I thought I had already replied to this post...I guess it didnt go thru. Anyway, bihira talaga sidedraft na multi-barrels dito sa atin. Usually kasi nasa mga 70's, early 80's high-end sports cars and multicylinder bikes, both of which are rare here. I must admit, mahirap i-diagnose ang mga side draft carbs lalo na kung multi-barrel. It takes time and patience to really figure them out. For one thing, they are more complex than downdraft (fixed venturi) carbs and they have 3 different jets for various modes of throttle openings. Compounding the problem is the fact that variable venture carbs(aka sidedrafts) are dependent on engine vacuum in metering the fuel to be mixed with the incoming air which makes them more prone to uneven Air-Fuel Ratios between the individual cylinders.

Here are a few options/suggestions:

1. Go to bike repair shops that specialize in multi-cylinder, chop-shop bikes. They should have better experience than most anybody else when it comes to multi-barrel sidedraft carbs.

2. Overhaul the carbs, make sure everything is matched between the 2 barrels (jet sizes, etc.). Replace old gaskets to make sure of no vacuum leaks.

3. Check out this website and see if you can figure out your problem.
http://www.factorypro.com/tech/carbt...m_engines.html