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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 28655
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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Briggs and Straton 17.5 31c707 broke piston rod. After

Customer Question

Briggs and Straton 17.5 31c707 broke piston rod. After inspecting thoroughly the other components, I replaced the rod. inserted the cam with dots matching, adjusted both valves at .004" and the engine will only backfire. double checked several times the valve settings and still no run. Also replaced flywheel key. Still seems to have major timing issue.
JA: Can you guesstimate how old the engine is? And has it done anything like this in the past?
Customer: According to the code, I believe the engine is nine years old. The owner drained the oil but forgot to replace the oil and started for about 10 seconds when the rod broke.
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: I have had the engine apart three time checking assembly
Submitted: 1 year ago.
Category: Small Engine
Expert:  Curtis B. replied 1 year ago.

Did you check the valves when you had the head off? You may have a valve that is bent and not seating. Do you have good compression?

Expert:  Curtis B. replied 1 year ago.

I see question is still open, did you see my response? Did you check the crankshaft drive gear when you had engine apart? Crankshaft gear has key that could have sheared when the rod broke, this would throw off the internal timing.