Speedo accuracy

[Dell Boy]

Hi Guys, recently discovered my speedo is reading upto 9 mph slower when travelling at 70 mph, is there a fix for this without braking the bank. Have looked at fitting a GPS speedo but have sat nav and camera already on handle bars so I am running out of space. Any ideas please.

[Hooli]

That's unusual, they normally over read by 8% ish on average. It's not got a speedo healer fitted has it?

[Mister Fishfinger]

Has it got a larger gearbox sprocket perhaps? Or a smaller rear sprocket?

[Hooli]

Good call fishyfinger man.

Sprockets are 18-43 from memory.

[gsxbarmy]

To get it bang on Andy, only way is to fit a SpeedoHealer

https://www.healtech-electronics.com/products/sh/

[KiwiCol]

Good call fishyfinger man.

Sprockets are 18-43 from memory.

18  - 41 I think you'll recall Hooli

The Sat Nav would display the correct speed for you though wouldn't it?  Is this where you're getting the '9mph slower' reading from on the speedo display?   If so, then I'd be checking the above, sprocket tooth count & follow the speedo pickup wire to the plug, check to see it hasn't got something else plugged into it (speedo corrector of one sort or another) as well.  There are a couple of different brands of these & each has different ways to program it to function correctly. 
Have a check & let us know the outcome & we'll see where to go from there.

[Dell Boy]

Checked both sprockets and drive chain, as that was my first thought but all correct. Checked the pickup and rota on the gearbox all seem OK. Also checked the wiring again no visible fault showing up.

[KiwiCol]

Good job, well, a speedo corrector will fix it, Dave has posted a link in a previous post. I use a different brand than Healtech, can recall it at the mo, USA thing. works great & is easy to adjust / program.

Found the one I use, 12 O'Clock labs

http://shop.12oclocklabs.com/index.php?route=product/product&product_id=59

[seth]

Ours reads about the same I know it so a just my speed to compensate.
70mph I do 80mph on.my Speedo
60 I do 68
50 I do 56
40 I do 44
30 I do 30
Works ok

[Hooli]

Good call fishyfinger man.

Sprockets are 18-43 from memory.

18  - 41 I think you'll recall Hooli

You may be right, it's a couple of years since I changed them.

[gsxbarmy]

When I had the Healtech fitted to my 14, I needed to set the adjustment to 87.5% - this being the accuracy of the OEM speedo - to get the correct reading as my speed - compared to my Sat Nav - was very similar to Seth's (above).

Suzuki speedo's are known to be "about 10%" out. Just the way it is.

[northern]

Ours reads about the same I know it so a just my speed to compensate.
70mph I do 80mph on.my Speedo
60 I do 68
50 I do 56
40 I do 44
30 I do 30
Works ok

14's speedo is not linear - it's quite accurate up to 50km/h and then difference get bigger and bigger. @Thommohawk post table in the past (possible at old forum). In this situation, SpeedoHealer cant make it right for all speeds...

But odometer is linear and quite precise, so I ajust my (have -1 front sprocket and 55 height rear tire) SpeedoHealer to show correct distance, and do not care about speed to much

[seth]

My speeds weren't set using a Speedo healer.
I just sat at the speeds I said and noted the actual speed using a GPS.
I first noticed my Speedo being so far out when in a 40mph average speed camera zone for road works I was sitting at 42ish and a bus was getting very upset as he wanted to go faster my real speed was nearer 34mph .
So I did the test using my GPS at all the common speed limits and now sit at the speeds I said .
As then I'm always within10% of the speed limit usually below especially in a 30 as there isn't really any need to go fast in town .

[northern]

@seth , I just use your numbers, to confirm changes are not liner

[seth]

All good buddy