Did a long ride this past weekend. Twice right after fueling I pulled out on to the interstate and a mile or two up the road the motor died from lack of fuel. First time the engine was very hot from running hard so I thought maybe vapor lock. Second time though it was stone cold.

I'm running a Frisco Sporty tank, raked enough I can not fill it all the way up but I try real hard to. I run 2 -1/4" petcocks without reserve feeding a new Pingel 2 in to 1 filter, carb and fuel lines are also new and good, no issues with it except these two times. Rode 1,200 miles in two days and never missed a lick.

I'm thinking that the vent in the cap got covered as I accelerated and starved the motor. I paid attention to how the vent hole was from then on and all seemed well but not sure I nailed it. Any one else have something like this happen?

Road hard for 500 miles or so, filled up with bike hot, pulled out and not 25 yards down the road she choked and died. Checked the usual suspects and found nothing. Pulled the lid off and a good blast of pressure along with a fine mist came out the top. Put lid back on.... Away we went. 5k mikes later It has never happen again.

Not quite sure how that would happen as you can't fill it up past the hole. How would the gas plug up the vent when it's lower in the tank than the cap. To get a vacuum lock in the takes a bit of time so it would have to 'plug' the hole in the cap for a while. Wicking up to the cap vent?

Junk in tank. Refueling mixes it up>

Doc

Hmmm ... based on hammersly's comments ... gas is vaporizing when motor is hot and then condensing out in the tank vent?

Don't know why it would do that when the motor is cold.

Doc

Cold motor with same problem does sound odd but there are far more people here smarter than I... Interesting to follow this to see where it goes.

I have no vent except in the cap. Trust me I can fill it to the lip of the opening and when you accelerate the fuel comes straight on back and up and over the lip (remember the tank is on a rake). I know this since I didn't get the cap all the way on once and spewed fuel all over the tank, motor and my crotch! I was waiting for it to ignite!

The cap has a small hole in the bottom of the center of it and when you twist it on it ends up either pointing forward or rearward. My specualtion is I had it pointing to the rear and it got covered as I accelerated.

I understand but a momentary blockage of the vent would not not cause a tank vent problem. But from what you explained to me I'll agree with you .... the vent must be plugging with gas somehow. Any chance of taking the cap apart and seeing how it plugging up.

I guess a simple solution is to make sure the hole is pointing forward.

Doc