Yamaha 2 stroke 50/70/90hp common carb problems wont get up on plane limited rpm

[@duraluminum]

So does the black rubber plug have to fit snuggly in the hole? The one in my middle carb falls out easily.

[@Boaters_hub]

@@duraluminum it should fit snuggly yes. It should not fall out. But if i recall when you put the float bowl back on it holds up on that rubber plug. To test this theory take a paint pen and paint the under side of the plug and install it. Than press the float bowl back into position. Gently pull the bowl back off and check for paint mark inside the float bowl. Are you having running issues?

[@brianbichanich6085]

What does the little black plug do no one I know seems to know it’s purpose

[@Boaters_hub]

Yes i do actually. They are very important. In the manufacturing process yamaha couldn’t get a jet in the body of the carburetor without machining a spot to put it and access it when servicing so they came up with the rubber plug. So the rubber plugs job is to NOT let any per say unregulated gas through and into the jet. It first has to pass through the rest of the carburetor to be “regulated” to the correct amount before exiting the carburetor. Hopefully that makes sense and helps 👍

[@brianbichanich6085]

Ok that explains it thank you