Gasoline smell coming from EBS??
 

Happy New Year esteemed riders,


I have a hose-based external breather on my 07 XL1200L. The stock breather screws have been replaced by banjo fittings and breather bolts from DK Custom. A filter was also included but, screw the epa, I just routed the hose straight to the ground without filter or catch can.


this morning, after a nice long ride, for some reason I stuck my nose near the end of the hose and lo and behold, there was a smell of gasoline coming from there. It's not there when I just start out but I do smell it after riding for a while and the engine is hot.


Does that mean the piston rings need to be replaced?


Thank you for reading.

If you have breather bolts with the little screens, and banjo fittings, are the bolts inside your aircleaner? Could vapor from the TB/manifold just back vent through the banjos and out your hose?

If you are worried about your piston rings, do a compression check on both cylinders.

John

No not the ones with the little screens. Plus the EBS is completely separate from the air cleaner. Here is a prototype of what it looks like right now:

https://cimg2.ibsrv.net/gimg/www.hdf...c18965b9ed.jpg

i've has that happen... no idea why.

While it does look clean and symmetrical there, I would route the hose(s) down to the bottom of the bike where the smell/vapor will not be a bother.

Ok, I can do that. I'll need to educate myself on how to do that first.
So it's not a big red flag to have gas smell outta the breathers?
Yeah, I guess if it's normal operation to have gasoline smell coming out then I'll route it down and be done with it. I am just experimenting right now. If there absolutely should NOT be, then I need to fix the root cause.

I'm having trouble seeing where the hoses are routed. In the photo, it looks like there is a single clear hose going from one banjo to the other.

Cristy

Yes. That single clear hose arcs from one banjo to the other and has a hole at the top where the hot air exits:When I removed the stock breather screws to put in the banjos, I saw that the stock screws each had a small hole where the hot air exits. I measured the stock hole size and then I drilled the hole in my clear hose to be twice the size of the stock hole.

I sort of like what you did.

You should have no gas smell coming out of that hole.

But, it is possible that you are smelling gas from your intake and not the breather tube...they are very close.

If a gas smell is coming from the actual breather hose, you are either too rich and gas is making it's way past the rings in the the bottom end, and then coming out the breathers, or your rings are worn and letting gas past.

If it is running well I would not worry about the rings. If you want to satisfy your curiosity, a leak down test will let you know if there is an issue.

Thank you Kevin!

I can also use the long black hose you provided (in an earlier kit I got) and route it down towards the road. But even then, if I stick my nose at the end of the hose, I can smell the gasoline. The smell is only apparent when the engine has run for a while. Like 20 or so mins.
Is a leak down test the same as the "compression test" that John referred to above?

Opposite operations. Compression test you measure how much pressure is created as the piston comes up to TDC. Leakdown you fill the (piston at TDC) cylinder to a certain pressure, and see how it decreases over time past the rings. IIRC.

Compression test is generally easier to get a baseline compression, roughly 120-150 psi (8-10:1 compression@15 psi or 1 atm)

Not sure what psi you would fill the cylinder to for a leakdown test, at least the above numbers I would think.

John

I don't claim to know a great deal about Sportsters but if the vent system is anything like a Twin Cam you need a hose going to the ground or a catch can. The breather bolt holes on a Twin Cam are below a one way umbrella valve; if you don't have them routed to the intake; a hose that goes to the ground or a catch can all you're going to do is impede venting by filling up the hole with oil. You can't push it back up past the umbrella to return it to the engine; especially since there is pressure venting out while the engine is running and oil doesn't run uphill when the engine is off.

There can be a problem with Sportster, Twin Cams & M8's IF you do mostly short runs, especially in cold weather (less than 30 minutes).

Not that it will significantly impede the air flow...they will vent fine, since the air will push thru the oil...BUT, with lots of short runs the oil will build up, filling the cavities between the umbrella valves and the end of the breather bolts.

With longer runs (30 minutes and more) the oil will not build up, the heat of the engine will vaporize it, pushing it out with the vented oxygen depleted air.

I wouldn't run a rig like that. The Twin Cam breather bolt hole is essentially a blind hole with an entrance at the top for the pressure and oil mist to exit out of. There is no provision for oil left in there to drain back into the engine. I wouldn't bet on engine heat to eliminate the oil trapped in there to the point that some residual form didn't still reside. Heck, I wouldn't even think that's possible if you piped it to the cat converter. There's gonna be something left.

Mind you this is only an opinion and it surely isn't gospel. But if you go all that way to correct a poor design, why not do it right? It's kinda like putting your hand over your mouth when you feel yourself throwing up; it don't do much good;)

I think I've seen breathers that are already connected with metal pipe (horseshoe breather?) installed above the carb. I'm not sure how if it is above the carb and you had a hose from the outpipe down to the ground, the oil would migrate upward any more than the PO's system.

John

Like this one?
https://cimg5.ibsrv.net/gimg/www.hdf...5d3734f6a2.jpg

There are a lot of people running Drag Specialties horse shoe breathers on Sportsters. Me for one. I'm sure they were tested before being put on the market. Hammer Performance sells them. and those boys know a thing or 2 about Sportsters.

The difference between what you have and what's pictured above is that there's a place for the oil to go.

You're right, there is a way down for the oil, wasn't sure how they outpiped.

John

Thank you for all the replies. Really appreciate learning from you guys.

Yes, right off the bat I did have concerns about clogging... which is why I used a clear tube, so I can monitor what's coming out of the breather bolts.

Instead of just a hole at the top of the clear tube, I could put a filter. I ordered and received a tank lift kit from DK Custom yesterday. By raising the tank 2" I should be able to fit a filter in between the tank and the velocity stack. But then that kinda ruins the clean streamlined look I was hoping to accomplish.

Or, I could just route everything downwards and be done with it. That way, my gasoline smell issue goes away for sure. And I get to keep saying screw the epa :D

I know that none of the above addresses the possibility of bad rings; which was the reason for this thread in the first place. But I realize that even if I found out that the rings were letting gas through, I am not prepared to do anything about it right now. The bike runs really well and I am reluctant to change that for now. Later this year, I hope to save enough for a 1275, at which point the "bad ring" issue will then fix itself.