Gas boiling while riding bike? New gas cap + paint, too

[UG0TB4NN3D]

Well that just doesn't sound safe at all! I was riding my bike yesterday and pulled over at a gas station and when I came back out, I heard my bike blowing out gas fumes from the new cap (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=250659131700). The cap has a little vented hole so it doesn't build up pressure, but when I pulled the cap and looked, the gas was boiling! My gas tank is also black, but boiling gas is a little scary. Is this normal for a black bike? And should my cap always be blowing gas fumes out?

[katanarider]

Bro...that sounds scary.
Are you sure your gas tank is not sitting on top of your engine /valve cover or your bike is not over heating?
Something is definitly wrong here. I'm not sure what the boiling temperature for gasoline is but I'll Google it rite quick. Hold on.

O.K, from what I've gathered it does not have a sigle boiling point because its a compond. The different additives boil at different temperatures and atmospheric pressure also plays a role.
Did you have some weird additives in your tank that day? If so, flush it out immediatly. What was the temperature that day? Has it only did it once?
I don't know man !

[STULER]

Just because your tank is black doesnt mean ur gas is going to boil. You literally mean BOILING. and yea there should be venting to prevent a lot of pressure

[hardlydangerous]

Its actually normal, scary but normal. Now you know what VAPOR LOCK looks like.
that is basically what it is doing only we dont have issues with vapor lock on a vented system.

I had that happen once after a hard fast ride on my CX650 and it scared the **** outta me. My Kat did it once to

I popped the seat off and ripped the plug for the sending unit apart thinking I had a short in the unit or something, but it continued to bubble away.
So I quickly undid the 2 bolts and took the tank off. Almost instantly it stopped while off the bike and on the grass 50' away (just incase it went up in flames lol)
The heat off the engine was actually the cause of the bubbling fuel. Later I looked it up and its not actually BOILING its bubbling and can be caused by a few things, most notable is ventalation. I have found it more comon when people run tank bags that restrict the tanks ability to breath. When fuel is compressed it can foam and bubble as it builds up heat.
Winter gas and its additives or lack of is said to be a major contributor to the problem.

the easy solution is to cover the bottom of the tank with a stick on heatshield Mat like you find on many newer SS bikes and snowmobiles ATV etc
I have this on my Kat

http://www.heatshieldproducts.com/productdetail/fuel-tank-air-box-and-faring-heat-shields/powersports-heatshield-mat/97/35

[STULER]

Its actually normal, scary but normal. Now you know what VAPOR LOCK looks like.
that is basically what it is doing only we dont have issues with vapor lock on a vented system.

I had that happen once after a hard fast ride on my CX650 and it scared the **** outta me. My Kat did it once to

I popped the seat off and ripped the plug for the sending unit apart thinking I had a short in the unit or something, but it continued to bubble away.
So I quickly undid the 2 bolts and took the tank off. Almost instantly it stopped while off the bike and on the grass 50' away (just incase it went up in flames lol)
The heat off the engine was actually the cause of the bubbling fuel. Later I looked it up and its not actually BOILING its bubbling and can be caused by a few things, most notable is ventalation. I have found it more comon when people run tank bags that restrict the tanks ability to breath. When fuel is compressed it can foam and bubble as it builds up heat.
Winter gas and its additives or lack of is said to be a major contributor to the problem.

the easy solution is to cover the bottom of the tank with a stick on heatshield Mat like you find on many newer SS bikes and snowmobiles ATV etc
I have this on my Kat

http://www.heatshieldproducts.com/pr...ield-mat/97/35

Thats y I asked if it was BOILING. Cause pressure can cause liquid to boil. however, if your bike vapor locks, it shouldnt have been running in the first place.

http://en.wikipedia.org/wiki/Vapor_lock

[hardlydangerous]

Its not actually vapor lock...I was pointing out thats what vapor lock looks like. if this bubblinf fuel were to happen in say a fuel rail, then your vapor pressure could be higher then the fuel pressure and you have vapor lock.

Ive seen the newer ST1300 do this and the tanks are still fairly cool to the touch on the outside, NOT boiling hot. so the fuel inside is not actually BOILING it sure sounds like it though. Its bubbling due to the heat vaporising the fuel on the bottom of the tank.

[Kreylyn]

Its bubbling due to the heat vaporising the fuel on the bottom of the tank.

I thought that was the basics of boiling...

The lower point it could boil at is just over 100 degrees f. That would be pretty low temp boil happening in the right circumstances.


Krey

[katanarider]

So is it dangerous? I mean will it explode or catch fire? Sorry if thats dumb.
What should the rider do if he encounters this situation. I'm thinking RUN ... but then my bike, ...so, pour cold fluid in the tank pronto?

[manowar1313]

So is it dangerous? I mean will it explode or catch fire? Sorry if thats dumb.
What should the rider do if he encounters this situation. I'm thinking RUN ... but then my bike, ...so, pour cold fluid in the tank pronto?

I know I've had vapor lock before going into the mountains. From my understanding there is minimal risk, minimal meaning it shouldn't explode unless IDK you're working over a campfire or something. Just open your tank and let it vent for a few minutes.

Fun physics facts: The boiling point of gas is only 173 degrees F. However with pressure it will boil below that.

[chrisimz]

Sounds scary maybe I should think another color before I paint my tank

[cintidude04]

The color you paint your tank wont affect it much. Probably more to do with engine heat than heat from the sun.

[UG0TB4NN3D]

I went ahead and picked up some heat shielding tape from AutoZone, I'll pull the tank off and apply it to the whole underside tonight and see how that does.

Thanks guys.

One more thing, should the tank leak gas if the bike is tipped over? I was testing out my frame sliders and the tank was leaking gas from the cap area.

[manowar1313]

If the tank is full it will happen. Unless you are planning on laying it over a lot I wouldn't worry about it.

[hardlydangerous]

yes fuel will spill out the vented cap

its not something you need to worry about. as I said its common and everythin g from riding mowers to ATV's to motorcycles. Ive never heard of one exploding. Ever
color has nothing to do with it.