checking tillison pop off pressure

[Mel Ruffner]

Yes, and yes.

E.C. Distributing is the North American importer for Tillotson.  He sells a kit with an assortment of spings for the fulcrum arm.  They're smaller and lighter than anything McMaster-Carr has.
Again, I defer to Steve O for sure..  but pop-off isn't usually the first thing most people mess with when tuning a carb.  Many karters go their whole career without messing with it.
First help us understand what you have going on, and what you've tried.

Hi  Doug. When I start my Mc5 It spits fuel out of the exhaust and smokes  alot. I have the idle adjustment not even  touchin the stop, and hard to make it run clean. At the big one ,Dave pinched the fuel line and it still ran so it must of had alot of fuel in the crankcase. Thats why I was wondering if maybe I need to work on the pop off.