Small Engines (Lawn Mowers, etc.): BS 22HP Engine surging, twin cylinder engines, right cylinder

Question
I have a B&S 22HP engine; model number 44677, type number 0177-E1. Just recently the engine started to surge under load at high speed.  I removed the engine housing and discovered a mouse next to the cooling fins on the right cylinder.  Afer removing the nest, changing the gas and plugs and cleaning air filter the problem still remained. The engine run normally at low speed but occasionally backfires at high. Any ideas would be helpful.

Thank you,
Mark Vermilya

Answer
This problem is almost always caused by the carburetor.  The typical repair involves removing, dis-assembling and cleaning the carburetor.  Compressed air from an air compressor works the best for cleaning the carburetor.  Just blow out all the carburetor orfices and re-assemble the carburetor.  It sounds like the carb is running lean, not enough gas getting to the engine.  This is very common with a dirty carburetor.

Also, make sure to check the intake gaskets on the twin cylinder engines.  If one is leaking it will cause the engine to surge.

Let me know if you have any other questions.
Eric