Valve Stem Issues?

[pugbuddy]

I took off down the freeway for lunch at my favorite hole-in-the-wall and had no issues on the trip. Unfortunately, when I came out to go back to work, my back tire was flat as a pancake!

From my cursory inspection, it appears the valve stem--already replaced once--is the culprit and I'll have to have it replaced. Thankfully, it did not happen, again, at high speed on the highway as that was quite dangerous and frightening.

What I want to know is, is there some way that I'm riding that puts more pressure on the stem? High speeds? Something else? I can't think of anything but it seems odd that the base of the stem on my back tire has broken twice now! Any thoughts on why this would happen again?

[jasondavis48108]

Do you have the stems that are L shaped or do you have the stems which are straight? If you have the L shaped stems I might try replacing them with the straight ones.

[pugbuddy]

L shaped. But the stem is metal. The rubber at the base is what seems to be the issue.

[jasondavis48108]

yeah but I was thinking that the L shaped stem may be getting snagged on something and when spinning its probably putting pressure on the rubber base in a way that a straight one would not. Just a guess though really.

[techoi]

If it has now happened twice on the same wheel, maybe there is something with the rim - a burr or sharp spot...seems odd for sure.

[Dean F]

...maybe there is something with the rim - a burr or sharp spot...seems odd for sure.

Same thing happemed to me when I only had about 200 miles on the scoot and they did indeed find a burr in the hole for the valve. 7000 miles now, a second Maxxis rear tire, and no problems.

[rajron]

I had my front stem fail as well, but, it didn’t fail until well over 10K miles – looking at the stem I could see the rubber deteriorating and come to believe it was just age. I replaced both stems with the right angle ones like OEM because they make it much easier to fill the tire, my new stems are not brass like the OEM they are some silver material, actually they are the stems used on Honda Goldwing MC’s. I thought it was common practice to replace the stem when changing out a tire, in my case I got well over 12K on the front tire, so the stem was never changed until it failed. Now days I take a glance every once in while to see how they are holding up.

[rondothemidget]

Had a similar experience. I take my tires to a Honda dealership. They said, optimally, you should replace the stem each time you replace the tire. However, if it looks good after inspection, they keep the old one.

[pugbuddy]

I'm over 14k on my Buddy. Tulsa Scooters replaced the valve stem with a Honda Goldwing stem for cost ($15)! Awesome service--they even picked up the Buddy and took it to their shop so I didn't have to call a tow truck. I expect I will just need to check the stems closer to make sure they don't wear out.

[jijifer]

I'm resurrecting this thread wondering if this is happening again. It happened twice on a St. Tropez here in San Diego in a matter of 2 weeks. My friend Wayne has had 3 in 4 weeks on a Black Jack. I'm pretty it happened to a Pamplona in the Fall but that rider parked her scooter and bought a Vespa after that.

So the thing in common (though different here) is all the ones failing around here are scooters with the painted rims. Might the paint not be allowing for a good suction or something?

Yesterday, was the 3rd blow out on the Blackjack after many assurances the shop resolved the issue. There was a pop and the tire went flat about as fast as I could turn my head in the direction of the sound. We found the stem in the road and it look like it was TORN off. Not that it just popped so torn.

This lends credence to the idea there's something rough on the rim but FLIP! I don't think my friend will ever trust the back tire will be right after so many damn failed stems!!

[jasondavis48108]

thats crazy! I'd suspect as you do that there is something wrong with the rim and not necessarily the stem although if they are getting the same kind of stem from the same suplier it could be a design flaw. Still, very scary, I'm suprised they got back on the scooter after the second stem fail. I'd try a straight stem from a different manufacturer and I'd check the rim with a magnifying glass to make sure the stems not catching on any small metal barbs or anything. Sorry to here about this issue.

[KABarash]

Just a thought here, These are the 90* stems, correct?

Think about the procedure of checking the tire pressure and the subsquent adding air.
Akward as it seems, use both hands, one supporting the valve stem from behind.
I'm thinking there's tearing caused when pushing on the stem at the rim's edge, that is the most vunerable part of the rubber part of the stem, where it is the smallest and metal is harder than rubber.

[jijifer]

Just a thought here, These are the 90* stems, correct?

Think about the procedure of checking the tire pressure and the subsquent adding air.
Akward as it seems, use both hands, one supporting the valve stem from behind.
I'm thinking there's tearing caused when pushing on the stem at the rim's edge, that is the most vunerable part of the rubber part of the stem, where it is the smallest and metal is harder than rubber.

Mine have never failed (knock on wood). And I do just as you say - 2 handed setting it up but I use a bicycle pump so once on it's no handed.

This latest valve made it to 300 miles, the previous I think only about 150 not sure how long the first stem had been on there before failing. Now this friend isn't very good about checking his pressure. I'm only slightly better. Like I've wanted to do it since his failed and have ridden at high speeds for over 50 miles since.

The one time I *made* him check it - well checked it myself (long before the stems ever failed) it was under 20psi and i was like "you don't notice that when you ride?!" so to get me off his back he bought a fancy gauge seldom will use it. If the tire went low would any additional pressure be put on the stem?

So the long and the short of it, he isn't checking his pressure so that's causing the problem - at least as described.

[rajron]

When my front stem failed it wasn’t because of a bad rim, it was because the rubber on the stem deteriorated, it was as if it wasn’t UV protected. Many peoples suggested it was because of the ninety degree bend becoming fatigued during pumps ups, that wasn’t the case for me.

[charlie55]

Even though Genuine's stuff isn't made on the mainland, there's always the chance that some components may be sourced from there. That being the case, there are some known valve stem issues which may be pertinent to this thread:

http://scootdawg.proboards.com/index.cg ... read=21635

[jijifer]

thanks charlie.

the first 2 were the brass stems and this was a chrome one. I'm not sure if the manufacturer was different.

very curious. 3 failed in 4 weeks is a clear indication of SOMETHING I'm just not sure what!

[bikebuda]

there is something quite in common on this

if the rubber stem is not lubed properly when installed it will be stretched to almost the point of breaking befor it will seat in the rim so what i am saying is make sure
#1 they are using the correct size stem, they are smaller than the ones used on most autos but the auto ones can be forced to fit in the hole

and 2 make sure they use tire mounting soap or tire wax to make sure they dont ruin the stem on instalation

[Tocsik]

Oh man. You guys totally jinxed me today!
This thread was just revived today and now look what happened!

I have a habit of always squeezing my rear tire before riding; just to check. I think it comes from reading many posts on this forum talking about tire pressure etc. Plus, I came out to my scooter once after work to find the rear tire completely flat not long after having a new tire installed. Turns out it was the brass valve inside the stem just not being tightened enough.

Anyhoo, today, I squeezed the rear tire when I left work and it was fine but on the way home, something felt "off" with the steering. I pulled over and, sure enough, my frickin' valve stem was breaking down where it exits the rim!!! I always check and inflate my tires using two hands (one behind for support) and I often give the stems a visual inspection because of stories I have read about the stems failing.

Folks, give your valve stems a thorough inspection! Move them around a bit so you can see the part that actually sticks through the hole in the rim.

Darn it, I don't want to be without my scooter! I am going to look around on the forum and see how tough removing the rear tire is (I think I found it in the rear brake pad pdf). Maybe I will have time to drop it off at the shop midday and pick it up before they close at 6:00 tomorrow. Sucks that they don't open til 10:00 am.

Edit---Hey, the service manual lists the torque value for the rear wheel nut as 11 - 13 kg/m but what does it mean by"U type nut"? Looks like a regular ol' nut to me.

[n2tattoos]

Just a thought here, These are the 90* stems, correct?

Think about the procedure of checking the tire pressure and the subsquent adding air.
Akward as it seems, use both hands, one supporting the valve stem from behind.
I'm thinking there's tearing caused when pushing on the stem at the rim's edge, that is the most vunerable part of the rubber part of the stem, where it is the smallest and metal is harder than rubber.

Mine have never failed (knock on wood). And I do just as you say - 2 handed setting it up but I use a bicycle pump so once on it's no handed.

This latest valve made it to 300 miles, the previous I think only about 150 not sure how long the first stem had been on there before failing. Now this friend isn't very good about checking his pressure. I'm only slightly better. Like I've wanted to do it since his failed and have ridden at high speeds for over 50 miles since.

The one time I *made* him check it - well checked it myself (long before the stems ever failed) it was under 20psi and i was like "you don't notice that when you ride?!" so to get me off his back he bought a fancy gauge seldom will use it. If the tire went low would any additional pressure be put on the stem?

So the long and the short of it, he isn't checking his pressure so that's causing the problem - at least as described.

ha! she's talking about me. ok, ok! i'll start checking the pressure!

[jijifer]

So that's the exact same stem I have in my new rear tire. How much play is too much play in a stem?

[Dean F]

NCY valve stems at Scooterworks for $4.99 each.

[Tocsik]

NCY valve stems at Scooterworks for $4.99 each.

Yeah, but they only have 'em in blue! They do look pretty sturdy though!

My tire is at the shop right now getting a new valve stem. Unfortunately, the one they took off the shelf looks like the chrome one in the above post so we'll see how it does.

[charlie55]

A bit pricey, but check these out for color and style:

http://kurveygirl.com/shop/index.php?cPath=27

[rajron]

I didn’t know those two piece o-ring stems were made for our style of rim, thought they fitted onto thinner rims.