paulg Posted May 9, 2011 Share Posted May 9, 2011 Hi , just wondering if anyone can shed some light to prevent an old outboard from fouling the plugs after prolonged trolling... In normal use the engine is tuned quite well, but after prolonged trolling, the engine does seem to get very rough after about 15mins of trolling. The outboard is a 1982, SUZUKI DT 50, premixed 2stroke in very good condition. Will running a slightly leaner petrol to oil mix fix it ? currently running it at 75:1 Or leaning the air fuel mixture idle screw ? or altering the timing, ? I have a feeling the timing at idle is slightly on the advanced side. Any info would be greatly appreciated. thanks MR RB. Link to comment Share on other sites More sharing options...
a boat Posted May 9, 2011 Share Posted May 9, 2011 Hi, in order of importance are the following reasons for plug fouling on an old tech carby outboard- cold running engine, incorrect spark plugs and cheap oil. That engine really wants to be 50:1 and changing fuel/air mixtures on the carby will only affect the way it runs as will mucking around with timing. All of these want to be correct of course and I bet she is running cold and you are using the cheapest brand of TC-W3 oil you can find. Cheers, Huey. Link to comment Share on other sites More sharing options...
Basil D Posted May 9, 2011 Share Posted May 9, 2011 (edited) Hi, in order of importance are the following reasons for plug fouling on an old tech carby outboard- cold running engine, incorrect spark plugs and cheap oil. That engine really wants to be 50:1 and changing fuel/air mixtures on the carby will only affect the way it runs as will mucking around with timing. All of these want to be correct of course and I bet she is running cold and you are using the cheapest brand of TC-W3 oil you can find. Cheers, Huey. Huett is Yamalube 2 Stroke Motor Oil TC-W3 ok for a 90hp vro evinrude 86 model.Cheers in advance Edited May 9, 2011 by Groper Link to comment Share on other sites More sharing options...
dunc333 Posted May 9, 2011 Share Posted May 9, 2011 (edited) hi mr rosebay i had the exact same motor as you for 12 years they are great little motors,as huey said 50:1 is the right ratio ,mine did the exact same thing as yours,it use to foul plugs all the time especially if fuel was old ,try using 95oct fuel and mix it with semi synthetic marine 2stroke oil like xd 50 and you will find it will run alot better and less smokin.cheers dunc333 Edited May 9, 2011 by dunc333 Link to comment Share on other sites More sharing options...
a boat Posted May 9, 2011 Share Posted May 9, 2011 Hi Groper, any TC-W3 oil has to met a certain standard so yes it is OK to use but not the best by any means. The best oil for your engine would be XD-100 and it would burn alot cleaner and be benefical for your outboard. Only down side is the etxra cost of the XD-100 but buying in bulk can make it better. Personally the min I would use is XD-50 and as Dunc said, it too would be the best in the orginal poster old girl. Cheers, Huey. Link to comment Share on other sites More sharing options...
Basil D Posted May 9, 2011 Share Posted May 9, 2011 one more Question, I was told I should be buying lead additive for my old girl, is that true. cheers Link to comment Share on other sites More sharing options...
a boat Posted May 9, 2011 Share Posted May 9, 2011 Hi, it will run fine on good quality unleaded. Cheers, Huey. Link to comment Share on other sites More sharing options...
Basil D Posted May 10, 2011 Share Posted May 10, 2011 Thats what I thought and been using. cheers Link to comment Share on other sites More sharing options...
paulg Posted May 11, 2011 Author Share Posted May 11, 2011 Hi Gents, thanks for the replies, I am currently using the yamaha yamalube 2 stroke oil, black container with the blue screw lid. I'm not sure if this is a "cheapish" type of oil.... on the container it says to mix it at 100:1 on late model yamahas, I know the engine requires 50:1, but to prevent the engine from blowing smoke I mix it at 75:1, and i never run the engine above half throttle, so i am guessing i should be safe, please correct me if I'm wrong ... ? I must add that when i do stop to fish for an hour or so, and attempt to start a slightly warm engine, i always have to use the warm up lever... and she starts first go, (no warm up lever no start ) is this normal on this model, as i have owned previous outboards and they have never needed the warm up level on a warm or hot engine. I confrim that the correct plugs are used (NGK B8HS), but in terms of running cold, is it being suggested that the thermostat on the engine is possibly stuck open hence running cold ? thanks My RB. Link to comment Share on other sites More sharing options...
dunc333 Posted May 11, 2011 Share Posted May 11, 2011 yes they are the correct plugs .running cold means your motor is running cold.as i remember the thermo is at the top of the head and you have to take head off to get to it and in these old girls you probably will snap some head bolts getting to it.mine always started first go every time once warmed up and only fouled plugs when sitting unused for a while,why dont you get it serviced ,get a commpression test done on both cylinders they should be pretty even and go from there,take it to huey he will get it soughted for you.and those old suzis need a good full throttle sometimes just to clean them out,and if i were you i would go to 50:1 cheers dunc333 Link to comment Share on other sites More sharing options...
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