# B&S Sputtering My Nightmare Help



## Banshee421 (Oct 1, 2010)

Hello all I have a 28U707 1112-E1 with a Nikki Carb in Craftsman rider. Okay it started with a sputter so I rebuilt the carb and used air compressor to help blow out ports. Assembled carb and adjust the valves, compression stroke and then down 1/4 of stroke and set the intake valves at .004 and the exhaust at .006. Well the problem is if I raise the throttle to fast the carb spits fuel out the front and the governor starts moving radically back and forth and black smoke out exhaust and the engine dies. Most of the time it is hard to restart because it is flooded. If I raise throttle slow it is fine, but then when I engage the mower deck it starts spiting and sputtering again and dies. I can control it from dying if hold the governor near idling and it will smooth out and keep running. Thanks


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## 30yearTech (Sep 14, 2006)

If your not careful with the compressed air, you can blow out the metering jet inside the carburetor. You have to blow from the inside out, if you blow from the bottom up, you will likely dislodge the jet, and if you don't have the top covered when you do this, then there is no telling where the jet might be. It sounds like from your description, that the main jet is missing.


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## Banshee421 (Oct 1, 2010)

Everything looks to be in place inside of the carb. If you look at a parts break down there is not much inside a Nikki carb . Is there any other possiblity of a problem?


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## 30yearTech (Sep 14, 2006)

Are you sure the main jet is in place and seated well? It's only held in with a small O-Ring.


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## Banshee421 (Oct 1, 2010)

I am not sure. I will have to go to the local small engine shop and see if they have the part or can help me cause I do not see it anywhere on the garage floor. Thanks for the help I will update Friday as soon as I know something


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## Banshee421 (Oct 1, 2010)

Thanks for the help, the main jet was missing ie it fell out. That Nikki Carb is very strange to me, how the float is not attached to carb and the main jet fits into the float assembly. So I got the lawn mower started and runs perfect. Thanks


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## 30yearTech (Sep 14, 2006)

Banshee421 said:


> Thanks for the help, the main jet was missing ie it fell out. That Nikki Carb is very strange to me, how the float is not attached to carb and the main jet fits into the float assembly. So I got the lawn mower started and runs perfect. Thanks


From your description of your issue, that's what I suspected. The first one of these carburetors that I worked on was also a learning experience for me. I put it back together without the jet as well, and oh well you know how this story goes... :thumbsup::thumbsup:


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## Pupatee (Jul 31, 2011)

I have the same problem, I suspect for the same reason. But where does the main jet go?

Not too smart, I know, but...


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## usmcgrunt (Sep 16, 2007)

Hello and Welcome.If you have the same carb as the original poster,this is the information your looking for.Hope this helps.

http://outdoorpowerinfo.com/repairs/briggs_intek_v-twin_carb.asp

http://outdoorpowerinfo.com/repairs/briggs_intek_v-twin_carb2.asp


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## Pupatee (Jul 31, 2011)

Thanks USMCGRUNT. That looks nothing like my carb. Mine is a Nikki from a B&S 28U707-1112-E1. But the problem is the same as Banshee421 listed. There are some photos of the carb here. http://www.flickr.com/photos/[email protected]

Any help would be welcome.

Thanks,

Pupatee


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## sail902 (Oct 5, 2013)

*Nikki Carb Main Jets*

I have the same problem with the main jets coming out of the fuel transfer tube. They won't stay in. It looks like they are supposed to be held in the "fuel transfer tube" by the O-rings on them, but they don't. I see in a parts diagram that you can buy the jets, but not the O-rings separate. The jets are expensive, about 10 bucks each and I just need the o rings. Any idea on a source for those? Also I noticed in the parts diagram that there is a LEFT jet and a RIGHT jet-- since both of my jets have fallen out, how do I know which goes where? There are some faint markings on them, but I can't make them out. Since they are right and left, I assume they are different sizes? I can't really tell.

This carb is on a JD LA145 and has been a nightmare! I rebuilt the carb a couple of times and never could get it to run rite. Did everything and all the tests several times and finally discovered a crack in the intake port of the head. Thought for sure I finally found the problem and replaced the head and it still ran bad- surging, poor idle etc. Tore down the carb for the 4th time and finally discovered that the main jets weren't seated down in the fuel transfer tube! The o ring that seals the tube to the float bowl keeps them from falling completely out


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## 30yearTech (Sep 14, 2006)

sail902 said:


> This carb is on a JD LA145 and has been a nightmare!


Please post the model, type and code numbers off your engine.


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## sail902 (Oct 5, 2013)

*Nikki Carb Main Jets.*

It's a Briggs 407777 0146 B1 with a Nikki Carburetor 795967 266, 8826N-A21 on a 2009 John Deere LA 145 riding mower. 
It's the same carburetor that was talked about earlier in this thread and pictured in a post by usmcgrunt on 7/31/11 @ 1:46pm. 

The thread talked about the main jets falling out of the "fuel transfer tube", 


Thank you, 
Jeff


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## 30yearTech (Sep 14, 2006)

Honestly, I have never replaced the jets in one of these carburetors and cannot understand why they have a different part number. I can't imagine they are different jet sizes. If the o rings on the jets leak, that would cause a rich condition, and the one you describe leads me to think the problem lies within the low speed circuit of the carburetor as that's the area that surging and poor idle are affected by.


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## sail902 (Oct 5, 2013)

30yearTech said:


> Honestly, I have never replaced the jets in one of these carburetors and cannot understand why they have a different part number. I can't imagine they are different jet sizes. If the o rings on the jets leak, that would cause a rich condition, and the one you describe leads me to think the problem lies within the low speed circuit of the carburetor as that's the area that surging and poor idle are affected by.


I found an answer to the different sized main jets in this carb. It's to balance the cylinder power, cylinder one air/fuel mixture has to travel a little farther so the jet on that side is slightly larger-- .046 and cylinder 2 is .042. Briggs part numbers 791592 and791501. I guess it's a common problem that the ethanol in todays gas eats up the rubber O-rings that hold the main jets in the plastic fuel transfer tube and then they don't seal and fall out. I haven't found a part number yet for just the o rings, but the jets are about $9.50 and 10.50 each. One guy said that he wrapped a thin ribbon of electrical tape around the jets and put them in just so that he could get the mower going to get his grass mowed and two weeks later it was still working (not recommended, but he did it on his own mower as an emergency temporary solution)


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