I would like to use a perry pump on my 1.8 moki, is possible to drill thru the left up hole of the rear cap to get pressure from the crankcase?

The Moki works much better with a Cline or Iron bay regulator than with the Perry pump. With the Perry it is hard to get the mixture correct all across the range.

You will still need the pressure tap

I have never had that problem, but I have only used one on a .60 sized a couple of decades or more ago. And more recently on a .91 ASP. It does take some tuning to set up, even starting with one takes a bit of extra knack. The Cline may work better, though I haven't tried one. But if youalready have the pump, try it and let us know how well it works.

BTW, I suspect there may be some quality control problems with the Perry pumps. Not from my experiance, but from posts here, some pumps do not seem to have a working regulator, just pumps full bore no matter how the regulator is set. The ones I have had definately controlled the presssure, were adjustable, and the engine ran like a clock with it. Other seem to have a problem with the engine flooding at idle or midrange and do not respond to adjustments of the presssure regulator.

I ran my Moki 2.10 yesterday for 4- 10 min. flights with a perry pump and it worked perfectly reguardless of tank level. I previously tried a Cline regulator but never got it to work consistantly. Just drill and tap the center of the back plate and use loctite on the fitting.

Cline worked better for me. Just drill and tap the center of the backplate. Piece of cake. If you no longer need the tap, plug it using a tight fitting piece of fuel line and a tight fitting plug at the end of the fuel line.