Mikuni Carb ~ Drain Screw

[Garn 1]

I'm having trouble with two of the bowls of a Late Z1A /Z1B (small) brass drain screws.
The screws are OK, however the bowls look as so they have been drill out, leaving some of the previous drain screw thread in the hole.

What I think I need, is the same size thread that I can form up a rough tap, by either grinding tiny grooves in it, or by making a "D" shaped tap!

The thread size is most unusual nom..... 6mm and about 0.75 Pitch.
Actual size of slightly worm thread, say...... 5.90 mm.
Looked up thread size via Google ...... It appears it's a metric fine M6-0.75

Size(mm) Pitch (mm) Tap Drill(mm)
M6x0.75 ...... 0.75 ............ 5.20

Anyone, know of a steel threaded section with this tread somewhere else on the Mikuni Carb. Alternative can I buy a tap?
RegardZ.

[Garn 1]

Thanks for answering your own query Garn,
I was able to purchase a 6mm x 0.75 pitch "Metric Fine" tap.
Tapped the old broken-off screw out and we live again!

Tap was purchased locally from ..Graham McDonald Services P/L
PO Box 86, Pendle Hill, NSW 2145..... Australia.
RegardZ.

[Jay1969]

Well done Garn