Strong smell of partially burned petrol after bike is parked

[Grumpy Goat]

Ever since I got this bike (pre-owned) at about 2900 miles I noticed a strong smell of (I believe, partially) burned petrol in my garage after I return and the garage door is closed. The smell lingers for a few hours before going away, and next day there is no smell. There is no fuel leaking on the ground. The bike runs very well, starts well, there is no gasoline smell when I am riding it (as far as I can tell), and the fuel economy is good, but the smell is like the bike is running rich all through the year - even in the hot months. My other bike does not have this problem at all, and I smell no fuel when that bike is parked in the garage, just a whiff of exhaust as you would expect.

Anyone else notice the same with their bikes?

Aby idea what might be the problem? 

[Heli ATP]

Is your ECU flashed? There was a post some time back of a smell where the ECU had been flashed. Flash was removed and smell went away.

Search Paranoia or normal

[Grumpy Goat]

1 hour ago, Heli ATP said:

Is your ECU flashed? There was a post some time back of a smell where the ECU had been flashed. Flash was removed and smell went away.

Search Paranoia or normal

Bog standard engine ... no flash no nothing.

[KrustyKush]

My son’s 2004 Sportster stinks like this. To ride behind him is to smell the stink. He bought the bike used, so obviously the previous owner dicked with the carburetor to richen the mixture, which is a common thing to do. I feel like they went too far in the rich direction. My son isn’t concerned about it.

Best guess would be previous owner of OP bike did something to cause the bike to run rich. Too rich. 

[Grumpy Goat]

29 minutes ago, KrustyKush said:

My son’s 2004 Sportster stinks like this. To ride behind him is to smell the stink. He bought the bike used, so obviously the previous owner dicked with the carburetor to richen the mixture, which is a common thing to do. I feel like they went too far in the rich direction. My son isn’t concerned about it.

Best guess would be previous owner of OP bike did something to cause the bike to run rich. Too rich. 

Thing is I don’t thing there is a smell while it is running. It’s when it is shut down and in my garage it sort of oozes this gasoline stink. For a while. 
 

The previous owner only had it for 2900 miles or so before trading it and it was in mint condition so hardly something you’d think was tuned. Could have been, I suppose. 

[KrustyKush]

Definitely could have been.  My son's Sportster, an 04 model, had only 4k miles on it when he bought it.  I have smelled this rich smell many times while following a "tuned" bike. You won't notice it while riding because the stink is behind you.  People behind you may notice it, though.  And when you pull into the garage, the stink will linger for awhile from the gas that is left in the pipes.  It really stinks bad when the bike is first started cold and sits there idling for a few minutes.  That is when I notice it the most.  Oddly, my son hardly aware of it.  I had to point it out to him.  He evidently thought the stink is normal.  It is not.

Lots of bikes get dicked with before they even leave the dealer shop.  New pipes, new tune.  Less common for Japanese bikes to get this treatment on a new bike, but it does happen.  Some folks start with the assumption that the factory tune is bad.  With a carb, it is necessary to disassemble the carb to get at the jets, to replace them.  Not so hard on a FI bike, just load in a new map.

Also possible the carb on my son's bike has suffered from all those years of sitting still.  It may simply need a good cleaning.  It is harder to figure sitting still as a similar problem on a FI bike like the Yamaha, which leads me to think it was modified before you got it.

[Grumpy Goat]

2 minutes ago, KrustyKush said:

….  And when you pull into the garage, the stink will linger for awhile from the gas that is left in the pipes.  

 

That makes a lot of sense to me. And yes with a fuel injected bike it is easier to load some sort of different map into the ECU I guess. 
 

I guess I’d have to take it to a dealer to get it reverted?

[Grumpy Goat]

Bike is now at a dealership for the first time since I bought it. Let's see what they find. At the very least I will get a full diagnostics report and have a baseline for this bike. That is one of the things I don't like about buying pre-owned - you don't really have knowledge of everything that was done to the bike is not "visible".

[Boat]

My guess is it has something to do with the tank ventilation (charcoal canister) system...  

[Grumpy Goat]

40 minutes ago, Boat said:

My guess is it has something to do with the tank ventilation (charcoal canister) system...  

Sounds reasonable to me. I guess in such a scenario you’d want to replace the canister. Question would be why would it have gotten fouled in the first place, i.e. what would be the root cause … 🤔

[betoney]

1 hour ago, Boat said:

My guess is it has something to do with the tank ventilation (charcoal canister) system...  

 

43 minutes ago, Grumpy Goat said:

Sounds reasonable to me. I guess in such a scenario you’d want to replace the canister. Question would be why would it have gotten fouled in the first place, i.e. what would be the root cause … 🤔

I believe only California models have the charcoal canister. 

[KrustyKush]

I understand way overfilling the fuel tank, followed perhaps by the bike sitting in sunshine and heating up the fuel which may expand and leach thru the vent tube into the charcoal canister.  That's what I've heard.  Never seen it.  I've got a CA Tracer, with the canister, not a trace of fumes, but I don't really force the fuel to the top of the tank.

 

[KrustyKush]

One Yamaha I had, an 07 Venture, was a not-CA bike and had no canister. A vent hose dumped right out onto the ground under the bike.  On a warm day after the bike sat for a couple of hours in sunshine on a full tank, fuel would drip out onto the pavement, make a good sized puddle that looked for all the world like a major leak.  Stink, too.  Once the tank burned off a gallon or two, the drainage would go away.  

[Grumpy Goat]

16 minutes ago, KrustyKush said:

I understand way overfilling the fuel tank, followed perhaps by the bike sitting in sunshine and heating up the fuel which may expand and leach thru the vent tube into the charcoal canister.  That's what I've heard.  Never seen it.  I've got a CA Tracer, with the canister, not a trace of fumes, but I don't really force the fuel to the top of the tank.

 

I heard of that too but that is not at all the case here. Don’t know if the charcoal canister, if fitted, was damaged previously, but I always only fill to the metal “grate” That you stuck the nozzle through. We’ll see what the mechanics at the dealership say. All I know is that they’re planning to charge me $190 just for the diagnostics and inspection. They had better credit that towards the repair or else they will lose a customer. I know that there is labor involved in diagnosing but even BMW doesn’t charge that much just to diagnose. This is a Yamaha FFS. 

[Boat]

Let us know what they find.  I have had a slight gas smell in mine (CA model) sometimes.  It seems to come from the gas cap area and is never really that strong, but is noticeable...

I just attributed it to normal off gassing ventilation...