B&S 27 hp V-Twin

   / B&S 27 hp V-Twin #1  

nap61

Silver Member
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Dec 16, 2006
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233
I have a 27 hp V-Twin B&S on my ztr. I cut about 1.5 acres yesterday and all was fine. This morning, I started it to cut some more and it began "surging" or cycling. The rpms did not fluctuate but the sound of the engine kept rising and falling. Also, the engine did not sound like it was running as fast as the tach was reading. I cut about .5 acre without a problem except for the surging. The air filter in new but the fuel filter could probably be changed. The gas (no ethanol) is 10 days old. Has anyone else had this problem? What was the cause? Thanks.

Norm
 
   / B&S 27 hp V-Twin #2  
Not to say this is your problem, but I just fixed my 15.5 hp B&S today for the same symptom. The float had stuck allowing gas to run into crankcase and it was trying to run on the gas & fumes from the breather tube going back into the carb.
Change fuel filter, check for water, and look close at the carb linkage to make sure a governor spring hasn't broken or popped loose.
 
   / B&S 27 hp V-Twin
  • Thread Starter
#3  
Dennis,
Thanks for the suggestions.

Norm
 
   / B&S 27 hp V-Twin #4  
Typically the surging is caused by incorrect mixture. So if the float is ok check for water in gas, fuel filter, restrictions in fuel line to carb, fuel pump vent blocked etc.
 
   / B&S 27 hp V-Twin
  • Thread Starter
#5  
Thanks. Can regular gas additive (STP, etc.)be used to help clean the carb? If not, what is the best additive to use on a small engine?

Norm
 
   / B&S 27 hp V-Twin #6  
Fuel injector cleaner or carb cleaner (gas additive) will help if it is a gum build up. With the sudden change I would look more for a restriction in fuel line or debris in the carb. I once had a cap come apart and cover the bottom of the tank. I had a surging problem on a B&S 16 hp surge and tracked it down to the fuel pump vent had caked with dust. Blew the dust of with compressed air and surging went away.
 
   / B&S 27 hp V-Twin
  • Thread Starter
#7  
UPDATE - I replaced the fuel filter and cut for about an hour and all was well. No surging. When picked up the parts and spoke with the dealer, he said not to use the regular gas treatments in small engines.
Thanks again for the suggestions.
Norm
 
 
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