Oil smells like gas... By DrRocco (Read 12,271 times)

[DrRocco]

I put the first 100 Km on my scooter and decided to do the first oil change.  A few days ago when I checked the oil, it was way over-full, which I thought was strange.  Today, after draining the oil, I noticed it smells like gas.  The scooter has been running great though.  Starts and runs like a dream.  Any ideas?

[kz1000st]

You might want to pull the fuel line and see if it flows even if the engine is not running. It sounds like either the petcock isn't shutting off or the float needle is sticking. Overflow gas could be getting into the sump. I would put in some Seafoam and run it. I'm not a fan of opening up the carburetor but you may have to. To me Carburetor is a French word that means "Do Not Touch."

[LUKE]

see?...i toldya!....IT'S THE GASKET!!!!
or you must have put the gas in the crank case by mistake....anything is possible, be careful next time.
but i hope it's not something serious.



now you are sitting right above an engine that can explode anytime with a tiny spark...kaboom...LOL


be careful bud! i don't wish bad karma to people., have it checked by professionals.

[LUKE]

seafoam? really?...the scooter is BRAND NEW!hellow!!! kz, you are really disappointing me...
but kz is right on the petcock issue..

[DrRocco]

I pulled the fuel line coming out of the shutoff valve. No immediate leaks. I let it sit like that for about half an hour to see if maybe there was a slow leak. Not even the beginning of a drop formed. The fuel shutoff is good to go.

[jct842]

When new the rings are not seated and have some leakage. As long as the oil is not thinned out or the level does not grow your ok. After 5-600 miles if it is still that way I might be concerned.

[kz1000st]

I agree with JCT. I just didn't want to say, "Ignore it, they all do that." and have a cascade of ARE YOU CRAZY comments. If there's no overflow and the scooter isn't burbling from flooding I'd ignore it.

Spare me Luke. With Yamaha's record for fuel pumps and seals you should be very quiet.

[DrRocco]

Glad to hear that guys. I have absolutely zero mechanical experience, but I was hoping that could be the explanation before I brought it to you. I'll keep an eye on it. Oil is cheap. I'll change it frequently for a while and see if the condition improves.

[clonedrone]

I'll take a stab at this.
Couple things, In Il is the Scoot new or did it sit over a few months of Winter with Gas from last fall or Winter in it?
If the oil is showing Overfull I seriously doubt or no way there is that much Blow By on the new rings to cause a overfull condition.
If so you would have so much Positive Crank Case pressure that you wold be Blowing all kinds of oil out the Breather.
I have found two different Ring packs in these late model Four Smoke Scoots.
a .039 Top (1mm) a .047 second and a .110 three pice Oil ring.
Second a even thinner .031 top, .031 second and a .059 Oil ring.
The Top or compression Ring is of good quality Stainless with a Chrome Face, The Cylinder's now are all Plateau Honed with a very Fine Finish.
A Plateau hone can be visualized like a Pyramid with the Sharp Pointy top Knocked off Flat, The Older Honing process is like a Sharp pointy Pyramid.
The later in break in you had to knock the top off the Pyramid with Much thicker ring packs.
These Modern Cylinder Piston assy, Seal up very well from the get go.

The Bright Side.
i would venture to guess that there has been some fuel sitting in the carb/Tank that has caused the Float and or needle and Seat to stick open causing the Overflow of Gas
in the oil, Hopefully just by running it you have run some fuel thru it and it cleaned itself, If not and you have no tools or skills you may want to try a Ethanol Treatment..
All to most of the Ethanol treatments use Petroleum Distillates as a cleaner so not much difference in what brand.
Ride On!
Clone

[DrRocco]

Clone, this is a brand new scooter. I've only had it a couple weeks. I did a pretty thorough PDI on it. I even had the carb apart and inspected the float assembly to make sure everything was moving freely. When I first started it up, I put about half a tank of garbage 2 year old gas in it. Once I made sure it ran, I topped it off with premium fuel with Sea Foam. I burned about half of that, then topped it off again with the premium/Sea Foam mix. When I initially put oil in it, it was almost to the top of the hashed area on the dipstick. After running it 80 Km or so, I checked the oil again and it had risen to the bottom of the cap, about 1/2" from the fill opening. The oil seemed to have the same viscosity and on a scale of 1-10, I'd say the gas smell in it was about a 4.

[clonedrone]

All good
I think your on it.
I would have recommended dumping the Old Fuel but as stated I think your on it.
Ride On!
Clone

[cyborg]

As a side Q Clone how do they hone these nikasil and ceramic bore coatings?,,,,, diamond hones?,,,,gotta be correct?

[clonedrone]

The Nikasil is the predominant coating for Cylinders these days.
Yes they use a Diamond and or Ceramic Hones on them usually in a Sunnen automatic Honing machine.
The Final Finish can be altered depending on the application ie. A Race application cylinder will get a courser finish for fast break in compared to a
normal Replate a very fine finish, Cant and Don't baby the fine finish or move to Synthetics to early or you may glaze the cylinder and take forever to break it in.
Chris at Millennium seems to do the best consistent replates in my experience.
I'm no fan of iron cylinders or Iron sleeves in Cylinders, they have horrible heat dissipation and Thermal Expansion quality's.
Thus I can set up a Piston clearance much tighter in a Plated cylinder,Superior ring seal, skirt wear and longevity.
The bets place for Iron is the back yard grill, it does not belong in any modern Engine.

[cyborg]

I thought it would be diamond,,, never thought about ceramic hones,,,i know that the nikasil is crazy hard thanks

[Bashan]

There's gas getting in the oil....no doubt and no doubt it will destroy that new scooter engine. You pulled the fuel line off and no leak....fine. Gas can get down in the engine through the vac system predominantly two ways: the diaphragm in the petcock or fuel valve is leaking and pulling gas into the line, second, the air cut valve diaphragm is leaking and pulling gas in. Run the bike a bit, shut it off and pull the vac line at the intake manifold. Check it for gas or if it reeks of gas smell. If it does, that's where it's getting in. Until we find it, change your oil a lot! Like everyday. I'm serious. JMO. Rich