Digger wrote on 12/06/08 at 21:18:35:PerrydaSavage wrote on 11/30/08 at 03:10:19:Be careful of those 90 degree valve stem adaptors ... bought a couple thru a link someone posted up here on the Forums a year ago. Had one installed on the rear of my S40 when I bought it in June and after Riding the Bike for a couple of months, my rear tire went flat due to a leak the the valve stem ... I read somewhere since that those 90 & 45 degree adaptors can sometimes cause the valve stem to chafe thru do to the extra forces caused by the weight of the adaptor with high speed wheel rotation. Dunno if this is factual or not, just somethin' I read ...
I'm pretty sure it's factual. GL1800s came with 90-degree valve stems prior to 2009. Those bikes have had a problem with valve stem leaks. Honda supplies a keeper that is supposed to prevent the 90-degree valve stem from drooping at speed (centripetal force) and weakening the valve stem where it enters the wheel.
Those GL1800 valve stems were junk. I got rid of mine fairly quickly.
Just to clarify a little bit.
The 90 degree ADAPTER is not meant to be left on the tire. Only put in place for airing up.
"This part is only to be used when airing the tires. Never ride with the adapter installed or the valve stem could become damaged, resulting in rapid air loss."
I have a 90 degree stem on my tube. (That Dennis Kirk link on my previous post).
No problems yet, and I have 12,000 miles on it. I don't think they would have a problem, unless you put some huge heavy valve stem cap on it.