Hey Guys! Anyone having trouble logging in drop me an email, still a few bugs with logging in!

Briggs Carb - no idle mixture adjustment

Carburetors - adjust, rebuild, repair, etc.

Moderators: Old School, harryparatestis

Post Reply
Posts: 79
Joined: Wed Sep 21, 2005 8:08 pm
Location: Mb. Canada

Briggs Carb - no idle mixture adjustment

Post by MachJeff » Thu Feb 28, 2013 5:04 am

I have a Briggs & Stratton lawnmower motor I'm trying to get running - not in a Kitty right now, but it might be a problem someone here can help with.

I can get the engine to run great at WOT, but not idle. It only starts if I prime it, and will only come close to idling if fully choked.

Problem is this carb is factory jetted for idle mixture and there is no idle mixture screw. Near as I can tell, I'm not getting any fuel in the idle circuit.

I have replaced the needle, seat and what few gaskets there are. Have also cleaned it several times and tried to work through all the ports.

Does anyone have a suggestion for how I might unclog the idle circuit, or drill something out to put an idle mixture screw in it (I have one that came with the rebuild kit)?

Here's pictures of the carb for reference.

The ball plug I believe is where the fixed idle jet has been pressed in and sealed. Somewhere here is where the idle mixture screw would have been before the EPA stepped in.


There is a port on either side of the choke here. The one on the left is a breather for the bowl and is clear. The one on the right I can not blow air through or clear it out if its supposed to be.

In the center of the carb here (up in the riser tube) are two more ports. The brass one is the main fuel tube up into the venturi and is clear. The other one I can not blow air through or clear it out if its supposed to be.

Any suggestions appreciated. In a few days I may try and stop by the local lawn and garden shop to see if they're any help.


Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest