My Lawnmower Forum banner

B&S Nikki carburetor

2783 Views 3 Replies 3 Participants Last post by  bwdbrn1
My riding mower has a B&S 13.5 hp engine with a Nikki carb. The problem is the carb leaks gas out the vent holes through the card and into the cylinder. I have rebuild the carb with new seals needle the whole nine yards. And it still leaks thru the vent holes. What gives? What am I doing wrong. Please help. Thanks
1 - 4 of 4 Posts
Sounds to me like the float is out of adjustment and allowing too much fuel into the bowl. Also, did you put the needle seat in with the correct configuration?
The float floats and the needle seats properly. I filled the bowl with gas and it didn't leak out the needle but it did start to flow out a couple other holes in the top of the float housing which look to me like they are vents into the top of the carb. Then it will flow out the vent in the near the choke. Could the gas cap be letting to much air thru pushing the gas straight thru the carb?
The float needs to be adjusted. It's purpose is to control the flow of fuel from the gas tank. If gas is coming out of the vent hole on the top of the carb, and other places, then the float valve isn't sealing as it should to stop the flow of fuel from the gas tank. There should be a tab near the float pivot that could be adjusted to allow the float valve to move up further, and close off the flow of fuel.

Take a look at these. One of them might help clarify the issues you're having with your carb.

Small Engine, Lawn Mower, Snowthrower Troubleshooting, Repairs and Safety
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.