No thats exactly what youre doing, bypassing the jets, you need to soak them in carb cleaner, Ultrasonic jewellery cleaners are good too if you happen to have one, ..cant be much wrong if it runs!
Just a thought, If its running on two and the other two have blocked jets, Then if you rev it up and give it some throttle, Then the other (Blocked) carbs should come into play throgh the main jets, this is because of the increased air flow through the carbs at the higher revs, you will feel the exhausts warm up and will run smooth...This will confirm the starter circuit problem