An awful lot of the carb and running problems on the board could be solved by properly balancing the carbs.

I'm not going to go into great detail about how to do that (the single screw between the carbs), but I'd like to show you the simple carb balancer I use. I got the design from a guy on the BMW list ages ago. It is a bit unique in that has adjustable sensitivity. This allows the whole thing to be reasonably sized, and allows the use of coloured water as the indicator.

The adjustable sensitivity comes from the aquarium valve at the top, between the two legs. By opening this valve, you can equalize the vacuum on both legs. As you clowly close this valve, the sensitivity to differences in vacuum between the two input tubes increase, allowing you to balance the carbs finer and finer. Fully closed it is far more sensitive than any vacuum guage or mercury carb stick.

The tubing is just 1/4" OD ( 0.170" ID) vinyl tubing from the aquarium shop or auto store.

If you accidently suck the water through the engine, it is fine. You'll just get a little water vapour in the exhaust.

Thanks Kevin  
I have stolen a copy of your pic and instructions from Rashad's topic so when the time comes to do mine I won't have to deal with a mechanic.

Thanks man, the sync tool I have is junk.  Just won't get the fine tuning. It takes about one turn or more of the sync screw to see any reaction.

This I'll have to copy and try.

Paul

Thanks for the picture, Kevin.

I've been meaning to request a picture for quite a while, to go with your verbal descriptions.  The crucial part I was missing was how the aquarium valve was connected into the "circuit".

Now it all makes sense.

This is a fantastic idea.  I know this thread is almost 3 years old but it's still the most elegant solution I've found here for do-it-yourself carb synchronizing.  One thing that I can add is that it might be a good idea to set up a box fan or desk fan blowing on the engine to keep it cool while doing this test.