Hello. I did a seafoam treatment on my motor yesterday. I made a batch of seafoam/oil/gas mix, sprayed the cylinders the night before and started it up on the lake yesterday morning. I let it warm up to op. temp. let it sit for 15 minutes started it up and still no smoke. I had it going from idle to wide open. Does this mean I don't have a carbon build up or was the seafoam expired? When I say no smoke I mean only the normal amount. I also did a 4 HP Johnson at the same time with the same, no smoke, result. Thanks, Rick.