Tires go flat

[gixerman]

My 99 Hayabusa has a wierd thing happening. I had dunlop 207's...switched to 208's this year. First the rar went flat going about 65mph, instant flat. Filled it up checked everything and it stayed full. We checked everything, it's frustrating. Now it is happening to the front tire, going crazy..I never heard of this before. TIres new check, clean rims no dings, good valve stems core, good everything. What gives? I have no confidence in my tires at all, screws up having fun worrying all the time. Anything anyone might know please let me in on it. Thanks

 

[gararnett]

Do you have metal valve stem caps? What type of valve stem cap are you running? If no cap, you could have picked up debris in the stem causing a loss of pressure by depressing the core inward. Don't use the caps that check/warn you about your tire pressure, they are like running without a core at all. Use a metal valve cap that has an o-ring in it which will work as a backup to the core, preventing further loss of air. Also important when running at higher speeds as centrifical force can cause the core to move in just a little and release some air.

But the second read of your post, I would bet that the bead was not fuly seated on your new tires. When it finally seated, due to a move of the tire itself, there would have been a loss of pressure, which could have been relatively significant. Or the valve stem was not properly seated/leaking (if it is rubber and not a metal screw on type) and eventually seated properly.

 

[dezzy7]

ounds like the tires are sealed poorly on the rims, you may wanna break the bead and reseat them

 

[MET]

I would agree with the guys on this one...

 

[Dae]

hi, just read an article about this problem. it is as GARARNET describes. when the tyres get hot and along with the forces applied air escapes into the dust cap, pressure builds and actually pushes the valve in and releases more air. this is a common problem with the cheap aluminium dust caps. this was in STREETFIGHTER magazine this month.

 

[IG.]

Hi, everyone,

New member here. Going to get a 'Busa this fall, or next fall when the price is a bit lower.

Anyway, I ride Katana 600, and one day I had a weird problem. I come to the bike, and my rear is flat. And, that's two weeks before the track day.

So, I am cursing and thinking how could this happen. I need to put the bike on the centerstand to take off the rear, but I cannot do it while the tire is flat - bike is sitting too low. So, I figure I will pump the air in. Even if it leaks, It will help me to put her on the centerstand, and then I will look for the puncture.

I pump the air in, wiped the tire clean, and look for the puncture. Nothing. Then I am checking the valve - put some saliva on the valve. Wow! The damn thing leaks. I am like, whew, I will just replace the valve core. So, I don't even bother to deflate the tire by pressing the valve in. I just use that small tool, and unscrew the valve core.

Then I carfully examine it, and what do I see. There is a microscopic piece of rubber or something stuck there, not letting the valve to stay completely closed. I blew the sucker away.

I put in a new valve core anyway, but I would've never believed this if I didn't see it myself.

 

[FLCN72]

This might not have been an issue here. But try to avoid using gas station air in your tires. Those compressors are often dirty and can blow dirt, oil, and crud into your tires which can mess up the valve stems.

 

[IG.]

This might not have been an issue here.  But try to avoid using gas station air in your tires.  Those compressors are often dirty and can blow dirt, oil, and crud into your tires which can mess up the valve stems.

Yep... Now I know, but don't have much of a choice.