The engine responds well to a larger carb such as one with an 11mm venturi. But you have to open up the throat in the plastic carb adapter manifold to match the carb throat. Often times, before you get to the point where it is open to the same diameter as the carb throat, you are either very close, or slightly into the carb pulse hole in the manifold. You will also get very close to the "relief" provided in the manifold for one of it's mounting screws. I fill the pulse hole with JB Weld, and I make a little dam and fill the area near the bolt hole relief somewhat and use a smaller headed bolt in that position. You can then bore out the manifold as far as needed without problems. Don't try to bore the manifold out with a drill, as it will catch in the soft material and probably ruin the manifold. I use a sanding drum in a Dremel.

If you look at the fuel pump cover on the carburetor, it has a couple of little raised round spots or bosses. These bosses are there for the installation of a fitting for a hose to run to any convenient spot on the crankcase for the pulse for the fuel pump. Some carbs come from Walbro with a fitting; the ones for applications using the manifold pulse hole don't. All you have to do is drill and tap the boss for a hose fitting and run a line to another fitting installed on the crankcase for the pump to operate. The fitting on the crankcase can be anywhere that is convenient, just make sure you don't leave any chips in the engine from drilling and tapping the hole.

This is a good modification whether the engine is run on regular ignition or Gas/Glow.

AV8TOR