Dyno.

[Jammy-G]

I've heard people talk about getting race cans, and having to put their bike on a dyno and get rejetted or something?

What is a dyno? I've seen things like this:

https://i10.ebayimg.com/02/i/02/2a/24/31_1.JPG

But what exactly do they do?

Cheers.
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RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours

[Big Pete]

"dyno" is short for dynamometer which is a device for measuring power output of rotating machines. There are various sorts, the most common one for bikes uses a heavy rotating drum which is accellerated by the back wheel. The power required to do this is easilly calculated if you know the mass and shape of the drum. This sort of dyno is best for transient power measurements such as through rev range or through the gears type power measurement. There are other sorts (water pumps and eddy current generators) which are better at steady state measurement and can be used to set up the fuelling/reprogram the eprom easier. the use of a dyno can be quite involved and they can be a really useful tool for tuning and diagnostics.
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[McJamweasel]

That Power Commander is an electronic jobby that plugs into the ECU on injected bikes and alters the fuel mapping - used in the same way as altering the jetting on carbed bikes.
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BCF: Be yourself, just don't be an arse.

[Big Pete]

btw, I forgot to add, the box in your photo (Power Commander) is a box of electronics which allows you to modify the fuelling and ignition timing on modern bikes, useful if you are changing pipes, filters etc or adding a turbo.
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GarageOfPower.co.uk

[G]

A dyno is a 'rolling road'. This is a device you place your bike on which has a drum where the rear wheel goes.
As you run your bike it spins the drum. The dyno machine provides resistance to the drum and thus measures how much power and torque the engine is producing.
Often other things like air/fuel ratio meters are used to determine why an engine is not producing the right amount of power.

To then tune or tweak the fuel ratios to the optimum a carbed bike can rejetted. For bikes with fuel injection a powercomander or similar has to be used. This sits between the ECU and the fuel injectors and 'interrupts' the signal, then sends it's own ones.

Note that dynojet is a company that makes the powercomander and also makes jetting kits. However this is not what people are referring to directly when they say 'get my bike dyno'd'... just a company name.

[Jammy-G]

Cheers, satisfied my curiosity

Been wondering about that for ages, never got round to asking.
____________________
RooRoo: just like the time i stuck my finger up my arse with no lube at all and she didnt talk to me for hours