Thanks to all for the replies. Nippybit, I will probably try that next, or just vent to atmosphere. I had that same setup on my previous bike on a Clark 4.2 gallon tank. Bartron's "code Orange" thread describes the method I followed for the partial "canirestomy"and so I figured others have done the same. He recommends what you did, OR the in-line valve as I did. Either method accomplishes the same as the valve is supposed to perform the same function, whether is mounted to the gas cap or in-line. BTW, the expansion has been due to just normal summer riding as I have not parked the bike in the sun for any extended periods. A friend who is a pretty good mechanic and does all the work on his own bikes ( but does not have a KTM) thinks that the amount of pressure that builds up is not sufficient to have a detrimental effect. So far, the bike runs great, but my concern is long term.