davehrn wrote:
...CARB PUKING: the gas boils in the float bowl, our carb sits between the cylinders and get hot.. gas boils at about 150F degrees lower temps at higher altitudes and lower temps with higher ethanol levels (as is used in winter to prevent fuel line freeze up in cars)... doesn't take us much to get the float bowl hot enough to boil gas..

That's interesting Dave. I have always had a carb puking problem but today was horrible - worst puking problem that I have ever had; according to your reply here, I may know why. I added an ounce of Sea Foam per gallon to my tank yesterday... so that was five ounces... and that stuff smelled like pure ethanol.

Anyway, today, for the first time my motorcycle really flooded and I could hear the gas fizzing out and looked down to be able to see it as well. Never had that happen so severe as that.

Hummm.....

Sounds like they have already started the crappy winter gas mine is acting funny too nto running as good as it did for ages.

Mine has only done it when I had SVS and the cylinders were clooged with carbon. Maybe it made it run hot then, who knows but since they fixed it, It has not done it. I do try to use the shut the fuel off before shutting down theory though, Just makes sense. I think we need a fan. It is dangerous I'd say, I had quite a leak on one trip. You'd think it would cause a recall. MC

You know I think the Carb Puking happens but I do not think that is what is going on with my baby. If that was the problem wouldnt it have happened when it was 100 plus degrees when I was riding it during the hottest part of the summer instead of in the upper 70s like it is now? This is the only time I have ever had this problem and I tend to believe Curt that it could be in the crappy gas. I got gas just up the road from my house and I usually get it a different place that has the 100 percent gas. The place I got it has the 10 percent ethanol. I put a few ounces of Seafoam in the tank and if it dont clear it up I will take the carb apart and check the float like you recommend. Dont get me wrong I am not saying that Carb Puking is not what is happenning. I just think it has to be in the gas because it never did this before.

Gas can certainly be a factor .... winter gas has additives which allows the gas to vaporize easier ... bummer for the folks in hot locations.

I don't know how 'regionalized' the gas is.

Doc

Don't ask me why I had to learn so much about this subject, I'm not allowed to say why (legal stuff) well I can say I did have a fire.. and no one was hurt.. and the bike suffered little damage.. but really nothing more.. and yes it was filed with the NTSB (I encourage everyone to file carb puking with the NTSB ) - mine did it at 1 week old for the first time (pre-modifications - at a higher altitude) ... and continues to this day from time to time... Mine is not a frequent offender... happens maybe once a year... and does not seem very dependent on the ambient air temp did it from low 50's to high 90's.

other bikes have this problem... it's just their overflows are routed to the ground... a problem I rectified with a small length of fuel line... but ours just dumps it on your right foot and pipes... so it gets your attention right away.. keep in mind that when ours is overflowing out the overflow.. it is also pushing up through the jets... which causes the engine to flood but this amount will not be noticed most of the time..

I like the thought of the fuel line running between the jugs being a contributing factor.. it if nothing else will contribute to raising the temp of the fuel... Doc, I see you're running baron's air kit... I'd be interested to know, if the smaller air box increases air flow around the carb and fuel line? same thing with moving / eliminating the fuel pump?? I believe it can still happen with those mods if other factors are in play..

contributing factors seem to be the cause... not one main issue.. it's a combo... lean running (makes the engine hot)... engine off (fuel sitting in bowl and line).. winter gas (lower boiling point)... outside temp? not gonna do it if it's real cold... air flow around carb (when moving vs when sitting)... smaller air box / fuel pump present? higher altitudes lower boiling point of gas... improperly set float bowl... having a fuel pump.. having a float bowl heater? does that contribute?.. makes sense to me... if it does in a small way...

winter gas: Winter gasoline blends are phased in as the weather gets cooler. September 15th is the date of the first increase in RVP (reid vapor pressure), and in some areas the allowed RVP eventually increases to 15 psi. info found here:
http://www.theoildrum.com/story/2006/9/13/234043/431

I was shocked to learn that the boiling point of gas can be as low as 100 degrees F ... depending on altitude and additives... racers have known this for years and even thinking conservatively I know my engine gets over 200 degree's between the jugs..

man see what happens when you get me started!!!

Anybody remember the old "ice cans" we used to put on our drag cars...back in the day? I used to run a Hemi in a cuda at the track that liked to vapor lock,..on those hot summer days, 90 plus... I had a big coffee can with the plastic lid on it, and two little holes in the bottom of it,(drain puposes)... the fuel line going in one side...coiling around in it about 5 times, then coming out and to the carb. Worked great. I always had a cooler with ice so when it came time to get in lane, ...take the lid off the can, throw in a couple handfuls of ice and go. Big ole' coffee can probably wouldnt look to cool on the side of the Roadie though.