I've been constantly battling a problem with tyre leak down on my tubeless rims. (Don't ask how long for. I'm too embarrassed to say) I'd pump the tyres up to 28-42 (old pressures) in preparation for a ride and by the next morning, both would have dropped to 20lbs each. Didn't matter how long I left it for, they'd stay at 20lbs. Sprayed some soapy water all over the wheels and all I could detect was an occasional bubble coming from the base of the valve stems. I mean occasional. I couldn't see how a leak that slow could deflate a tyre so much in a short period of time.
Anyway, dropped around to see Steptoe the other weekend and during my visit, I checked out his rear tyre, which he'd had fitted the same time as mine. Ok, his was like new, and mine was about stuffed, so this underinflation thing was going to cost $$$ very soon, if left untreated.
So I picked up a pair of new valve stems from Kerry, our local man up this way, rode home, then set about replacing them. It's a drama to remove the front wheel from my bike due to the bulky caliper castings on the fork sliders, so I tried my hand at breaking the bead/s on the tyre in situ..
^ Shiny new Valve stems awaiting their fitting in the foreground
^ Weapons of choice - Much used and worn pair of 'F' clamps and some short bits of 3x2 pine.
^ Took a while to get the clamps in a position to actually crack the bead off the rim. Didn't want to use too much force for fear of maybe damaging the sidewall carcass of the tyre.
^ until it gave, and I could see the back of the stem
^ Wasn't too ugly inside the rim considering it's age.
^ Undid the stem nuts and wriggled the valve stem out of the rim
^ The old stem. Note the corrosion around the base rubber and the perished state of the outer rubber in the foreground
^ View of the recess the stem seal fits into. I gave this bit the cleaning of its life as I don't get in here often
The wheels fell off this job when I laid the old one down beside the new. Old stem has a straight 8mm shaft and the new one is a stepped variation. No way was it going to fit, so all I could do was clean up the old stem as much as I could, and miraculously found some new rubber seals that fitted snugly, then reinstalled the old stem with a new valve core and prayed.
At this point, I returned the new stems which had Kerry mystified, as he'd only used these ones on all the bikes he'd come across, and that's a lot of bikes. Must be just that these were the first attempt at a tubeless tyre on a motorcycle and maybe changed to a different setup in ensuing models??
Anyway, we had a dig through his boxes and managed to find a stem with a 45 degree bend in it that looked like it would fit. I hoped so, as the 16" wheel with a straight stem had been problem for me since I first bought the bike, in finding a servo that had an airline that would fit it if I wanted to check the air when out on a ride, so this was going to solve two problems in one go.
Back in the garage......................
I found that the rear tyre wasn't going to be as easy to break the bead as the front due to the extra width, so I called in the heavy duty gear.
^ A couple of longer lengths of 3x2 drilled to take some 9/16" brooker rods and created a BIG clamp to squeeze the tyre together. I left on side a bit longer so it would rest against the rim on the far side to make it pop off on the lit (near) side. Well, that was my plan.
^ It worked!! I then worked the rest of this side of the bead into the well in the rim to make a bit more room where the valve was.
^ Having a wider rim was negated by the wider tyre, so it was still a tight fit to get the valve stem out.
^ I was disgusted that there wasn't even a rubber seal on the outside of the rim, which would've let moisture in to corrode the seat where the rubber sat
^ But after a good cleanup of the area (inside and out) I fitted the new angled stem
^ which bolted in from the inside.
With all the corrosion around the stems, I can see where the air was getting out. Maybe accentuated by the extra pressure and heat created by riding, with them all cleaned up and fresh rubber seals, and new valve cores, time would tell if this job succeeded.
5 days on, and I have just checked the pressures. Result = front - 36, rear - 42
Exactly where I'd inflated them to, so it must've worked..
