Suzuki 2 Strokes

We all know that the air screw is a tapered needle that modulates the air that goes to the pilot jet and changes low speed mixture.

My question relates to HOW that air gets from the bellmouth to the pilot jet. I have a set of three carbs which originally came from 3 bikes and there are three drillings. The center one goes to the needle jet, one is closed off with a ball and the other goes all the way down to where the pilot jet fits. Obviously the open one is for the pilot jet.

I wasted way too much time trying to work out why no air could get through the side drilling on any of the carbs.

So I checked the drilled hole for the air screw and it goes through the blanked off drilling into the main jet air passage.

It turns out that the drilling connected to the pilot jet is the one with the brass ball closing it off at the intake end. Air appears to pass from the main air jet to the pilot jet hole and goes from there to the pilot jet. And how exactly did Mr. Mikuni and his tireless band of helpers think we would ever clean that out?

I guess that no one expected us to be messing with these things 40 years later.

On this set, 60 minutes at 60 degree in the ultrasonic bath followed by Berrymans douche seems to be working.

I had expected the starter jets in the float bowls to be blocked and I wasn't let down, but this was an interesting new wrinkle.

Not that this makes you feel any better Richard but you could drill that brass ball out and put in a grub screw with o ring seal. This way you can get into the cross drilling if need be for cleaning.

That is true. In an extreme case that might be necessary. I managed to get this set cleaned up, but it was an interesting wrinkle and not immediately obvious.