I went on a 50 mile ride yesterday and I had a buddy ride the wife's Hawkeye. About 4 miles in of riding down a paved road at about 35-38 mph, a large amount of white smoke boils out of the tailpipe of the hawk and it dies. I thought, oh dear God it blew up! It also smelled very acrid, like plastic does when it it melting.

THe engine would turn over but it wouldnot run. We checked for spark and it was firing, but it wouldnot run. We loosend the gas cap and it had a pressure build up or vacuum in the tank as we would hear a rush of air. Put the cap back on and it fired right up with no white smoke and no more acrid smell! What could the white smoke have been from?

Ran great through the trails and mud, very torquey fun bike, can crawl better than most as it is very low geared. My buddy weighs 270 and he loved the bike. (I like the clutch setup on the Hawk better than my Sportsman.)

Anyway, it died a couple more times but always on long stretches of high speed running never on the trails

We'd loosen the cap to release the pressure or vacuum and we'd have to choke it to get it to start, but then it'd run fine.

On the last stretch of highway headed back we loosened the gas cap a lot and it never died.

This does sound like a pinched or clogged gas vent line right. There is no way we should have a pressure difference in the tank if it is vented to atmosphere.

 

sounds like you answered your own question there. its building pressure and its not surpposed too.

 

the vent tube for the gas tank must be pinched somewhere check where it is secured to the frame or around your handle bar area. keep us updated

 

Anyone have any ideas on the white smoke and the acrid smell?

 

It must have something to do with fuel starvation while being run at wide open throttle.