we all have a serious gas issue!

[yamahansolo]

I believe after my experiance and reading tc's. That we have an evaporating issue!
I posted a couple months ago that I got 41 or so mpg on a trip through mountains... andriding around town I get 36 to38. Well I just got back from the tail of the dragon and I got 43.983something.
Plus I am still. A teensy bit rich. I have to pull the carbs off to adjust my number 3 I can't adjust it on the. Bike because of the oil line. Also its shimmed up.the idle screw is 4 turns. Out and I need to bring it all the way backin to half a turn.

Any who if I ride to work everyday for the week milage is down. Could our rubber inside be. Allowng too much evaporation? Also I topped of the tank and parkeda little to far sideways and somespilled out the top while I was eating... maybe we need a replacement spring in there or rubber...??? Any ideas?
Thanks!

[b.walker5]

Ummmm.... all gas has evaporation issues, influenced by heat and altitude, etc. Gas is a mixture of octane boosters, lead substitutes, and various other chemicals that all have different boiling points, which means different evaporation rates. Thats why gas goes stale, some additives boil off (evaporate) before others leaving lower quality sludge behind, and as your fuel system has to be vented it cant be avoided. Trick is to use it before it dies or top up regularly to keep it fresh.

[DGXSER]

We all at some point expereince the freshly topped off tank that spews gas when you let it sit. I believe this comes from the gas getting heated by the motor heat rising up, with the tank plum full, no where for vapors to expand to or the liquid to expand to, so it comes out the top.

As to the rubber replacement. If the seal at the top of your tank looks old and brittle or cracked. You can certainly buy a replacement for it. I put a thread together a while ago on how to rebuild the gas cap and found a radiator cap gasket that works very well. The OEM is still available as well.

[yamahansolo]

Uummmmm I know gas evaporates... and I know when it gets hot itexpands... I just was saying ... it seems to evaporate really fast. Several if my other bikes didn't evaporateas fast.

[81xsproject]

The gas spills out after a fill up, because it has a much greater thermal expansion and contraction that other fluids such as water. I did it last year. Filled up to the brim a mile from work. Parked in the morning and everything was fine. Later on, when day time temp rose, the gas warmed and expanded and over flowed out the lid. Why do you think those plastic red gas cans have that FILL line on them that is so far from the top?

[DGXSER]

That points to the seal or the vent not being proper. If the seal is bad, it will allow the vapor to escape rapidly, and if some PO took the filter out of the vent in the cap, it will let much more vapor out than it should at normal operating pressure.

[natemoen]

That points to the seal or the vent not being proper. If the seal is bad, it will allow the vapor to escape rapidly, and if some PO took the filter out of the vent in the cap, it will let much more vapor out than it should at normal operating pressure.

What filter are you talking about?

[DGXSER]

Nate, there is a filter in the gas cap vent. A fiber material.

[bikerphil]

if I ride to work everyday for the week milage is down. Any ideas?

Very simple explanation, gas thieves. Kidding aside, you ride your bike to work all week and the mileage is less per gal. than if you rode it all day long in one shot. Every time you start the bike cold to go to and from work, it will be using more gas with an engine that is not up to operating temperature for the first few miles. Warmed up engine is getting much better mileage than starting and riding with a cold engine 10+ times. Oh, and the gas might evaporate too.

[fredintoon]

Nate, there is a filter in the gas cap vent. A fiber material.

Hi DGXSER,
make that "there should be a" rather than "there is a".
Most XS11s have had that filter discarded by the dreaded PO when they changed out the cap sealing rubber.

[yamahansolo]

Sounds like I need to investigate for a filter...
I think there is an issue with mine because non if the other bikes I have owned had that much of a difference in gas mileage maybe 1 to 3 MPG but not 6 to 8 like thus one.

[DGXSER]

Interesting Fred, both of mine have had it in there. Thsu I expected it to be the exception and not the rule that it would be AWOL.

[cywelchjr]

I'll say that these things seem a lot more fuel hungry cold than my other bikes I've had, including my other Yamaha. But even riding every day, I find a HUGE difference between riding where it cools off between rides and where it doesn't, so I don't think it's evaporation, I think they just use that much more gas while warming up.

[yamahansolo]

Not trying to argue but in my case I disagree...

Iprimarily ride to work. If I ride every day in a row I get right at 40 mpg. If I skip a day due to rain or something I get 38 mpg and if I skip3 days or. So it drops to 36 mpg. I am startingit the same number of times only diference is how many days idont ride in between.
Also I am naught and I my enrichment on the zrx carbs has to be held in place so I pull it crank it. Wait about 30 seconds and take off... I go easy though till its warmed up.but as soon as I take off the. Lever drops back in...

[cywelchjr]

Well, your point is well taken. That said, I don't have that problem with mine, so I would say you have a leak of some sort somewhere. I can't even see gas evaporating that fast, even if the vent was just about wide open on the cap. Was it you who said that you have to use prime if it's sat for more than a day or two when starting it? That would say that fuel is leaving the carbs at a faster rate than would be normal, as I can have mine sit for a week and still start it without prime, nothing more than putting the choke on.

And the only difference I get in gas mileage is whether it's a bunch of short trips from cold or longer trips with a warmed up engine. Makes literally no difference (at least not measurable) whether it's every day, or if it sits for 2, 3 or 4 days in between rides.

So maybe your including to many others in there in the title, as I for one don't have the issue you do.