Why on earth are we talking about a Honda part here on the Yamaha TDUB Club?
It’s more about the “theory” of the parts vs the part itself. But, let’s start with the part itself before we get into the theory. It’s technical name is the
Honda CAP, VALVE 42714-KA3-710. But it’s not a “cap” as most of us know as a “valve stem cap” for the tube of our motorcycle wheels.
Honda makes a very specific rubber grommet that goes around the valve stem between the valve cap and the rim face. In the illustration below, it is labeled as “Valve Set Rubber.”
Did You Start Scratching Your Head?
Yes, we (all Non-Honda owners) have metal nuts (outside the rim) on our valve stems. It’s something that only Honda uses on their MX / dualsport bikes.
During my time hanging out at Gustin Motorsports, Graham Gustin simply made a “work around” to do the same thing and does this on every MX / dualsport wheel going out the of the shop. Run the nut up to the valve cap.
WHY DO THEY USE / DO THIS?
The “Honda theory” is, if your tire slips or spins on the rim, you do not want to rip the valve stem out of the tube if it spins as well. Granted, TW200’s are not powerhouses enough to be spinning tires on rims! So this item / topic is just for general knowledge and or if you have another moto in your stable.
But the fact that Honda has this very specific item on their wheels is quite interesting.
I asked Graham of Gustin Motorsports why doesn’t he just include the Honda part on every wheel and he stated that he would have to keep a ton in stock and add the price to every tube change.
Plus, he said that it is easier to see if the valve stem has kicked over or slipped without the black colored Honda piece sitting next to a black valve cap, all against the typical black colored rims that are so popular these days.
So, he simply chucks the valve stem nut up against the valve cap to allow the movement, much like the Honda rubber grommet does.
To Further Investigate
I placed a phone call to JCR Speed Shop of San Clemente, California to ask about the little rubber “dohicky” Honda’s 42714-KA3-710 Cap, Valve. Why did I call this shop? Simple! Johnny Campbell – BAJA LEGAND – TEAM HONDA! Johnny Campbell has a record 11 SCORE Baja 1000 titles and an incredible 17 Baja 1000 wins IN A ROW! These are just two of a long list of impressive statistics that solidify Johnny Campbell’s rightful place in the Off-Road Motorsports Hall of Fame. In 2001, Johnny finished 8th overall (1st privateer) at the Paris-to-Dakar Rally. He has returned to Dakar as a navigator for Robby Gordon. The duo won three stages at Dakar in 2012.
Johnny Campbell has played a significant role in the development of Honda’s XR600, XR650, CRF450X and CRF450RX. He also worked for HGA (Honda Japan) in the development of the CRF450 Rally machine.
THATS WHY!
In talking with JCR-Honda, they confirmed and agreed about the technical aspects of the Honda CAP, VALVE 42714-KA3-710 being designed to allow valve stem movement without ripping from the tube. But too, they stated they are using tire mousse for Baja – desert – rally competitions, thus, no tubes, so no need for the Honda-spec rubber grommet. But JCR did confirm that the Honda CAP, VALVE 42714-KA3-710 was in fact on the 2021 Honda XR450 Rally sitting in their shop.
More Reading
ThumperTalk Valve Stem Rubber Thingee discussion: https://thumpertalk.com/forums/topic/1235761-valve-stem-nuts/page/2/?tab=comments#comment-13833609
Want to use the actual Honda part? Order here.
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