x2 with Joe
When I was installing mine I found that there are a coupe of different types of spacers. The first one I bought drew air from the secondaries when installed on my carb so the only time it worked was when you opened it up. Also the spacers can be installed upside down - don't ask how I know -
If you have a vacuum gauge see if you have any vacuum at the inlet. I'm guessing no and since you don't have a road draft tube any longer it's pushing all the fumes out the breather.