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Tyre Pressure Drop - curlylegend - 05-09-2022
This has got me puzzled...?
My 1991 3VD TDM850 had been parked up in the garage for seven days after a 200km run and apart from the battery being put on charge nothing had been done to it.
Without fail, every time I take my bike out, I give it a fairly thorough check-over. Lights, chain, etc, and especially tyres, including pressures. So, I was a bit disgruntled to find my rear showing 0.85 bar instead of 2.70 bar ! Seven days previously the bike had handled faultlessly especially on the twisty section just before home. I assumed I had picked up some sort of penetration on the last few kilometers and resigned myself to a close examination of the rear tyre to find the damn thing and if possible to effect a repair.
I reinflated the tyre, a Battlex BT023 with on average 6mm tread, to 2.70 bar and then carried out a meticulous check for a nail or screw or whatever.
Found nothing ! Â
I dismounted the wheel to check for bubbles while immersed in a bath of water.
Not a single bubble !
The valve was new with the tyre about a year ago and the seating at the rim showed no signs of leakage. So I left it as it was and checked the pressure the next day, exactly 2.70 bar.
I gave it another 24hours then another pressure check showed absolutely no pressure loss. I remounted the wheel, went for a very brisk local run, and rechecked the pressure on return, which was now 2.85 bar but this morning, cold, was back to 2.70 bar.
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Was I imagining this ? Don't think so because I had to inflate the tyre with a floor pump and my shoulders protested for a bit afterwards.
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Any thoughts ?
Tyre Pressure Drop - Pedro - 05-09-2022
Sometimes, just sometimes, the core in the tyre valve can unseat itself and not seal properly. Pumping it up again would have moved it an maybe re-seated it. It may be a good idea to remove the core and give it a clean. It has happened to me on a car. Either that, someone was messin' with ya!
Tyre Pressure Drop - curlylegend - 05-09-2022
Quote:Sometimes, just sometimes, the core in the tyre valve can unseat itself and not seal properly. Pumping it up again would have moved it an maybe re-seated it. It may be a good idea to remove the core and give it a clean. It has happened to me on a car. Either that, someone was messin' with ya!I remember reading years ago that Schrader made a specially strong racing spring for valve cores. It was thought that a high enough centrifugal force could overcome the spring pressure and unseat the valve. Just like you said.  However, honest guv, I never went that fast !
Good point though, I'll take out the core and give it a close inspection, maybe even replace it.Â
Tyre Pressure Drop - Studley Ramrod - 06-09-2022
Is it possible you could have gotten a false reading when it showed 0.85 bar ?
Tyre Pressure Drop - curlylegend - 06-09-2022
Quote:Is it possible you could have gotten a false reading when it showed 0.85 bar ?Don't think so. I checked the front at the same time and got a reading of 2.50 bar as expected. I then re-checked both tyres with my analogue gauge, same readings...front 2.50 bar, rear 0.85 bar.
Tyre Pressure Drop - ChrisG - 06-09-2022
Private garage rather than a communal one where someone could have tampered with it?
Tyre Pressure Drop - curlylegend - 06-09-2022
Quote:Private garage rather than a communal one where someone could have tampered with it?Decidedly private ! And I'm living here on my own, my wife has been in the Untied Kingdom for the last two months. Â
Tyre Pressure Drop - marko67 - 06-09-2022
It's much easier if you use your foot to pump it up. Having said that I bet you can do a lot of press ups.
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+1 on a valve rattling around. Make sure it's properly screwed in.
 " I had to inflate the tyre with a floor pump and my shoulders protested for a bit afterwards.
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Any thoughts ?"
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