B&S Intek 14.5 backfire

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ghost1

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• Jun 20, 2014 / B&S Intek 14.5 backfire

• #1

Model 28S707 1149-E1

History
Ran when put away last fall
Forgot to turn off fuel and gas all ran to crankcase
Starter will now only spin engine with plug out


Have done the following
Drained oil/gas and replaced with fresh oil
Three different starters tried with same result as above
Adjusted valve clearance.. 004 Intake 006 Exhaust
Starter will now turn motor with plug in but backfires and will not start
Gas tank not currently attached.. Pouring small amount of fuel down throat of carb.

????????

 

M

Mikel1

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• Jun 20, 2014 / B&S Intek 14.5 backfire

• #2

How is the spark? What is the compression at? Backfiring thru muffler or back thru carb?

 

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ghost1

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #3

Spark is good.. Compression 150.. Backfiring through muffler.. Also have checked flywheel key and it's in good shape.

 

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gregjo1948

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #4

I know you already set valve lash but I think you should check it again. I would set both in/ex at .004". Not sure on this engine but many have a built-in compression release to ease the cranking. Be very sure on the exhaust adjustment. It stays open or re-opens momentarily when the intake is opening. If the clearance is too much it won't allow compression release and will hold exhaust emission and cause fumes in hot exhaust system to fire.(backfire) Try setting exhaust and checking in several spots as you rotate the engine to be sure. gregjo1948

 

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ghost1

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #5

Will do.. Just came in from checking again and it was a tight .004. It gives one heck of a backfire when choke is activated, then that's it. Will advise after checking gap at different rotation.

 

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ghost1

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #6

Checked gap at several stages of rotation to make sure .004. Same results.. One loud backfire from exhaust when choke is activated.

 

G

ghost1

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #7

Could head gasket cause these symptoms ?

 

Fish

Lawn Pro

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #8

Take the valve cover back off, and take the plug out, and carefully watch the valves while turning the flywheel by hand. Also make sure that the valves
are both coming up to the same height when the rocker arm isn't touching them.

 

M

Mikel1

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #9

Did you replace spark plug?

 

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ghost1

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• Jun 21, 2014 / B&S Intek 14.5 backfire

• #10

Spark plug was changed... Went ahead and pulled head. The gasket looks in pretty good shape with no apparent blow by. Both valves appear to be making contact with seats. The exhaust is very gummed up with carbon and took some effort to extract from head. Will replace gasket, lap valves and see if that may have been the problem.. Anything else I might look for while head is off???