QuestionQUESTION: I have a Briggs 17.5 ohv model 31c707. I have cleaned the carb and checked all I can think of but have this problem. When the engine is low idle it runs smooth and fine. As soon as you throttle up to the point the governor butterfly starts to open it starts popping out the exhaust and intake and runs rough, almost dies. Any suggestions on this one? It has a nikki carb on it. It has fresh gas as well.
ANSWER: Hi Daniel
It sounds like to me that the valves are out of adjustment. The specs for the valves are as follows: Intake .007-.009, Exhaust .017-.019. If the valves are in spec, then there could be a buildup of carbon around the valve seats not allowing them to operate properly. Hope this helps.
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QUESTION: Can you double check my specs on the clearances? Model number # 31c707 Type # 0175e1. Those clearances seem awful small.
ANSWER: According to my B&S shop manual, those are the correct specs.
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QUESTION: I adjusted the valves, intake I had to go with a snug .010 due to I dont have a feeler gauge that goes to .009. Started the engine up and still have the problem. It is puffing white vapor out of the carb when it is doing this. I pulled the head and saw blow by on the intake valve so I reseated both valves and adjusted the valves. This is starting to get on my nerves, I have never had one fight me like this. Could it be a carb adjustment or something we are missing?
AnswerDid you check the head gasket for damage? Also you might try backing off the adjustment on the intake valve a little bit at a time and see if that corrects the problem. Also check the flywheel key for distortion. This could cause the timing to be off.
