OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S 550 EX

I have a Briggs 550EX 140cc ohc motor that I have to hold my thumb across the inlet to keep it running. I think this indicates it has an air leak but there is only the 2 "O" rings on the inlet tube that I can see would allow any air in. I have had the carb apart and I can't see anything in there that could be causing problems, it is a fairly basic carby. Something I'm missing?

Another question on these carbs, there is a rod which comes up across the front of the motor to what looks like a bulb that the rod connects to on an arm to the rear of the bulb. This I think must close the butterfly to give it the automatic choke as this motor does not have any throttle cable/control, it if fully governed. As I haven't had it running properly I have not been able to work it out

NormK,

Yes that is the choke thermal choke system.

But I need the engine numbers (Briggs standard setup of model and type) to look-up the appropriate service manual and IPL.

As if there is an air leak check that cross over intake tube, They are hard plastic and I have seen one with a hole on the back side but I still think you carb related problem but the off my head I don't remember carburetor setup the 550 uses and that why I need the model and type numbers,

Hi, Sounds like blocked jet to me - your thumb blocking off air flow acts like a choke enriching the mixture

Thanks AVB, I'm not sure where the model number would be on this one,all the top of this is plastic. I haven't seen this type of carb before.
Hi DB, I'm not sure where the jet is in this carb, it is all plastic and once I remove the float bowl there seems to be nothing else I can remove apart from the float and needle

Hi AVD the only number I have found on this cowl is a sticker with a serial number 16 0607 51 00627. The other thing I noticed is this motor is not sold in the US or Canada.

That number worked. It is a 09P702-0138-H1. On these engines the model and the type are etch into the crankcase using a series dots like Honda uses.

The carb has both an idle jet and main jet.

I have haven't dealt the ready choke on the 09P but should be the same setup as the DOV750 so including a snap from that service manual.


I hopefully can PM you several links to info on my Google drive that should help.

Thanks again AVB, I couldn't see where or how to get to the idle or main jets, there is a plate in the bottom of the carb but I can't see how it will come out, jets must be behind that somehow

The DSB 1060 I linked in the Pm should make things clearer on how to remove the nozzle assembly.

Let me know if the links don't work as I can email the info directly if needed.


DSB = Dealer Service Bulletin
APSI = Advance Product Service Informatrion

Hi Norm, once you remove the float bowl, float, needle etc, the white plastic oval shaped bit can be removed, that is where you'll find the jets and spray tube. To get it out you need to GENTLY pry it out and it's all smooth sailing from there.
Cheers, Ted

BigTed,

The DSB link I sent NormK will have the needed info in it. It also shows the new style of this nozzle that is to resolve the idle jet clogging. One thing to pay especial care of is not to overtighten the fuel bowl retaining screws [21-27 in-lbs] or they will strip out.

Thanks Big Ted and AVB, I figured that was the way to get to the jets, just didn't want to try prying on it till I was sure. There is a lot to be said for plastic carbs. Yesterday I stripped down 5 Chonda carbs trying to find one I could get apart, One I was able to get the main jet out but couldn't remove the float needle, I got the main jet and needle out of one , the rest no chance of getting the main jets out,.I'm trying to understand why these are so prone to rusting everything up in them. How does all this water get into them. This is one reason why I love the plastic Victa carbs, nery rare to find one I can't use and that is because of previous owner damage

Here I could say but over there I don't if you have Ethanol blended fuel. Here Ethanol can simply absorb moisture directly from the air and then settle out as water/alcohol mix

Never thought of that AVB but I bet you are right. These Chondas are sort of ok but everyone has this rusty carby issue and Chonda buyers are the type that would buy ethanol fuel because it is cheaper

It's the meddling government's fault they keep pushing this unwanted fuel blend onto us for their mates that have the ethanol plant.
Wish we still had oil refinery plants.

Consider this Norm, I just had repaired a Generac generator back in June and customer had use it several times afterwards. Just brought it back last week with fuel running out the air cleaner. When I pull the carb to clean it I found water and rust balls. The water I could easily explain without looking but it is the rust balls that me doing additional checks.

I made sure the tank filter screen was in place. Now there only one place in the whole fuel system that the rust could have from other than an accidental tank fill-up. That the carburetor fuel inlet tube. It was the only thing was steel. I cleaned as clean as I could and told if the rust balls showed again I need to put on a new carburetor.

This way I would have that old carburetor to try a replacement brass inlet tube idea on.

It easy to check the customer's fuel for Ethanol content. Find a 250 ml test tube or container with ml markings. Needs to seal-able or moisture from the air will affect the test. Fill the first 50 ml with water then finish filling to 250 ml line. Now cap it and shake it to mix. Set aside to settle for a few minutes. Once settle over 50 ml is Ethanol content divided by 2. Otherwords if you have now a 70 ml water line that would be 70-50 = 20 ml. 20 ml divide becomes 10 % as you using double the amount of fuel during the test. You can use an 125 ml test tube but using the larger tube uses twice the amount which gives a better and easier to read reading.

BTW be careful if you test your supplier fuel at the pump. I had one to cuss me out saying his fuel was 100% pure fuel. He stood there while I ran second test which it failed a second time. He order me off his property. But the very next day he came to my shop with an apology as he called his supplier and they tested his fuel and they came back out pumped his tanks out as they delivered the wrong fuel.

Now I not against Ethanol fuel blends just like to know that what I getting as I need to take additional protective measures with Ethanol blends like a tightly seal contain as it can and will absorb moisture while in storage. Now here a lot of techs blaming all fuel problems on Ethanol which is not the case as even as non Ethanol has additives so it can meet EPA requirements here. I would think this is the same in a lot of other countries too.

The level of Ethanol in the fuel can cause you problem especially if above 10% as many the OEM fuel parts are only tested and rated for 10% or less blends. Here in my area the EPA is introducing a 15% blend so I will see more fuel problems. All ready seen some bubbling fuel this year in those clear fuel filter on some Kohler Courage single cylinders causing running problems. The only solution was either changing the fuel or shielding the fuel lines.

Thanks again AVB, you have vast knowledge on all these things. We in the "Lucky Country" do still have a choice on the fuel we use and to my knowledge I have never bought any ethanol fuel, if I have it was by accident. Having ridden and worked on old Brit bikes all my life, one we lost our super fuel blend it was a problem so the introduction of ethanol fuel was to be avoided like the plague. There is a lot to be said about plastic carbys.