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Help!...Briggs/Nikki 2bbl Carb....

Posted by BriggsGalaxieman 10 (My Page) on
Sun, Jan 13, 13 at 16:55

I have a strange problem with a Briggs/Nikki 2bbl carb. I am open to any suggestions...

Tractor: Craftsman: 917.276080
Engine: Briggs 26hp: 446777-0244-E1
Carb: Briggs/Nikki 2bbl: 699709/791230 (Briggs numbers)

About 6 months ago I took this engine offline to repair a leaking sump gasket. At that time the engine ran perfectly. When I stopped using the engine (6 months ago) I neglected to drain all of the gas out of the carb. That was pretty dumb and I suspect that it is at the root of my problem with the carb.

I recently completed other work on the engine and attempted to run it. It would NOT run without almost full choke constantly. It would not idle. The choke has to be at least 3/4 out for the engine to run at higher rpms and even then it does not sound too good.

Naturally I suspected the carb. So, I swapped a complete carb/intake assembly from another Briggs of the same model number and known to be running good. The engine runs perfectly with the other intake/carb setup. So, I am sure that the original carb is the problem with not running without choke.

Since then, I have completely disassembled the bad carb. The only suspicious thing I found was a slight obstruction of one of the main jets. I cleared that and EVERY other passage in the carb. Carb cleaning fluid and air pass through every passage I could find. After reassembly I tested the carb and it still has the identical problem (needs lots of choke to run at all). I disassembled again and did not find anything suspicious. Every passage seems clean....

Any suggestions? What would have to be wrong in a carb so that it would require full choke to run?

Any help would be appreciated....

Thanks,

Galaxieman


Follow-Up Postings:

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RE: Help!...Briggs/Nikki 2bbl Carb....

O ring fit. Namely the ones on both sides of the plastic fuel pick up tube. Also know that there is a right and a left jet- they are not the same when disassembling. Does the fuel solenoid work as it should?
There have been a few that leak at the seam of the plastic intake manifold- if this is the version you have. I can't say that I've seen one create that drastic of an issue-but it is worth a check whilst it is off.


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RE: Help!...Briggs/Nikki 2bbl Carb....

tomplum,

Thanks for your inputs....

1. O-ring fit - The plastic fuel pickup tube is sealed at the top (casting end) with a seal that has four individual holes in it...not an O-ring. The other end of the pickup tube is sealed to a plastic ring that fits over the anti-backfire solenoid. There is an O-ring that fits between the plastic ring and pickup tube. Which one are you referring to?

2. Right and left jets?....I did not know this. But, after closer inspection, one is marked '111' and the other '114'. How do I know which one goes on which side? Having noted the difference I must say that I don't think this would cause the 'choke' problem because the carb had the problem before any disassembly. But, I would like to get them in the correct positions if you can help.

3. Intake to carb joint leak....Again, this carb ran perfectly well before it sat for 6 months. It does not seem that a sufficient leak would open up there. However I will certainly check that fitup.

Thanks,

Galaxieman


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RE: Help!...Briggs/Nikki 2bbl Carb....

tomplum,

One more thing...you also said: "Does the fuel solenoid work as it should?"

I did check its operation by powering it with 12 volts. It did seem to pull in and release, but it did seem to stick slightly. Since then I have removed it from the bowl and cleaned thoroughly. Now it seems to operate much more freely. Maybe it was sticking closed or almost closed causeing fuel starvation.

After I find out which jet goes where I will reassemble and test.

Galaxieman


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RE: Help!...Briggs/Nikki 2bbl Carb....

The main o ring that fails is the round one below the tube into the extension cup. If it is distorted, it will make a big difference. The above seal is the other one I was referring to- kind of a quad o ring. On jets, I have a cheat sheet on these I will look at tomorrow. Part # wise, I believe the odd is left, even is right. I was going to look it up online, but the distributor is updating. You are probably right on the solenoid from your description. I've had another issue w/ jets in these tubes fitting loose- which caused a rich condition however. The plastic intakes can leak at the seam is what I was referring to. Usually, they will seem mildly anemic- and can worsen as the engine warms.


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RE: Help!...Briggs/Nikki 2bbl Carb....

The 114 jet is in the LH spot. Hopefully the solenoid cleaning did the trick! These really are awesome carbs, but...


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RE: Help!...Briggs/Nikki 2bbl Carb....

OK....114 jet to the left...that will feed #1 Cylinder...I will reassmble, test and let you know how it runs with the anti-backfire solenoid freed up...

"These really are awesome carbs, but..."

But what?

One of mine has been running flawlessly since 2004, when I got it on a new tractor.....


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RE: Help!...Briggs/Nikki 2bbl Carb....

It is a good carb. They do run well and typically, the things that need to be done can be done with it mounted up yet to the engine for a quick repair. I don't like selling these kits complete and fortunately what you need is available from the distributor. Usually their issues are accelerated by water in the fuel system or the guy that dumps inna can of fix all to clean his carb. That lower tube seal doesn't like copious amounts of cleaner as it sits in the bowl. 8 years providing good service, you are to be commended. The but comes from the somewhat odd quirks that they have. One can say the same about their 1 barrel on the 28's 31's also. Some techs just don't do well with them I've found. Every so often one will get stubborn and the runability just isn't quite as it should be, plus you have odd things such as the majority of them having 2 different mains in them. Some 2 barrels have a single.


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RE: Help!...Briggs/Nikki 2bbl Carb....

Success!!!

I put the jets in the correct positions, freed up the anti-backfire solenoid and tested...it runs perfectly (no longer needs choke to keep running)

Thanks for your help tomplum...

Galaxieman


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RE: Help!...Briggs/Nikki 2bbl Carb....

I just tried to rebuild this carb, and lost the main jets!!
#111 and 114.

Is there any way to purchase these, without buying a new carb?


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RE: Help!...Briggs/Nikki 2bbl Carb....

My parts list shows the jets only included with the entire carb. They do not seem to be included in the 'overhaul' or 'gasket' kits.


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RE: Help!...Briggs/Nikki 2bbl Carb....

You can buy the jets.

Download the IPL for your specific engine from the Briggs website to get the correct part#

Google-
Briggs part# jet


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RE: Help!...Briggs/Nikki 2bbl Carb....

I'm reviving an old thread to say thanks. This info helped me a lot. When I pulled the carb on mine the two jets were both sitting loose in the bottom of the bowl, and I've been searching everywhere for a definitive answer of which one goes where.


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