Poco242: What model carbs have you tried on this engine so far? Is the one you normally supply with the GT25 a 13 MM size. Seems like a carb from a Zenoha G26 would be a good one. I May try the one off my Mac MB290 to see what that does for starts. Looks like I should open up the intake manifold or try a bigger one off some other engine? Let me know what you have tried. Thanks John