1980 gs1000e fitting a front tubeless .....

[Joe Nardy]

The metal valve stems that fit GS wheels are skinnier than the metal valve stems you'll find in car shops.

Basically, they're the same diameter as the threads on the valve cap all the way down. Car valve stems are fatter at the base because the hole in the car wheel is bigger (the hole in the GS wheel is about 8mm, or 5/16". Sometimes you'll see this shown as .30" too.).

Most metric motorcycle shops keep some of these around. It's a good idea to change them if the bike has been sitting an unknown time.

FWIW, I have always used car valve stems. They are much cheaper as well as easier to find. It's no big deal, just need to enlarge the hole in the wheel.

Not that I know of -- I live in the motorsports capital of the world and couldn't find anything locally or even through McMaster-Carr. I ended up ordering the counterbore and pilot from an aviation supplier.

If your rim is flat on the bottom like the one in the photo, you don't really need it.

If you have a curved rim, you can use a burr or stone in a die grinder or Dremel tool to shape a flat place for the tire valve seat. This takes some skill, time, and a lot of grinding stones.

The Dremel reinforced cut-off wheels make short work of cutting a flat spot for the valve stem rubber, much more efficient than the stones. Definitely not as nice as Brian's countersink tool but it will get the job done. Be sure to wear eye protection.


Thanks,
Joe