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I have a 2008 70 hp. 2 stroke that builds thick oil on the plugs to the point to clean them I have to spray with carb. cleaner and use a brush cause the carb. cleaner can't cut it. It only has 250 or so hours and has been doing this for about 2 years now. The bottom plug seems to always be the worse. When it first cranks after the rpm's lower I can put in gear and it will run with a miss till what seems to be it goes into the high speed jet. The rest of the day it'll crank and run smooth with no problems. It seems if I run a high idle for a few minutes its not as bad at first crank up. I have ran ring free and did the shock treatment and did no good. I run non ethanol gas with staybil and no difference . I do find if I put new plugs and run ethanol gas it seems to run better and the oil buildup isn't near as bad. I use yamaha oil and have never had gas more than 2 weeks old. I have pulled the drain plugs on the carbs and had no trash what so ever. I top out at 5600 rpm's but never run more than 51 - 53.... It doesn't seem to smoke like its getting too much oil but this buildup is something I have never seen before... I haven't tried to adjust the carbs . cause once it gets run it seems to be okay...I am thinking disconnecting the oil tank and mixing 50 - 1.....Anybody?????????
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Is your Primestart lever in the correct position?...have you ever checked your fuel pump for a bad diaphragm?.... -
Prime start correct....After engine is run there is no more miss at idle or any throttle position...It seems like it is not burning the oil when first cranked and the residue is almost thick as grease...I'm thinking the carbs are running rich at idle but I don't want to pull the caps on them unless I know for sure ... I don't know the purpose for the caps...I never had a motor with a capped needle valve .....It seems to be an oil flow problem to me...Like its getting too much oil at startup...Comment
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I believe there is a adjustment for the oil pump link rod, might not be it but never hurts to check it. Look in a shop manual and I think the location of the oil pump lever can be checked by eye. I doubt if its the low speed needles. Just for reference next time plugs were out I'd check compression and write it down somewhere safe.Last edited by donsmarine; 02-04-2015, 08:06 PM.Comment
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Well, if you disconnect the oil tank and run a tank of 50:1 mixture on a new set of plugs that may tell you if it's over-oiling itself with the pump/injector system?.....Comment
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