Evinrude 9.9/15 1989 do they last for ever? Any info on Alkylate petrol?

[driver0606]

Hello,
I have a 1989 Evinrude 9.9 hp, recently fitted with a 15hp carburetter. I do not know the history of the engine, but it seems to run well enough although rather smoky on 50:1. I have had previous experiences of other makes of two strokes where they seem to be running OK and will suddenly stop, broken crankshaft, bearings destroyed, etc. My questions are:-
1) Does this happen with the 9.9/15?
2) Are there any warning signs?
3) Rotax have a clever tool with a DTI that screws into the spark plug position and will measure the play in the con rod bearings in their ultralight motors. Is there anything like this for the Evinrude? Would it be useful or does the Evinrude not normally die of bearing failure?
4) Finally, I read that Alkylate petrol gives less dangerous fumes in the exhaust. Does anybody know about this, please?
All replies will be most appreciated.

 

[Ron Goodman]

The last 9.9 I owned was bullet proof , had a Chip in the cylinder wall near the head , I ground it down filled it with JB weld , hound it down and it ran like a champ for a couple years before I sold it to another guy and the last time I talked to him it was still running strong, they are amazing little outboards

 

[Scott Danforth]

your over-thinking it.

switch to synthetic oil for the smoke issue

run it until its dead. the motor was intended to last about 15 years of use when it was designed. your motor is 30 years old

properly maintain it, and use it often to keep it working

if you want to run ?18 per gallon fuel..... knock yourself out. the motor was designed to run on refined dinosaur squeezings, so run it. any slight benefit that Alkylate fuel would have is mitigated by it costing 5x that of normal fuel.

 

[OptsyEagle]

Hello,
I have a 1989 Evinrude 9.9 hp, recently fitted with a 15hp carburetter. I do not know the history of the engine, but it seems to run well enough although rather smoky on 50:1.

If you were just idling it, then I would say that they are all smokey. It should be fine under load, on a boat. As Scott basically said, don't look for problems where they don't exist. You will always find something but as he also said, these things are tough. Now it was not designed to be a 15Hp motor. Many people believe they can just drop on a 15Hp carb and perk up a 9.9Hp that easily. If you look closely at the different designs you will see a different throttle cam for the two motors. If this was not changed, which it usually is not, it will affect your spark timing and therefore your fuel burn and of course the exhaust smoke.

In any event, that motor does not owe anyone anything, so run her hard and enjoy the motor, would be my advice.

 

[Joe Reeves]

Do they last forever?........ In the list of outboards manufactured that are still running strong, this one would be considered a late model.

 

[flyingscott]

My 1977 15 hp is still running strong run on 87 octane. Like any other motor if taken care of will run you a good long time. The only difference between a 1989 9.9 and 15 hp motors were the carbs. The throttle cam was the same for both models.

 

[driver0606]

Thanks, everybody, that was most helpful. Are there any further comments on Alkylate fuel? I don't use a lot so the cost is not a real issue, but if it means I am breathing in far fewer cancer-causing substances while sit by the engine in nil winds, that would be a real benefit.

 

[oldboat1]

Think I would try it. Would want the premix, as dumping in some 2-cyle would defeat the purpose. If it's intended for chain saws and similar equipment, the mix is probably richer than 50:1, but worth trying. Presumably, you could lean out the mix by adding some of the unmixed version.

Would like to hear about your experience if you try the Alkylate.

 

[Stumpalump]

I burn a lot of it but it's leaded 100 octane AV gas. It burns OK in engines that don't need it but you loose a tiny bit of power and it starts a little harder. I ran it in a 2.5hp Yamaha and could not wait to get it out. It's just purer gasolene without the light components that evaporate fast and without ethanol. Those light components help it start and idle better. Not sure how your buying it unless outside of the USA. I'd run a no lead version in a heart beat if cost was not crazy and Octane is not too high. Over 93 octane will lose performance. I've tried. 89 is best. And yes the 9.9/15 and even the 6hp do run forever and ever then your kids kids can run them longer.