Nissan NS8B runs only on full throttle discharges gas through exhaust

[Salty and Free]

Just bought this motor. Didn't check it out enough. Starts easy 1st or 2nd pull. Only runs bad and slow at full throttle. Mixture screw on carb has no effect one way or the other. Intermittently it will rev high and clean sounding but only for a few seconds. For about a minute or two it seemed almost normal and got it down to a normal good sounding idle. Then right back. Moments of almost acting good are at best 5% of running time. I am running it in a barrel and after a short time creates thick slick on top of oil and gas. Please help. Thanks for reading

 

[pvanv]

Change plugs. Make sure you are running 50:1 fuel/oil mix. Clean the carb. Start with pilot screw about 2 turns out. There will be leftover oil in a barrel for sure.

 

[Sea Rider]

Go per Paul's recommendation, don't test OB on a barrel other than idle for short time periods or will be cooling OB with hot water, besides having a unwanted oil dressing oiling through entire OB.. Adjust mixture & idle screw with combo on water after OB has been sufficiently warmed up. Adjustments done on barrel will tend to vary once OB works on water..

Happy Boating

 

[Salty and Free]

Thanks for advice guys. Probably right about using a barrel. Turns out it was the "ignition unit", the pack that the spark plug wires come off of. I failed to check the spark plugs after I ran it. Would have found problem earlier. Pack had a little burn bubble underneath. I didnt check out motor well enough when I bought it, but I am still way ahead in the game for money invested. I will have my first test run soon! I took apart carb first which was a good exercise anyways. I want to know the whole motor. I love this web site and this forum. I will be using it a lot I'm sure. And I really dig Nissan outboards now.