losing tire pressure

silverhawk · Jun 1, 2014

Hello, I have recently gotten a 2011 FS570 and enjoy it tremendously. I have been noticing that it looses tire pressure quickly. I don't know much about tubeless tires, but within a weeks time my tire pressure goes from 26psi front / 23psi rear to 20psi front / 12psi rear. Seems like there is something wrong to me or is this normal?

Thanks,

Jen

akshun · Jun 2, 2014

Over a long time, normal. Over a week, perhaps you have some slight leakage? Valves tight? Clean beads? Quality tyres/ rims? Dented rims?

Idle · Jun 2, 2014

Dish soap and warm water, about 1/3 soap 2/3 water.

Put it in a spray bottle, air up to 40-50 psi then spray it everywhere it could leak, including the uncapped valve stem.

Then report back with where it's leaking.

Ps. I think you have your tire pressures backwards..

I run 23 front 26 rear for pavement, or 24/27… Well, unless it's all dirt riding in which case it's 18 front, 16 rear.

The FS570 and KTM 690 supermoto both use a special rim and a rubber rim band that tucks into a lip in the drop center to seal the spokes.

HusaBELGfs570 · Jun 3, 2014

That rubber sealing band that's in the rim could be damaged/reason why you are loosing air it is adviced to replace them every few years (do'nt know how many) anyway.
If you stick 1 tyre spoon to deep while mounting tyre it's enough to make a small tear/air leak in the band been there done that

silverhawk · Jun 3, 2014

I will check tires for leaks with the soapy water trick. As far as I can tell, the bike is in perfect condition and has never been dropped and the rims and tires are in fantastic shape.

I didn't know about the need to change the bands,so I will look into getting new ones.

Also, my manual says the tire pressure should be 26 psi front / 23 psi rear, so that is what I have been doing

Thanks and will let you know how it goes.:spin:

Jen

HusaBELGfs570 · Jun 4, 2014

also put soapy water on the rim where the spokes are if you see bubbles there it is the rubber band that's leaking inside the rim

Idle · Jun 5, 2014

That's a missprint in your manual, they swapped front and rear.

I'm 100% positive the pressures in the manual are right, but they are reversed.

A rear at that (23 psi) pressure will overheat at even a brisk pace in the twisties. Or straight line riding on the highway at 70 mph. 25psi is about as low as one should go, unless in the dirt or at low speeds. Highest is 30, but the edges can get greasy.

Back on topic, have you figured out where it's leaking?

silverhawk · Jun 7, 2014

Thanks for the info on the tire pressure. I checked the valves and now the front tire is holding pressure, but the rear is still leaking and has increased to every few days of needing air. Can't find it leaking by just spraying soapy water on it, so I will try a bath to see where the leak is.

Jen

ALARKA · Jun 8, 2014

Check around the valve also and FWIW I run Bridgestone 003R tires at 24/24 F/R and found that is the optimum PSI for the Mtn's I ride in but I do run aftermarket wheels Faba/Marchi on 2 different bikes with 5.5 Rear wheels with 160 tires but the front is still a 120/70 and my friends run the same tire run 24 PSI F/R as well even on with the stock FS wheels but with a 150/60 BS 003R.

silverhawk · Jun 9, 2014

That's a missprint in your manual, they swapped front and rear.

I'm 100% positive the pressures in the manual are right, but they are reversed.

Everything on the bike and manual say the same thing about tire pressure, 26psi front / 23psi rear. I can't imagine they would say the reverse everywhere on the bike.

I haven't had a chance to check why the rear is so leaky now, but hopefully this week.

Thanks everybody,

Jen

silverhawk · Jun 11, 2014

After using a water bath, there is a small whole in the tire, probably a piece of glass. This explains why the pressure fell so fast the past two weeks. Also explains why the front tire is holding pressure after tightening the valve core, but the rear didn't. The valve core on the rear and all the spokes held up under water. I will have to fix the flat tomorrow and be on my way.

Thanks for the suggestions,

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