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Carb Balancing drill bit confusion

Posted: Sun Feb 08, 2009 3:36 pm
by twistywizard
I am currently trying to balance my carbs using the drill bit method

Not sure I am doing it right though!!!

It says to use the idle adjuster (I assume this is the cable with the black plastic adjuster that sits below the choke?) to make a gap big enough to pass a drill bit so it just drags. I have a 1mm drill bit but this will not fit even with the adjuster wound all the way.

So I then assumed that I opened the throttle slightly so I could pass the drill bit on carb no 2, then adjust the screws on the other butterflys so they match. However doing this means when the idle adjuster knob is turned again it will change the butterfly position of number 2 and then make the others off?

So basically what the fcuk am I doing wrong here :poke: Some assistance would be great

Cheers

Re: Carb Balancing drill bit confusion

Posted: Sun Feb 08, 2009 5:02 pm
by twistywizard
I *think* I may have done

Ok so I started by winding the idle adjuster all the way in (Cable with adjuster that sits in fairing) I managed to then get a safety pin slipped between the butterfly and the barrel so it dragged slightly. I then adjusted all the other screws so each butterfly was the same, I then wound out idle adjuster until the butterflys were closed and then turned it in about 1.5 turns.

Is this correct? I assume then when I bolt them back on I fine tune the idle with the idle adjuster that sits in the fairing?

Re: Carb Balancing drill bit confusion

Posted: Sun Feb 08, 2009 10:08 pm
by CMSMJ1
Yep -that sounds about right :mrgreen:

Re: Carb Balancing drill bit confusion

Posted: Sun Feb 08, 2009 10:15 pm
by Neosophist
The drill bit method is 'ok' if you don't have a proper vaccumn gauge but it isn't as accurate as all it does is make sure that the carbs all open at exactly the same time, a vaccumn gauge makes sure they all draw the same air, which in reality usually means some carbs open slightly different due to air flow etc.

Anyway.

What have you been turning? The adjust you need to turn to put the drill bit in the floats is the one on that sits in the fairing on the NC3x, this opens the throttle plates some, then you get your given too and using the carb that doesn't have adjustment screws make it just 'drag' by turning the idle adjuster, then using the 3 x adjustment screws chance the other carbs so they all just drag on the tool too.

Then they won't be too far out :-)

Re: Carb Balancing drill bit confusion

Posted: Sun Feb 08, 2009 10:20 pm
by Cammo
Yep as you've found out they don't open 1mm even with the idle wound up to max.

You've done it correctly.

Re: Carb Balancing drill bit confusion

Posted: Sun Feb 08, 2009 10:55 pm
by twistywizard
Cheers guys thought I was doing something wrong. I thought a 1mm drill would be small enough.

I do not have a vacuum gauge, I may at some point get a local garage who I know is well versed with carbs and has the kit to set them up. However as long as they are better than they were for now that will be fine. Loads of other jobs to do on it.

Ta again