10 times in a minute, will the wheel travel the same distance as a much smaller wheel (smaller/less teeth front sprocket) turning 10 times a minute?

The frequency of rotations is irrelevant to speed when the diameter of the wheel is not known.

This is why the speedo misreads after downgearing. It "thinks" the sprocket that is on your bike is larger than it actually is. Therefore it thinks a further distance has been travelled per rotation than actually as.

BTW. Front wheel speedo drives for the win. Thumbs Up
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shadylee
Two Stroke Sniffer



Joined: 02 Nov 2011
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PostPosted: 17:03 - 02 Apr 2012    Post subject: Reply with quote
Biologic waterproof case for your smartphone £32
Cheap gps app with big numbers 99p
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Ghost
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Joined: 28 Jun 2007
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PostPosted: 18:24 - 02 Apr 2012    Post subject: Reply with quote
shadylee wrote:
Biologic waterproof case for your smartphone £32
Cheap gps app with big numbers 99p


Had thought of wiring a cheapo satnav in permanently for about five seconds, but it won't solve my issue of the bike showing significantly more miles than it's actually covered. Which will bum my resale value Sad

Maybe I just need to spunk out the 85 quid for the proper thing.
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iooi
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PostPosted: 19:01 - 02 Apr 2012    Post subject: Reply with quote
##Paddy## wrote:
I'm majorly confused...

Do normal analog readings from front/rear wheel stay the same? If it was a wheel drive speedo.


Gearing comander

Front wheel, Yes.

To help get your head round it.

If you put a lower/higher profile tyre on the front wheel.

How would that effect the speedo if driven from the front wheel.

My Versys has a sproket driven speedo. Changing the rear wheel from 60 to 70 profile corrected the in built error Thumbs Up
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DrDonnyBrago
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Joined: 03 Jan 2010
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PostPosted: 19:30 - 02 Apr 2012    Post subject: Reply with quote
##Paddy## wrote:
I'm majorly confused... its probably been a long day or some shit... but surely if the nut goes round 3 times in 1 second the computer knows thats 20mph.. or does it just spaz out.


Without wishing to teach a grandmother to suck eggs:

For simplicity sake, let's imagine a hypothetical bike where both the front and rear sprockets are exactly the same size, one turn of the front sprocket = one turn of the wheel. You can make the hypothetical wheels orange and smash some bits up if it helps Laughing .

Now, take an identical bike and down gear it so that the rear sprocket is made bigger than the front. On this bike, one turn of the front sprocket = only a 3/4 turn of the rear wheel because the rear sprocket is much bigger than the front (think of changing gears on your bicycle).

Now, if we ride both bikes so that the front sprocket is turning at exactly the same rpm (i.e. 1000rpm), both speedos are calibrated the same and are driven from the front sprocket - both bikes will read exactly the same speed on the speedo.

If we ride both bikes for the same amount of time, the first bike (1 turn of front sprocket = one turn of back wheel) will go further than the second bike which will only go 3/4 as far (1 turn of front sprocket = 0.75 turns of rear wheel). If the first bike has gone further in the same amount of time it has gone faster than the second bike. The 2nd bike's speedo is wrong because it is telling the rider it is going the same speed as the first bike when it is not.

What speedo healers do is change the number of speed sensor pulses that the speedo receives, making it calculate the correct speed. It is normally a wee electronic device that sits in line from the speed sensor and sends the correct ratio of voltage spikes. You could probably make one using a 555 timer if you were handy with electronics.

You can also get mechanical versions (usually to convert kph speedos) that use a set of gears to reduce the rate at which the speedo cable spins.
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Sako
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Joined: 19 Feb 2012
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PostPosted: 20:16 - 02 Apr 2012    Post subject: Reply with quote
i just bought the speedo healer V4 when i downgeared my GSXR, got 2nd hand from a forum, keep an eye out, they crop up now and again.
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Ghost
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PostPosted: 20:27 - 02 Apr 2012    Post subject: Reply with quote
Sako wrote:
i just bought the speedo healer V4 when i downgeared my GSXR, got 2nd hand from a forum, keep an eye out, they crop up now and again.


Feel like selling it? Wink

Also what's a good UK based GSXR forum to join? Seems to be loads out there but I don't want to join half a dozen to find out which one's the best/busiest!
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Pete.
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PostPosted: 20:33 - 02 Apr 2012    Post subject: Reply with quote
There are a couple of ways to do it.

One is to have someone meddle with the eeprom in the clocks and change the multiplier for the speedo. It's laborious and you have to dismantle the clocks and solder bits to do the reading & writing, plus find an Einstein that can decipher the magic numbers.

Another is to do some maths and figure out the pulse rate of the front sprocket per MPH then work out a trigger system for the rear wheel and run the sensor to that, so it is now unaffected by sprocket changes. It's different for every bike though because of the different gearing.
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Sako
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Joined: 19 Feb 2012
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PostPosted: 20:52 - 02 Apr 2012    Post subject: Reply with quote
Ghost wrote:
Sako wrote:
i just bought the speedo healer V4 when i downgeared my GSXR, got 2nd hand from a forum, keep an eye out, they crop up now and again.


Feel like selling it? Wink

Also what's a good UK based GSXR forum to join? Seems to be loads out there but I don't want to join half a dozen to find out which one's the best/busiest!


gixerjunkies seems to be the best bike specific forum, but obviously THIS is the best bike forum! Thumbs Up

...and no, i won't be selling mine anytime soon, only paid £40 still in the box.
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Tom85
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Joined: 25 Jul 2011
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PostPosted: 21:10 - 02 Apr 2012    Post subject: Reply with quote
I have a speedoDRD on my bike, same sort of thing as the speedo healer. I've looked on ebay and there going for about £45 but only in the states so £20 postage. Might be worth trying to find somewhere that sells them in the uk. Mine was on the bike when i bought it by the way, I've not recently lost my memory Wink
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