Guys,
You don't need crummy primer bulbs or heavy fuel pumps to prime diaphragm type carbs. I got fed up with the primmer bulbs many years ago, so I tried something different. I believe Ozzie has tried this after I told him about it and it's working for him too.
I ran a separate fuel line directly from each engine to the fuel tank. I drilled slightly smaller holes than required, and forced the lines through into the tank. A weighted Lazair fuel filter (the metal strainer style with the check valve ball) is then attached to each so that it can flop around a little on the bottom of the tank. Keep the fuel line routed so that there are no dips in them where fuel vapors can collect, just always going higher till they reach the carb. A third hose it installed as a vent. I used an automotive tire (tyre for you guys up North) valve stem, the kind they use on alloy wheels that attached with a nut inside the tank. This vent line is routed up and forward, and allowed to hang down at the end so the pilot can turn in the seat, reach it, and blow into it. In this vent line, up under the boom tube, a one way check valve is installed. I found mine at an RV parts store. It was sold for use in a water system, and cost less than $10 buck, IIRC. The fuel tank cap is not vented.
So, to prime the engines, all you do is reach under the boom tube, grab the vent tube and blow into it. You will see the plastic gas tank expand slightly, and it will stay that way after you have finished blowing into it. Now, when you pull the starter ropes and spin the engines, fuel will be "pushed" up the lines to the carbs exactly as if you had a primmer bulb, but you don't have the crappy things anymore to fail and get stiff. The check valve I used has a rubber flapper in it, but since it's so far away from the fuel, it's never failed.
Usually, it's not necessary to re-prime the carbs by blowing in the vent after the first time each day. If you do, just grab it and blow into it. I can easily reach it while seated in my Lazair. The check valve has never restricted the carbs ability to get fuel out of the tank on long flights.
I like it because it's simple, inexpensive, reliable and light. People can look at you kind of funny as they are trying to figure out what in the world you are doing blowing into the little tube...
Chappy