Alex:

As I remember turning it in raises the pressure. With your high and low needles so near shut I would think the pressure is too high.

Block the throttle around 1/2 and pinch the fuel hose next to the carb fuel nipple. If it immedialely drops RPM it's too lean, turn the reg screw in 1/8 turn and recheck.

But I'll almost bet it will pick up a good bit of speed, running rich.

You want to end up with the RPM remaining steady for a moment (or rising just a little bit) then falling off, when you pinch the line.

You should also bear in mind that YS engines have been known to have bad regulator diaphragms.

If you can't get it straightened out, and it is still in warranty, give it a trip back for a good check.

If it's out of warranty, replace the diaphragm.

Tower sells the engines, I don't know about their parts stock. Central Hobbies has the YS part you want, when you want it.

Hope this helps.

Bill.

PS: Some after run oils will attack the regulator diaphragm. wr.