To much oil, fouling plugs

[beergut]

This does not really apply to these 2-stroke skis. You have no oil control rings and have rather large ring gaps compared to a 4-stroke so a cylinder pressure leak down test really isn't that helpful. Also adding oil isn't really helpful either on these since there is plenty of residual 2-stroke oil on the rings anyways.

On these engines the best diagnosis for the pistons and cylinders is a simple compression test.

I will say a complete engine pressure test is a great test to determine leaking gaskets and seals to prevent lean conditions.

duh! i totally missed that- didnt even realize he had a 2 stroke- I'm so used to dealing with 4-stroke and diesel. leak down test in a 2 stroke will just confirm blown head gasket or cracked piston / cylinder.

 

[Barcley]

Oil pump is aligned and I'm very doubtful of fuel being to rich. Have to feather the throttle till the motor gets warm. Here is a pic of the pump.

 

[Barcley]

If it is really black wet and nasty coming out of the exhaust that's typical of a leaking needle and seat.

The check valves would be suspect if it was flooding with oil when sitting.

Have you checked the oil pump adjustment?

Wouldn't the check valves leak into the carb and not clear out with plugs pulled? Again the chances of both check valve failing at the same time is slim to none so agree on ruling them out. Its something that will affect both cylinders. Excessive smoke is why I'm leaning towards oil fouling. Plus look at the plugs I posted. 10 minutes and drenched with oil.

 

[JeremyD615]

Well feathering the throttle could be a sign of either a rich or a lean condition. I’d be willing to bet you’re rich with fuel rather than oil.... If you give it just a bit of choke when it’s cold and you’re having to feather the throttle, does it pick up immediately, or does it want to die?

 

[Barcley]

Die. Doesn't bog. Seams very lean till I build up the fuel and warm the engine.

 

[Barcley]

Let's keep in mind it has progressively gotten worse. Use to run great and slowly started fouling plugs and the fuel habits have stayed the same throughout.

 

[JeremyD615]

If it dies, you’re fuel rich and need to go back through the carbs... Did you replace the needles and seats when you did them? Are you positive that they were genuine OEM Mikuni parts? Did you replace the springs when you did the rebuild?

 

[Barcley]

When I say it dies, I mean if I punch the throttle, you can here the rev fall till I let go and it levels back off. I know the difference between the two. It's more lean than anything else. Keep in mind have you ever seen a rich carb or leaking needle foul in 10 minutes to pure black plugs? I also have to use the choke till fuel is built up and even past that till engine warms. I can see where you would think this but promise it's more on the lean side. Low is it 1 turn and high is at 0. Being rich doesn't account for the smoke issue as well.

 

[mikidymac]

I’m just not seeing the oil system being the issue here but I have been wrong before.

If it’s the oil pump leaking, pump check valves, crank seals or rotary seal you would expect to see it flooding with oil when sitting.

The only oil issue I could see is if the pump was pumping too much oil when running but I have never once heard of that happening unless the cable was slack and the arm was wide open.

I have seen plenty of skis foul plugs from too much fuel which is why all of us are still leaning that way.

 

[Barcley]

I agree up until you say the rotary valve. It rotates correct? Meaning if it's not moving the chances of it leaking may be slim while sitting. Keep in mind I clear the cylinders out before I ride so if it was leaking oil while sitting, I'd see it. Dont get me wrong I will totally go through the carb to see what what's going on, but how do you explain the excessive smoke?

 

[JeremyD615]

Even if the rotary valve was leaking, it would be from the shaft seal, not the rotary valve itself, and it would fill the crankcase with oil. The fact that it’s not hydro locking the motor is what’s leading me to believe it’s fuel. Remember, you have some oil in the crankcase at all times anyway. The fuel will be black when it gets to the plugs...

 

[JeremyD615]

Just for reference, here’s a good plug that’s only slightly on the rich side. This plug has about an hour on it and is pretty black already.

 

[Barcley]

Actually that's exactly what my pto plug looks like. Ok I'm open to the fact it may be fuel related. Probably looking for a leaking needle correct? While I have the carb off I can inspect the oil side of things as well and inspect there too. I have a rebuild kit on hand just not sure about needle and spring. Never hurts to rebuild the carb again to be sure. As far as the RV all I need to do is pull the cover to look for oil correct? If the seal is bad it will be behind the cover as well?

 

[mikidymac]

You will always see oil on the rotary valve because that’s where the oil gets injected.

Make sure you only use Genuine Mikuni parts.

 

[Barcley]

When you run a single carb rich enough to foul the plugs, which plug is likely to foul first?

 

[mikidymac]

Hard to say but the front cylinder typically runs a little cooler so should be the front.

 

[Barcley]

Ok thanks. May need help with the rebuild. Thanks for all the help. I've needed to break this ski down for awhile now just didnt want to miss the season you know.

 

[mikidymac]

What are your compression numbers?
Don't jump to an engine rebuild just yet.

 

[Barcley]

148/150. Starting with the carb and inspecting RV side of the motor. Guy who had it before me was an idiot and I've already had to fix a ton of his mistakes. Fuel lines, front to back are done, been thru all the water lines, all the exhaust, all zips into stainless clamps, entire hull has been wet sanded and shined, seat cover. After the carb and inspect RV I've pretty been thru the whole ski until it's time for a rebuild.

 

[FL-Rider]

It sounds like its just running rich to me too. My ultra150 just did that. It would foul the plug after a couple hours run time, then got progressively worse until a new plug lasted only 15 minutes. Turned out to be just a carb issue. Likely its your needle and seat, lever arm bent or binding, spring, or maybe the diaphragm came out of the groove a little during assembly. Since you just rebuilt it, hopefully its just a binding part and you can just re-assemble.

 

[FL-Rider]

One more thought. Since all the fuel line were just done, any chance the return line is kinked or restricted?

 

[Barcley]

It sounds like its just running rich to me too. My ultra150 just did that. It would foul the plug after a couple hours run time, then got progressively worse until a new plug lasted only 15 minutes. Turned out to be just a carb issue. Likely its your needle and seat, lever arm bent or binding, spring, or maybe the diaphragm came out of the groove a little during assembly. Since you just rebuilt it, hopefully its just a binding part and you can just re-assemble.

I actually didn't do the rebuild but totally trust the guy that did. However if he did pop off and was ok maybe he didn't change the needle or maybe someone else changed jetting. I will soon find out. About the kink in the line I will definitely check that as well. Thanks.

 

[R-u-n2it]

duh! i totally missed that- didnt even realize he had a 2 stroke- I'm so used to dealing with 4-stroke and diesel. leak down test in a 2 stroke will just confirm blown head gasket or cracked piston / cylinder.

A leak down test will indicate bad main seals, bad o-ring head seal, anywhere bolt holes go into bottom end, leaking rotary valve cover etc. If it was a carb problem and only 1 carb the plugs should look close to the same unless 1 inner main was leaking. A weak spark from high resistance connection can can cause incomplete combustion when you nail the throttle, have you trimmed the plug wire ends at the plug cap? When it's smoking does the smoke look black or have a blue or white/light gray tint? My plugs look like yours all the time on purpose but probably not for the same reason. To eliminate the oil pump plug the line and premix once to be sure. Not smokey when you remove the seat is it? And if the little plastic check valve that's screwed onto the fuel block that's under the lever leaks the carb will dribble fuel down the throat, use a mirror (so no burnt eyebrows) and look down the carb throat while it idles and see if it's dripping fuel. One that leaks will load up bad when you chop power after a full throttle to high RPM section. If the prior owner fooled around maybe he removed or altered the restriction in the return fuel line at the carb. I've seen skis run funky from the water lines incorrectly routed. Don't give up, you'll figure it out.

 

[Barcley]

I plan on bringing the ski home monday and will keep.posted what I find. I'd like to test the new coil I put on as well and may need some help.

 

[Barcley]

Fuel lines are all new as well as the check valves on and out. Smoke is white. A ton on first fire up. So far I've found the mag cover bolts loose, exhaust was loose (so now there is no smoke in the hull and thought that was the issue and wasnt) missing motor mount bolt, and clog in water line. Lmao I'm sure I'm forgetting a couple things. Plan is to pull carb and check pop off, inspect RV for oil leaks, and leak down test. When you asked about the smoke, is it because white smoke mean fuel and blackish means oil I'm guessing? I've been leaning towards fuel instead of oil do to the symptoms I'm seeing and learning from this forum.