OK, here's some background: 1971 Johnson 50HP. Overheated--replaced water pump and rebuilt carbs. Ran ok for a while then started bogging down. Tinkered for a while but same problem. Pulled powerhead and replaced thermostat, spring/plug valve, head gasket, water jacket gasket, exhaust cover gaskets, cleaned carbon off pistons/head/exhaust cover, dressed all surfaces, new gasket where powerhead bolts to exhaust housing, put back together. Replaced all fuel/vacuum lines and primer ball. Replaced fuel pump and spark plugs. Gave cylinders a shot of WD-40, tested compression: 170/170, Perfect! New plugs, tried to start--kind of started (spit and sputter) had a backfire then stopped. Continued to try and start, just the occasional pop and puff of smoke out of the exhaust. Tried fuel mix directly in cylinders, just pop and thick smoke. Spark tests OK, greyish sludge now coming out of exhaust, water in cylinders? I don't know where else to go with this thing other than to the river and pull the plug.<br /><br />Any help would be greatly appreciated. Joe Reeves to the rescue? 