Lost Half My Air

Clyde

Clyde

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I hopped on the bike after work yesterday to ride home and the handling was for crap. I stopped before I even left the parking lot and checked my tire pressure and the front was down from 38psi to about 20psi (i had just checked it in the morning and had . I checked the tire and couldn't find any signs of a puncture, so I rode over to the nearby gas station and filled the tire back up to 38psi and rode home. By the time I finished my commute, it was down to 36psi.

I sprayed some water on the valve stem (90-degree -- purchased from a SlowBoyRacing on this forum) and it's leaking from the "base" of the stem. When I put pressure on the valve (checking or filling), I can hear air escaping. It doesn't appear to be a loose core, and the air escapes with pressure on the stem but not the valve core itself.

I didn't install them, but it looks like there is a nut that goes on the inside of the rim. Since I can rotate the stem fairly easily, I'm assuming that nut backed off a little and is letting some air leak through the rubber seal.

Is there anything I can do without taking the tire off?

Like I said, I tried rotating the stem (clockwise), and it didn't seem to tighten up after one revolution. I'm pretty sure I have to pull the rim off the bike, then take it to the shop and have them unmount the tire, tighten (or replace) the stem and put everything back together again.
 
I installed a pair of Ariete 90 degree stems with my new PR2 CTs last month. There is a nut on the inside of the rim and you're going to have to dismount the tire to re-tighten it.
 
Yeah, that's what I thought. I pulled the wheel off this morning and will get it to the shop before I go to work. This damned "early riser" stuff is great when it comes to getting things done, but the shop doesn't open until 10am, which puts a cramp in my work day.

I promised a new rider that I would help him out this afternoon, and I really don't want to renege.
 
oh, I had problems with those 90 degrees valves too

thing is they have an o-ring ... but it sits on the outside of the rim, and on the inside there's nothing keeping the air in.. a really dumb design

I have some stock but will not install them anymore
 
I had the exact same problem with one of the values I purchased from the same person. I replaced it with a regular one and all is fine. I don't know if this was a fluke or the beginning of a pattern. Unfortunately I have several others installed. I guess I'll watch them and replace them as they fail.
 
Sebastian F7 said:
Would putting blue loctite on keep the nut from backing off and prevent these problems?
Click to expand...

don't think the problem is the nut backing off, it's aluminium on aluminium, if it was torqued by the tire guy it won't come off
I think it's the rubber ring that fails...

I put some tire sealant on them when I install, it helps.
 
I also had a problem with these 90* valves, they are not the exact size and will not seat properly, Had to purchase bikemaster brand from a local shop.
 
I've been using the Slow-Boy 90's on the YZF for just over 3,000 miles with no issues at all. I think I've lost maybe 1psi over the course of 2 weeks when the bike just sat. Other than that they have been great. The only issue with them is that you can't install the Dyna Beads the traditional way with the angled stems. Not a big deal though.
 
When I took the tire in to the shop, we discovered that the rim was slightly bent. I honestly don't remember striking anything hard enough to bend the rim, but apparently I did. I think that this was probably a contributing factor to the valve failing. They forgot to give me the old part back, so I'll pick it up today. From what I understand it was the o-ring that failed.

I'm riding on it for now (with a new valve stem) and have fully refreshed my memory on why I got the 90's in the first place. Checking/filling is a PITA on the front tire!
 
Have them on both of my tires and have had no issues....tight as a drum. I left this summer for 2 months and each tire lost 2 psi in that time....that is far less than my experience with the regular style ones and the leakage could be through the rim just as much as through the valve. If they are installed correctly (torqued correctly) and are the right size they work fine ... many shops don't know how to install them. Tens of thousands of Ducati's, Triumph's and other brands have them as standard....they do work.
 
I have the cheap EBAY/CHINESE units. Probably from the same/similar manufactuer. No problem with them. I sprayed silicon on the O-ring and used medium loctite on the nut.

I dont think that the bent rim would be an issue.
 
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