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I have a 15.5 Briggs with ohv. It backfired a couple times while it was running perfect and hasn't started again since. It backfires a litte through the intake and out the exhaust while it's cranking, but that's all.

I have a good spark. Even replaced a new plug to be sure.

I have a solid flow of good fuel to the carb. I did empty the bowl.

The compression has a letoff so there is no spec there. Briggs says turn the engine backwards and feel for recoil. There wasn't any. So I looked at the valves.

In the valve pan there was a little cup that fell off between the rocker and the valve, so I put that back and adjusted the clearances for both valves. Now there is recoil. But when I crank over I'm not even getting the backfires now.


My thoughts are to buy a $38 carb rebuild kit, but just looking for some input first. I find it odd to be running strong and then not even start and have it be the carb. I did try taking the air filter out.
 

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Did you set the valve clearances on TDC of the power stroke??

You can get the proper clearances with the Briggs Check Chart, and make sure the flywheel key is not sheared.

Best of Luck...
 

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It sounds like you had a rocker nut come loose while the engine was running.
YOu said you reassembled the rocker, lock nut and rocker arm. Make sure the clearance is around .008 for each. If you have the intake clearance too tight, you wont get compression. If you have it too loose, your compression release wont work and your starter motor won't have enough power to spin the engine.
It's very possible on that particular engine, the flywheel key has sheared (as the other guy mentioned). You will still see spark in some cases but it will be off enough to keep the engine from starting.I have seen several keys sheared on this engine family.
Dont waste your money with a carb kit. If it ran fine before, it's not going to suddenly die. You already found the main reason of the failure (rocker arm). The flywheel key got spun whent he engine backfired and died. Check the key. Good luck.
 
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