How do you access the left hand air screw (e.g. special screw driver) with the air box in place?
A long screw driver will do for the right one but what about the left?

Always found removing the air box best.
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If I have to take the carbs off once more...

You are probably right, it's easiest with the airbox of. But wouldn't the removed air box change the air fuel mixture and give a false setting when searching for the highest idle rpm (= optimum setting)?

The amount that the air box enriches the mixture at idle is very little and not a worry for a road bike in most cases.

If the best possible set up is required then the stock air box needs removing anyway and the HRC item fitting.
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If I have to take the carbs off once more...

I drilled a hole in a pair of airscrews then soldered in some 1mm clutch cable. Made the cable long enough to come to side of frame. Then made a little knob for each end. Now i can adjust the mixture anytime.

Funny thing is, when i mention this to Matt at tyga, he sent me a pic of same thing that he did years ago.

This is without a doubt the way to go. Perhaps some motivated entrepreneur can make some for a small profit.

@Stephen: I guess you are right. I could check by opening the airbox and removing the filter while the engine is running. If my digital tacho doesn't change, that supports your opinion/experience.

@ericandchi: Great idea. I was thinking about soldering a knob to the brass screw (as can be found on the Internet) but reckoned there would not be enough space for my finger on the lhs screw. Adding a few cm of control wire from a bicycle brake between the knob and the screw should help. Thank you.