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Discussion Starter #1
Briggs 445577-1187-B1

Someone had previously pulled the car apart to clean it, and said it didn't work right after assembly.

I pulled the carb apart to find that the two jets fell out of the emulsion tube :(

My problem is that I don't know which side feeds the number one cylinder. one jet is bigger than the other. one jet has #173 the other #176. I also describe it as cylinder 1 rather than left or right because it would depend on where you stand to call it left or right.

Seems as though that would make more sense.

I would also think they should fit snug inside rather than just fall out... Am I correct in thinking that?

Any help would be greatly appreciated.

Thanks
 

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All the ones Ive seen, just kinda sit in there, and the emulsion tubes hold them in place when the thing is assembled.

Never seen them, or noticed one, that had different jets though...
 

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Discussion Starter #3
Thanks for the info red. I was hoping you'd know about the different size jets. Even the part numbers are different in respect to left vs right. Not sure why they would need to do that, but I've read a couple other stories with the same basic situation with the same carb. unfortunately, the jet numbers themselves were different than the ones I have so I'm not sure which one was the bigger in their case. Ive done quite a few of these (very similar) on kawi's, and never pushed/pulled the jets out seeing as how they are easily accessible as well as to clean. That being said, Ive also never had them just fall right out on me either. Usually in the cases I have seen/done, they are relatively snug in the emulsion tubes. My only worry would be if the o-rings are going to let fuel past them if they are not tight enough, causing it to run rich. Hopefully someone else may have the answer.

Thanks
 

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The #2 cylinder always gets the richer (larger numbered) jet, because the air/fuel mixture must travel farther from carb to cylinder on that side, and it inherently tends to lean out during the trip as a result. Briggs engineers compensated for this lean-out problem by spec'ing a richer main jet for the #2 cylinder on these engines. Kawasaki two-barrel carburetors are usually set up the same way.

Now about those jets falling out over time...unfortunately, the 797890 carburetor overhaul kit this engine takes does NOT come with new O rings for the main jets. The O ring around each jet is the only thing holding the jet up in its plastic orifice in the tube. You are right about the jet being supposed to fit in there snugly. They ought to press in and stay put. However, when today's ethanol gas finally gets to the O ring, it shrivels up and the jet falls out. Whenever I rebuild one of these carbs, I always order a kit and two new main jets. They are about $ 8.00 a pop, so its not a bank-breaker, but you have to replace them when the O ring goes bad.

That said, my neighbors (who are both electricians) called me the other day and said their Intek-powered Husqvarna wouldn't run. After popping the carb apart, sure enough, both jets were sitting in the bottom of the carb bowl. Not having new jets on hand at the moment, I cut up a small piece of electrical tape into two thin slivers, wrapped a piece 1.5 turns around each jet, and popped them back in. Mower is still running well weeks later. Is it a permanent fix? Nope, and I don't encourage it. But if your grass is knee-high and ya gotta mow, this fix will last at least a couple uses while some new main jets are on order. Partstee.com or your local Briggs dealer will hook you up.


Cheers!
 

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Discussion Starter #5
The #2 cylinder always gets the richer (larger numbered) jet, because the air/fuel mixture must travel farther from carb to cylinder on that side, and it inherently tends to lean out during the trip as a result. Briggs engineers compensated for this lean-out problem by spec'ing a richer main jet for the #2 cylinder on these engines. Kawasaki two-barrel carburetors are usually set up the same way.

Now about those jets falling out over time...unfortunately, the 797890 carburetor overhaul kit this engine takes does NOT come with new O rings for the main jets. The O ring around each jet is the only thing holding the jet up in its plastic orifice in the tube. You are right about the jet being supposed to fit in there snugly. They ought to press in and stay put. However, when today's ethanol gas finally gets to the O ring, it shrivels up and the jet falls out. Whenever I rebuild one of these carbs, I always order a kit and two new main jets. They are about $ 8.00 a pop, so its not a bank-breaker, but you have to replace them when the O ring goes bad.

That said, my neighbors (who are both electricians) called me the other day and said their Intek-powered Husqvarna wouldn't run. After popping the carb apart, sure enough, both jets were sitting in the bottom of the carb bowl. Not having new jets on hand at the moment, I cut up a small piece of electrical tape into two thin slivers, wrapped a piece 1.5 turns around each jet, and popped them back in. Mower is still running well weeks later. Is it a permanent fix? Nope, and I don't encourage it. But if your grass is knee-high and ya gotta mow, this fix will last at least a couple uses while some new main jets are on order. Partstee.com or your local Briggs dealer will hook you up.


Cheers!

Thanks for the info! As I said in my previous post, I've done quite a few of them on kawis but never felt the need to remove the jets. That being said I never even noticed they were a different size (which is kind of sad on my part because I'm a machinist, so I should have noticed it). I actually ordered the kit and found out (the hard way) they don't come with the o-rings, or the intake gaskets. Seems kinda stupid seeing as how they know they are going to fail:Disgus:
I was going to try to put in an o-ring from a set i have and try it out but I figured I didn't want to have to tear it back apart again after doing it.

Thanks again!
 

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FWIW, {nada} I'd think that any O-ring that would fit, and not turn into black muck, and would hold the jets in place, while sealing, would work. Who cares whether it has Nikki emblazoned on the package... They buy by size and composition of the material, so can you if you can find one {two} to fit. Only thing is they have to be able to stay in one piece while in contact with gasohol{see: Ford & Carter ha.} 24X7.
If it is your machine, and you don't worry about comebacks, go for it. The jets don't wear out... They just fall out.
tom
 

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Discussion Starter #7
Hey tom,

unfortunately its not mine, so I don't want it to come back. If it were mine I'd probably just wrap them in electrical tape as you mentioned and call it a day. It's funny how everyone around me has perfect running machines and somehow, mine always get the short end of the stick??? Thanks for the input.
 

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Discussion Starter #8
I just ordered a new set of jets, (791502 right/791501 left) and not only are the numbers on the jets different (original's were 173/176 new ones are 113/116) but according to the markings on the carb itself, it would mean the bigger jet would feed the number one cylinder. If I go by the engine left/right (viewed from the front) it would then put the bigger jet on cylinder #2. In other words, when standing at the front of the engine, cylinder #1 is on the left and cylinder #2 is on the right. when the carb is bolted to the intake tubes the markings on the carb have the "R" on the left and the "L" on the right. Not sure what I should do. Any suggestions?
 

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Discussion Starter #9
Okay , I'm an idiot. Upon further inspection, I realized that the original jets were in fact 113/116. It was hard to see, and I mistook the 1's for 7's. That said, I just installed the new jets R/L in the spots respective to the IPL and what was marked on the carburetor, and it worked perfectly. FWIW this is what I found out:

part#791501 (main jet left jet #113 .042 thru hole) feeds cylinder #2

part#791502 (main jet right #116 .044 thru hole) feeds cylinder #1

In the end the larger of the two jets feeds cylinder #1. Not sure if its like that on all nikki carbs, or what the reasoning is behind it, but it is what it is... running again.
 
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