Need some Briggs help

I have a 4 hp Briggs that is on the Model 404 Tote Gote that my students put together for the build off. The engine ran great on the bench. Since it was installed into the bike it will only start with full throttle and will only run with full throttle but it runs like it is holding back and smokes quite a bit. If I let of the throttle the engine dies. I checked the choke and the throttle and everything seems fine. It seems like it is something easy but I can't think of what it might be. I don't know a lot about Briggs engines. Does anyone have any suggestions?


Well-Known Member
Do you know what model engine you have?
Too much fuel is normally a stuck choke flapper or linkage is in the wrong hole or missing a return spring and or the needle valve in the carb bowl is stuck open.
If you do not know the model number, start the engine or better yet have one of the kids start the engine and look closely at all the linkages as the engine is running and note what the rods are moving under-load/vacuum. Remove the air cleaner to get a better view. It too could be clogged.
Here are the numbers on the engine 100202, 401069, 6212131. I pulled the air cleaner off and looked but it has a slide choke so there is nothing down there to stick. I did find out that one of the head bolts was loose. I know that has to be a huge part of it. I tried torquing everything down but the bolt being loose probably ruined the gasket. I ordered a new one a and will replace it and see what happens.
Look and make sure the gasket/washer is on the mixture screw. Also make sure the tip of the screw is smooth and does not have ANY bur where it could have been overtightened bottoming into the seat. If the starter clutch was not properly tightened the aluminum flywheel key will start to shear, changing the timing and screwing with the way it runs (a lot).