20 hp B/S opposed twin surging

[AroniaFarmer]

I have a opposed twin cylinder 20 hp engine that will run great for about 15 mins and then start to surge. The surge will go away if I pull the choke a little.

 

[Egon]

Sometimes adjusting the tension on the governor spring will help??

If the carburator has adjustment screws try making slight adjustment.

 

[art]

I have a opposed twin cylinder 20 hp engine that will run great for about 15 mins and then start to surge. The surge will go away if I pull the choke a little.

With the good gas that we recieve thanks to our government we are cleaning the carbs as quick as people bring them in. I don't know for sure at this point but I might agree with it being the governor spring which is a typical briggs issue.

 

[Jerry/MT]

I have a opposed twin cylinder 20 hp engine that will run great for about 15 mins and then start to surge. The surge will go away if I pull the choke a little.

Surging is usually caused by too lean a mixture. Try some enrichment on the main jet.

 

[JRobyn]

Surging is usually caused by too lean a mixture. Try some enrichment on the main jet.

True, but OP says it runs ok for a while before it starts to surge. I'd suspect some trash in the carb that is getting sucked up in/next to the main jet after it runs for a while. Does the carb have a removable bowl? If so, remove, rinse it out, and replace.

A good dose of Sea-Foam also couldn't hurt.

 

[Carl_NH]

If it runs OK for 15 minutes check the fuel tank cap - if the vent is plugged this is a symptom I have seen - runs fine for a while then starts to stutter. Clean the vent. Then clean and adjust carb as next step..

Carl

 

[kencunningham]

Clean the carb really really good and it wouldnt hurt to flush the fuel tank and lines. If it still does it after that you should look at the fuel pump, its probably on the way out.

 

[Yandaddy1110]

Same thing with my briggs 14.5 twin. Worked on it today with carb cleaning.
Didnt help.
What i did discover though is that if the tank was full, the fuel is above the pump and gravity fed. 15minutes later, the fuel is now at pump level and the surging starts.
Replace your fuel pump.

 

[crazyal]

I would look for a vacuum leak.

 

[beandip]

Same symptoms as my B&S twin . I bought the B&S carb rebuild kit and did the rebuild. Runs smooth as silk. I used a can of carb spray with the little straw to blow out all the jets and passageways. Whole job took less than an hour.