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I have a 2004 Yamaha 90HP (four stroke) with about 40 hours on it and, fortunately, it starts very easily. However, it produces a very large puff of white smoke (not steam) on a cold start that seems excessive. After it runs for about 30 seconds the smoke goes away and it is smoke free and runs flawlessly. Can somebody speculate on what's going with all the smoke on such a young engine?
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I realy do not think that you have any problem. -
EyeBee,
I was hoping someone with "hands-on" experience
would respond to your question since I have never owned a 4-stroke myself. So, I will give you my .02 worth anyway.
Obviously a small amount of oil is getting into the combustion chamber prior to startup. It can only enter the chamber by way of the rings, the valve guides, or the intake manifold. It could be doing this as your trailer the boat to the ramp and the motor is tilted up. Oil could be leaking into the intake manifold, or maybe even past the rings, which probably are not seated completely just yet.
I would try letting the motor rest in a vertical position on the driveway for a day or two and start it then with the ear muffs and see if that makes any difference - that would tell you if tilting the motor might be the cause.
Have you checked with the dealer? - you are still under warranty. I don't think there is anything seriously wrong with the motor, unless this condition worsens as the motor "breaks-in".
Good luck, and let us know what you find out,
Ken K [img]smile.gif[/img]Comment
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ive only owned 2 strokers, but i would ASSUME that as long as your compression is up to par you have no worries.keep us informed.Comment
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The Four strokes need to be trimmed up a little. If trimmed down all the way or even level the oil on the backside of piston will puddle and seep past rings into combustion chamber causing smokeing on start up. Trim the engine up enough(above the level position) so oil will drain back into crankcase.Comment
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boats.net - tilted the engine up as advised and guess what? IT WORKED!
THANKS!Comment
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Good, glad to hear it we do get that question a lot and I love it when they are easy to resolve.Comment
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I'm a newbie here but I can rest your fears about this "puff" of smoke on start up. I have 390 hours on my 2004 Yamaha F90 and it has been giving me the puff since it had 70 hours on it. I actually called Yamaha on this and they asked the following questions:
1. Is it still smoking after 20-30 seconds?
2. Is it burning excessive oil?
3. Is it fouling plugs?
4. Is it running bad?
Answered "No" to all and they said not to worry about it. There is a guy "down da bayou" with a Four Stroke 60 that does the same thing.
Usually the puff of smoke is only on my first start of the day if it does happen...
I may go 10 starts with no smoke and on the 11th start I'll get the white puff of smoke.....but it is still a LOT less than my old two stroke on start up! Heck, even the mosquitoes could not stand my old two stroke!Comment
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