Z1-R Mikuni VM28SS Air Screw Setting Advice Please

[pertonpc]

Hi People,

I have VM28SS standard carbs on a Z1000 D1 bike.

Factory Assembly & Preparation Manual states Air Screw position should be 1 and 3/8 turns out + or - 1/4 turn

Tried Gunson test but not very conclusive.

So I set all to 1 and 1/2 turns which seemed to be where they were to begin with.

Took her for a run and took plugs straight out - any that are a nice coffee colour I am leaving alone.

If any are paler than coffee colour I am going to slightly enrich mixture on that cylinder

Can I just confirm the following before I start fiddling with mixture again -

WHEN YOU TURN THE AIR SCREW IN TOWARDS THE SEAT YOU ARE REDUCING AIR FLOW THEREBY MAKING A RICHER MIXTURE.

AS YOU APPROACH AN OPTIMUM MIXTURE YOU WILL HEAR A RISE IN REVS

Thanks in advance from Mark

[njwmct]

Yes - turning the pilot screws in reduces the air flow & richens the mixture

In my experience on a Z1000 Mark II the revs don't rise that much when you hit the optimum mixture.

I used both a Colourtune plug to find the point & which the burn just changes from yellow to blue & my ears - if you listen carefully you can tell when the motor is running right.

Also turn the screws out a little at a time & wait a bit, as it takes the motor a little time to react.

I ended up with the outer cylinders at 1.5 turns out & the inner cylinders at 1.25 turns out.