Try giving Cactus a call and speak with them in person. Sometimes they are backlogged on their emails and dont always reply. But it sounds like you may not be getting the right amount of air intake into your carb. This is a rear intake engine and it requires a lot of air to run. The 240 will swing a 36x14 without a problem. I flew Bills 50% Edge in the half time at the TOC with the 240 and a bolly 36x14 and it ripped the snot out of it. More than likley you need a carb rebuild kit or more air into your carb area. You may also have a leak somewhere around the carb spacer.