Opening Out the Pilot Outlet on Pre Monoblocs?

[Iron Head]

Thought I'd add a postscript regarding this topic having conducted some road testing. I did enlarge the pilot outlet very successfully using a neat kit bought off the web at a ridiculously cheap price (101 drills plus pin vice and case for £20). The #67 bit went through cleanly on the NOS carb body but the #66 removed metal.

Although running was good hot starting was very difficult - some gunshot sounding backfires and fast tick over problems?! On my run yesterday I had deliberately not tightened the pilot outlet screw and was doing some adjustments during the ride. Unbeknownst to me during the ride the screw did itself up to closed and perfect running (and subsequently starting ensued).

In my situation I have discovered perfect running and starting with the screw closed completely. 5 hot starts in a row every kick. Possible downside is that I now can't go any richer but the running is great and the plug the right colour.

Just my experience but my set up procedure is as follows:
- Gauze bellmouth off and check slide height with finger. Adjust slide height just so as detectable lift-off is felt.
- Start/ride bike. Readjust slide height as necessary to get steady tick over then adjust pilot outlet accordingly. Finally readjust slide height for optimal tick over.

Iron Head