Dyno jet kit?.

[Itchy]

In this day and age with FI being standard on many bikes , erm what exactly is a dyno jet kit? ,

I was flicking through an old busters catelogue, and saw dyno jet kits still being sold for old carb machines , and years ago looking at bikes on auto trader as well as the usual tarty additions say braided hoses , non std can crash bungs lots of people also advertised dyno jet kits.

just curious as to what they actually are?.

(note my CBR was rejetted prior to my ownership its why it doesn't have the little flat spot at 5000ish RPM), Bill which we swopped bikes for a bit also noticed it wasn't there either.

any thoughts?

Ta
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[Wafer_Thin_Ham]

I presume it's a box full of different jets and needles for your bike's carbs so you can swap bits in and out to get the ideal mixture.

Correct me if I'm wrong though.
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[bish777]

Indeed.

They are a kit of jets and needles, to allow you to adjust your carbs to suit aftermarket exghausts and fitting individual air filters (pod filters).

On where a FI setup uses injectors to spray the orrect amount of fuel in, carbs use a tube with a main jet (basically a small plug with a hole drilled in it-bigger the hole the more fuel and therefore richer) that is blocked with a needle of a particular shape. The needle is raised and lowered in the tube to adjust the amount of fuel entering the engine. The profile of the needle adjusts the amount of fuel for a given throttle opening.

If you put individual air filters and a race pipe on a stock bike it will run very lean as far more air is getting in and gases being expelled quicker. You need to swap the jet for a larger one and a needle with a better profile will allow the bike to run properly.

It is worth noting that carburettors are really not inferior to fuel injection-they are simpler and easier to maintain-and adjusting for a race pipe can be done for a few pounds if you know what your doing. The reason FI is used current bikes is mainly emissions control, it is easier to run the bike lean (and therefore with less of the emissions the green squad dont like).
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[veeeffarr]

Yeah it's just a square box with loads of different size jets in

Sometimes you have to drill your carb slides I think, there's another company that makes kits where you don't, but I can't remember the name.

FI bikes use powercommanders by the way, made by Dynojet (I think) that piggyback on the bike ECU and adjust the fuelling that way.

T

[Wafer_Thin_Ham]