Oil smell from pipes, gasoline smell in crankcase

[chokeslam512]

Well, there you have it. After my bike warms up during my 1.5 mile commute, I smell the oil burning smell. It wasn't that bad at the end of fall but yesterday it was a bit more noticeable. I popped the oil fill cap and took a whiff and it smelled a bit like gasoline.

Any Ideas out there? It is a 2008.

It is under warranty so I think I'll be okay but I'm just curious now before I take it in to the shop.

 

[Shamus McFeeley]

If you think that there is fuel in your oil, you could drain some of the oil out into a glass or plastic jar and see for sure. Fuel (gasoline) is lighter than motor oil so it should float on the top. That depends on how much fuel is getting into your oil in the first place, if any at all. The crankcase usually has that strong hydrocarbon smell to it, but without smelling what you're talking about it's hard to be sure. If your bike is still under warranty, then it can't hurt to take it in while you won't be the one to have to pay.

 

[RJ2112]

Well, there you have it. After my bike warms up during my 1.5 mile commute, I smell the oil burning smell. It wasn't that bad at the end of fall but yesterday it was a bit more noticeable. I popped the oil fill cap and took a whiff and it smelled a bit like gasoline.

Any Ideas out there? It is a 2008.

It is under warranty so I think I'll be okay but I'm just curious now before I take it in to the shop.

If you are getting fuel in the oil, and oil in the exhaust, it's a limited number of things that can cause that. Are you in the habit of romping hard on the gas before the bike is all the way warmed up? Blipping the throttle while the motor is cold?

The rings and cylinder walls must have a good seal to prevent 'blow by'. When the components are cold, they are not the same size as when they are all the way warmed up. When the motor is cold, the FI will program in extra fuel to keep the motor running. It has to work harder due to the thick oil, etc.

Very easy to have a situation where you have a rich mix, and a strong right wrist dumping fuel into your oil.

A compression check would tell the tale.... if you have good compression then you haven't done any damage yet.

 

[Motogiro]

If you think that there is fuel in your oil, you could drain some of the oil out into a glass or plastic jar and see for sure. Fuel (gasoline) is lighter than motor oil so it should float on the top. That depends on how much fuel is getting into your oil in the first place, if any at all. The crankcase usually has that strong hydrocarbon smell to it, but without smelling what you're talking about it's hard to be sure. If your bike is still under warranty, then it can't hurt to take it in while you won't be the one to have to pay.

Yeah but......if the gas is floating on top of the oil, and you drain oil from the oil plug, won't you get oil with no gas because the gas is floating on top?
I totally agree about the hydrocarbon smell!

 

[chokeslam512]

If you are getting fuel in the oil, and oil in the exhaust, it's a limited number of things that can cause that. Are you in the habit of romping hard on the gas before the bike is all the way warmed up? Blipping the throttle while the motor is cold?

The rings and cylinder walls must have a good seal to prevent 'blow by'. When the components are cold, they are not the same size as when they are all the way warmed up. When the motor is cold, the FI will program in extra fuel to keep the motor running. It has to work harder due to the thick oil, etc.

Very easy to have a situation where you have a rich mix, and a strong right wrist dumping fuel into your oil.

A compression check would tell the tale.... if you have good compression then you haven't done any damage yet.

Good info here. I do not give it any throttle while it is still cold (<130*F)... at least no anymore. I remember reading on here that that was bad and haven't done it for a while. Maybe I am imagining the smell from the crankcase. I am riding it to the shop today so I will get a tech to look at and smell it. I will keep everyone up to date when I find out.

I will give it a chance to warm up to 165 or so before I leave and see if it persists.

 

[RJ2112]

Very high RPM operation will also cause more blow by than more sedate engine/piston speeds... if you spend a lot of time above 10K, that would contribute as well.

If you can smell hydrocarbons in the exhaust, that could also be the richer mixture due to the engine warm up..... if you can only smell that when the bike has been running for less than 5 minutes or so, I wouldn't be concerned. The cat has to get hot enough, and the engine warmed all the way up before the cat can burn off the excess. The cat only gets hot from combustion gasses... takes a bit to get there.

As the other guys said, some gas smell in the oil is normal..... that's why oil turns black, after all. It's all due to the combustion gasses that get blown past the rings into the oil. The rings have to have that gap in them so they can expand and contract with heat. The three rings' gaps are supposed to be staggered to limit the blow by (and most likely are). The gaps get much smaller as the rings reach normal operating temperature.

The lowest ring is not there to aid compression..... it's there to ensure a uniform layer of oil on the cylinder wall to provide the surface for the rings to seal against. Similar to the way windshield wipers work far better on a wet surface compared to a dry windshield..... When the gaps are wider, more oil gets splooged into the combustion area.

 

[Shamus McFeeley]

Yeah but......if the gas is floating on top of the oil, and you drain oil from the oil plug, won't you get oil with no gas because the gas is floating on top?
I totally agree about the hydrocarbon smell!

It would really depend on how much fuel was mixing with oil. A better way might be to take a sample with some plastic tubing through the oil check hole or the fill hole. You could always try to take a hot sample after the 1.5 mile commute where the smell seems to be the strongest. That might net a more accurate result.

I agree with RJ2112. Hard revving a cold engine is never a good idea. You're depending on your oils film strength to take the brunt of friction. Even a top shelf oil is going to offer only so much protection.

 

[s13browe]

It could be your short commute sometimes when an engine doesn't run hot long enough and gets cut off without reaching operating temps for a decent time. the engine can build up sludge in the engine sludge tends to have a bad smell and may be what you are experiencing. do you ever take it out for longer trips or mostly under 30 min. of driving?