89 Yamaha 70hp two stroke opinion

[utfyrfytr]

My 89 70hp has oil injection. Every time I start it cold it smokes like crazy for a couple of minutes. I pulled the air intake from the carbs and there is a lot of oil and gas leaking from the carbs. When I take it out of the water to trailer it home I use a transom saver so the engine sits at an angle and I assume the gas/oil mix is leaking past the carb floats while on the road. When I get it home I lower the motor and I would think that the floats should shut off the flow of fuel at that point. My question is what does everyone think about putting a shut-off in the gas line and run the gas out of the carb before removing the motor from the water. I have heard some say that running it lean during that time will ruin the motor. Thoughts, examples? Thanks to all who comment.

 

[racerone]

Run the carburetors empty.----No such thing as damaging the motor ( lean ) in doing that !!

 

[99yam40]

I would think you need to find out what the problem is.
something it leaking.

my guess is check valves on the oil system

as far as running the fuel out of a multiple Cylinder motor with multiple carbs means that some cylinders will be running lean or without oil and fuel because the lower carbs will have fuel after the top ones have run out
if you don't believe that run them dry or almost dry and see if some still have fuel when others have no or less fuel when you drain the bowls

 

[racerone]

^--Nonsense----You can not damage a 2 stroke by running fuel out of the carburetors.

 

[99yam40]

you do you and I will do me.
he needs to locate the problem and fix it,
not try to find another way around his problem

 

[racerone]

And extra smoke on start-up is also normal and a good sign on a 2 stroke !------Lubrication on 2 strokes is not well understood.

 

[utfyrfytr]

99
So you are saying that by having the motor up, in transport position, there should not be fuel leaking past the carb float needle valves and that what I am seeing is being caused by a secondary problem? You mentioned the oil check valves but I was under the impression that they only directed the direction of the flow of the oil to the carbs. Am I missing something here?

 

[Mc Tool]

I might be wrong here but I think that the Yamaha oil injection pump sends oil to the inlet manifolds so that the oil is picked up by the fuel / air mix and drawn into the motor . In any event when starting from cold the motor is fed a rich mix via the choke mechanism . Oil puddles inside a 2 stroke motor and is stirred up by the enriched mix and the fast idle producing the billowing smoke your seeing . My 90hp yam did it and I saw it as a good thing.
Re the puddling ....you may see hoses coming from the side of the motor about half way up the side of the cylinder block going to the upper and middle main bearings. These hoses come from the lower transfer port runners in the top two cylinders ( where the oil puddles ) and direct the oil to the top and middle main bearings (gravity feeds puddled oil from the lower cylinder lower transfer port runner to the lower main bearing )where it passes thru said bearings lubing them and then is re-introduced into the crankcase to have another go at lubricating cylinder walls and big and small end bearings on the con rods.
I guess in these environmentally friendly days its not such a good look and is fodder for the greenies , but its not as bad as it looks , and some oils do smoke more than others . I used Valvoline outboard oil which I feel is better than some others

 

[airshot]

I have a Mercury oil injected two stroke motor.....when starting cold, I let it crank a few times to get the oil pumping, then choke and start...the smoke tells me the system is working properly. Smoke goes away in a few minutes. You should have a quick connect on the fuel line, I unhook mine then run up on the trailer to burn most but not all the fuel out of the carbs.
When tilting the motor up for trailer ing , a few dribbles may come out, but no big deal. On occasion I wipe clean that area on the inside that collects debris from the oil film. Again no big deal, I use it as part of my maintenence , it gives me a chance to look things over while the hood is off.
I also use a fuel stabilizer so I have no issues with fuel going bad and messing things up. Not sure what type injection system Yamaha uses, but the Merc system works well, it allows a very slow idle for long periods of time with no fouling.