The mercury manometer is the way to go if accuracy is your greatest concern. The only error involved is going to be your ability to read the level of the mercury. Gauges can go bad or out of calibration so aren't as accurate as the mercury manometer. The downside of the mercury is that now you've go mercury in your immediate area venting to the atmosphere and mercury vapors are not good for you. I seal my mercury manometer up with duct tape when not in use as well as storing it outdoors. I still don't like having it around and am probably going to dispose of it, properly, at the local hazardous waste site and let the local shop do the sync for me.

 

I have not tried this on the VTR, but a method I have used on other twin carb set-ups is to get a pice of vaccuum hose or fuel hose, stick one end in your ear and the other down the carby. You then listen to the sucking sound it makes and adjust the carbs until the sound is the same.

This might seem dodgy until you try it, it works very well, and was taught to me by an old mechanic friend of my fathers. I used this to tune a set of twin Dellorto's that I had once.

 

A few people have pulled out an eardrum with this old time method. You don't need to put the hose in your ear canal and you should make damn sure it doesn't get in there by accident.

 

Hmmm yes, not a bad caution jschmidt. I have only ever held the hose to my ear, never attempted to poke it in there.

Anyone wanting to try this, you don't need much suction, you are listening for the sound it makes, so no need to do anything that might be unsafe.