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mroman59

Engine backfire - any suggestions

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mroman59
I have a 21HP Kawasaki engine that is only 3 years old. I put it on my Simplicity 7117 as a repower project. I noticed the engine running rich as I inspected the spark plugs one day. Engine is out of warranty. Then eventually it started to backfire. I put new spark plugs in, new fuel filter, new air filter, cleaned and rebuilt the carburetor. I set the air pilot screws to factory specifications. It seems to run fine, however I cut some grass and when I turned it off, it backfired again. Any suggestions on what it could be or what to do next?

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mroman59
Thanks, I have been setting on idle before shutting it off, but I am not sure if I am letting it cool down long enough. I can let it cool down longer or choke it to see if that prevents the backfire, however I still need to check it and see if it is still running rich also. Other than that, I may need to take it in to the mechanic and tell him to find the problem.

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dirtmister16
i belive AL recently posted about this. on some of the newer engines they require shut down at near full throttle or 3/4 throttle. i belive that is what the jist of it was,due to a fuel solinoid?

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MadMike
I had this same problem with the KT-19 series 2 on my 7119. Manual says to shut it down at half throttle, which just seems wrong. I adjusted my idle speed about as low as I can, and with a minute or so of idle before shut down, back firing is gone. Mike

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cwm1276
Half to 3/4 trottle, My command backfires when shut down at an idle. Yes Al had a good write up on the reasoning. I just learn to hardly over idle the new engines, they are also design to to cool better at higher RPMs than an idle.

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