Oil leak?

[OGCollard]

Hey guys first time poster. I have a suspicion you guys,are gonna be as helpful as my xj forum for my jeep cherokee. Which is super helpful. So i just bough a 1990 yamaha 25 hp 2 stroke tiller motor. No electric start. There is some oil that appears on prop after running it. Have attached a pic. Guy i bought from said the shop told him it was exhaust oil buildup. Is this possible? The model is e25f

[OGCollard]

Also, not to be a pest, but what fuel oil ratio do i use with that engine? I have no owners manual

[ausnoelm]

Pretty normal, 50:1 oil.

[boscoe99]

Since oil is being burned in a two stroke engine, and since the exhaust gases in that model flow through the lower unit and out via the propeller hub, it is normal for oil to be on and around the propeller.

If this is a premix model motor, more than likely the gasoline to oil ratio is 100/1. If oil is mixed at a higher ratio there will be a greater amount of unburned oil coming from the exhaust. Spark plugs may foul more frequently.

[bajakeith]

If you mix the oil with the gas yourself

50-1 is the mix and always use tcw3 oil

[boscoe99]

Yamaha sez the mix is 100:1.

Others will say the mix is 50:1.

Maybe some will say the mix should be 25:1.

Believe who you will.

One thing about the inner web is that whatever answer you want, you can find someone that will agree with you. Of course it also means that you will find many that don't agree as well. Side with those that agree with you and life may be good. At least it will be harmonious.

[rodbolt17]

quite a few tiny mite Yamaha motors call for 100/1.
will work great IF and ONLY IF you CONTINUE to READ the manual.
RTFM.
again
RTFM.
the manual ALSO states that if the motor is going to be long term stored,over 30 days, it must be properly "winterized" to protect the shiny nice machined steel parts.

also at 100/1 there is no margin for cooling system degradation,not failure not so good as it should be.

it also allows no margin for fuel system degradation.

its why OMC sent out a bulliten recommending all the OMC tiny mites with 100/1 stickers have the sticker removed and run on 50/1.

[99yam40]

Hey guys first time poster. I have a suspicion you guys,are gonna be as helpful as my xj forum for my jeep cherokee. Which is super helpful. So i just bough a 1990 yamaha 25 hp 2 stroke tiller motor. No electric start. There is some oil that appears on prop after running it. Have attached a pic. Guy i bought from said the shop told him it was exhaust oil buildup. Is this possible? The model is e25f

Looks like someone was decarbonizing the motor with all that black coming out.
Or there is something causing all of the cylinders from burning the fuel properly.
check fuel pump for leaking diaphragm and check/change the plugs plugs

[OGCollard]

Thanks for the input guys! So that would not be considered excessive on that prop except maybe previous owner mixed it to rich? Still running his gas....

[OGCollard]

Thanks for the input on checking plugs. I will certainly do that as well

[99yam40]

when I decarboned my C40 it ran stuff out the prop area like that until the pistons, combustion chambers, and exhaust tuner was cleaned up.


I also had some black unburned fuel/oil dripping out until I replaced the main jets as someone had drilled out the old ones and was running too much fuel into the cylinders at high RPMS causing a miss

[KlinkSanford]

I've seen that on my engines when I ran them at idle/*****ing speed and no high speed run home. I was told you need to run them wide open for 5 minutes coming home, though I only run them 10% below WOT.

[boscoe99]

In addition to the good advice offered above, there are some oils that burn cleaner than others. Yamalube is considered by many to burn on the dirty side. Other brands of semi-synthetic or 100 % synthetic oils may result is less residual oil coming from the exhaust and getting onto the propeller.

Perhaps the bright shiney stainless propeller makes the issue seem worse than it is. The black painted part of the motor does not look so bad.

If you had an airplane with a radial engine you might be concerned every time you went to fly and found oil dripping out of the motor. There will normally be puddles of it on the ground. Nature of the beast. Same with a carbureted two stroke outboard motor.

[rodbolt17]

radials,pancake pushrod 4&6 cyl motors.
they don't leak unless they are running .
nothing like the sound of a pratt&whitney radial on start up.
better than ***.