Briggs 19 HP opposed twin jetting

Does anybody know if it is possible to get smaller main jets for the Briggs stock carburetors? I have an opposed twin on my Murray Widebody LT, and it runs rich as hell. It's gotten so bad that it's fouling my spark plugs and the smell of my clothes... And my pipes exit the mower all the way at the rear! I was thinking about soldering in the hole in a spare jet I have left over from the carb rebuild (Yes I tried that one and I get the same result) and then using different sized drill bits until it runs correctly. I have a 4" engine to 3" transmission pulley swap, and when you step on it while rolling in 5th gear from idling, it dies. Any ideas would be great.

Nick
AKA
ODOTB

I have made jets smaller by soldering and redrilling (because I goofed and drilled too large.

IF everything else is okay with the carb (and I suspect it's NOT), then I'd say your exhaust might be an issue.

I rebuilt the carb when I first got the mower and replaced all the gaskets, fuel pump diaphragms, needle, and jets. I'm going to replace the float too, every time it runs out of gas, when I put more in, the fuel pump overpowers the needle and floods the hell out of the carb. If I take it apart, fill up the bowl with gas all the way, and put it back together, and it's fine.

You shouldn't have to drill a stock jet on a stock motor, something else is wrong. Sounds like your float is getting stuck, has a hole in it, or needle valve isn't sealing right.

you could slow down your fuel pump by cutting the vacuum line that runs to it and install a fuel hut off valve but i dont recommend it does the engine start flooding its self at idle or at max RPM

Sound like misadjusted/ leaky/ too low float setting.

Or it could be something in the needle/seat holding it open.

Standard emergency repair procedure is to tap it a few times with a hammer handle or screwdriver handle.

It might dislodge whatever it is holding the seat open. Also make sure you have clean airfilter of sufficient capacity to supply air to the engine.

Chopperhed wrote:

Sound like misadjusted/ leaky/ too low float setting.

Or it could be something in the needle/seat holding it open.

Standard emergency repair procedure is to tap it a few times with a hammer handle or screwdriver handle.

It might dislodge whatever it is holding the seat open. Also make sure you have clean airfilter of sufficient capacity to supply air to the engine.

now that i think about it more it does sound like the float could be getting stuck open or the float could have a leak in it that would explain why it floods with gas would take off the float and get you a small cup of gas and lay the float in it for about 1 hour and come back and see if it sunk to the bottom or if it floats if it floats something is blocking the needle from from going all the way up

Agreed. It's being force-fed. The symptoms tend not to be as obvious in a gravity-feed system, but once you add a fuel pump to the equation, away you go. There's not too many other reasons for an otherwise stock, fixed jet system to run rich.

Frankly, if the float is drowning, it should be obvious. Hold it to your ear and shake it. I think it's more likely to be trash in the needle seat (or on the needle) or a sticking float.

okay, so I ordered a float yesterday for the hell of it. It's the only thing I haven't replaced in this thing. Every time it floods out, I blast it out with carb cleaner and then blow the poopie out of it with the air compressor. It has a new needle, gaskets, fuel pump diaphragms, fuel lines, filter, shutoff... Heck, last month I took the gas tank out, washed it out with soapy water, rinsed it like ten times, shop-vac'd it, then put a clean towel over the fill hole and let it air dry for a week before i put it all back together... The float isn't sticking, there isn't a hole in it (I check every time I have it apart) and there's no crap in the carb. The needle should not be letting loose like it is. If anyone else has seen the float in an op twin, you know that it only has air in about half of it, and the rest is some solid plastic that connects it to the needle. I think that plastic is a little bent out of shape. When the new float comes in, I'll run it out of gas, install it, try it, and update you.

Nick
ODOTB

Wow... Didn't know this forum had auto-censoring. I typed s***. LOL

OpposedDualsOutTheBack wrote:

okay, so I ordered a float yesterday for the hell of it. It's the only thing I haven't replaced in this thing. Every time it floods out, I blast it out with carb cleaner and then blow the poopie out of it with the air compressor. It has a new needle, gaskets, fuel pump diaphragms, fuel lines, filter, shutoff... Heck, last month I took the gas tank out, washed it out with soapy water, rinsed it like ten times, shop-vac'd it, then put a clean towel over the fill hole and let it air dry for a week before i put it all back together... The float isn't sticking, there isn't a hole in it (I check every time I have it apart) and there's no crap in the carb. The needle should not be letting loose like it is. If anyone else has seen the float in an op twin, you know that it only has air in about half of it, and the rest is some solid plastic that connects it to the needle. I think that plastic is a little bent out of shape. When the new float comes in, I'll run it out of gas, install it, try it, and update you.

Nick
ODOTB

please do let us know what it does after you install the float