>They know how much fuel they are supplying per throttle >opening and know
where they want the butterflies for that >amount of fuel.
Agreed , but i think the fuel injected , versus, the throttle position , is
only a basic setting , as the O2 sensor ( exhaust sensor ) plus others ,
determine the final amount of fuel injected , to obtain the theoretical
air-fuel ratio of 14.7/1.
Since the O2 sensor is the only one that receives the mixture strength .
It follows that the butterfly positions need to be the same for all four
cylinders , ( balanced ) , as the O2 sensor only gets the overall mixture ,
and can not tell if one of the butterflies is out of sync to the others .
The air screw only sets the balance at tick over when the butterflies are
almost shut to obtain smooth running.
As the throttle is opened , the balance relies more and more on the
butterflies than the air screws.
So the butterflies must be in sync at all times.
With a bike that runs on carbs , the butterflies can and do go out of
adjustment , so they are rebalanced during a service.
So surely ours can do the same , as they have adjuster screws , and they are
not fixed in place.
>It was mentioned that syncing the butterflies addressed mid >throttle
issues. That is true that it could, but whether the results >are
quantifiable or not has not been proven.
A bike that is in sync at all throttle openings has got to run better than
one that isn't , as all the cylinders will be pulling their own weight.
>It is airflow into the cylinder that needs to be adjusted to make >sure all
cylinders have proper air to fuel mixture. Since the fuel >delivery is
constant, adjusting the airflow to compensate for any
>deviations in vacuum seems acceptable.
The airflow is mainly controlled by the butterflies.
>Yamaha does not mention any specs for setting air screws.
They do under throttle body strip down.
They say it is "the standard position" , which when the butterflies are
perfectly balanced gives adjustment either way , as i see it.
>The amount of fuel delivered through the injector is a constant, >relative
to throttle position.
That's correct , but the injectors could all be putting different amounts of
fuel in at a given throttle setting , due to the fact that they can be
adjusted independently .
TO SUM UP ..
What you are saying is about right on most facts and will probably
be how most listers will see it.
But i like to get everything spot on as spot on can be and then some , and
then a bit more .
I think i might be on for an SA number with this last statement.
>Someone erroneously stated it would be the same as changing >the rear
sprocket.
I'll put my hand up to this , I'm wrong and your right.
I thought that the sixth gear would have a different ratio to our fifth ,
that's why i said about changing the rear sprocket.
All the above is not ment to offend and i hope you don't see it as so.
I'am just saying how i think our bikes work and replying to what you have
said.
If you do feel offended then i am sorry , it was not how i intended it to
come across.
But my wife says " i always get my words wrong " .
She says " i am trying ( Very ) "
atb Nick T
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