Thread: Help! O.K Cub 074
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Old Jul 27, 2012, 09:01 AM
Andrew0820 is offline
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Western KY
Joined Sep 2003
1,666 Posts
Your fuel blend is just fine --- the lubricant package is very appropriate for this engine.

Since your engine ran fine for five runs, seems to have good compression and has a new plug, there are two other possibilities that come to mind.

The most likely problem is that you have gotten some trash blocking the needle valve seat or picked up a hole somewhere in the fuel line and it's sucking air. Since it only backfires, it sounds like fuel starvation. Try completely flushing the fuel system and replace your fuel tubing.

The second situation, but less likely, could be a bent connecting rod. This lowers the compression and changes the timing of the engine. The only way to find out is to disassemble the engine and visually check the rod. Also check to ensure all screws, nuts, etc. are tight -- sometimes, after running a bit, parts can loosen up.

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Last edited by Andrew0820; Jul 27, 2012 at 12:07 PM.
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