Outer Limits 4x4 Board

Posted: **Wed Nov 18, 2009 8:01 pm**

Hi,

I've got a small (eBay) style compressor. I was trying to pump up some tubeless tires on my mountain bike, but I couldnt get enough volume out of the unit to seal the bead.

So ... been dumb I though what I need is something to store up some volume, so I picked up a small 7ltr air tank (also from eBay). When I was plumbing it all together, I realized I should get an air-pressure switch for the pump, so I got a 100PSI 12v unit off ebay.

Now I can fill the tank with air and build it up to about 100PSI but it still wont pop the bead and seal up MTB tyres. I know I can go to the servo and it works every time, but I'd like to be able to do it myself, and I've gone this far, so whats missing ?

Current setup goes like this:

Code: Select all

Compressor --> Check Valve --> T piece --> Tank
                                   |
                                   v
                              Coil Hose
                                   |
                                   v
                           Car Style Nozzle

[/code]

Posted: **Wed Nov 18, 2009 8:32 pm**

I'd suspect that the fittings/tube are providing enough restriction to cut your flow-rate.
Check the inner-diameters of both (quick test - compare empty-time with and without hose-and-fittings).

ed

Posted: **Thu Nov 19, 2009 6:58 am**

what pump have you got?
odds are you may kill it pumping up to 100psi.

have a look at the nozzle it may have a tiny hole. you need big air flow to pop the tire on. 7ltr tank may not be big enough. it may be easier to resort to the old spray can and lighter

Posted: **Thu Nov 19, 2009 6:41 pm**

Youre setup looks fine from youre diagram. If you are getting the tank to 100psi, then about teh only thing that could be wrong is not enough flow through the fittings as someone has already mentioned.
Maybe even try taking the core out of the schrader valve in the tyre, just so you can seat the bead, or is that not how bike tyres work?

Posted: **Thu Nov 19, 2009 10:45 pm**

Hi Folks,

Thanks for the tips. It could well be the hose & nozzle, it's just a cheap job from bunnings.

The pump is pretty expendable, its a cheap import one, its *supposed* to pump up to 150PSI, but it does take a minute or two to get the tank up to pressure (gets pretty hot too!).

If/When it goes bang I might look at a "proper" BOSS one, but I'm not using it for anything serious like air-lockers though.

I noticed an air-tool shop near work, so I might pop around there and see what I can find. Ideally something with a presta fitting would be perfect, but I have a presta->schrader adaptors on the wheels.

Thanks again for the tips.

Posted: **Fri Nov 20, 2009 7:22 am**

cheap ones don't have very good seals and do not handle the heat. ok for doing low pressure stuff like pumping up tires but high pressure kills them fairly quick.

what flow is it rated at ?

Outer Limits 4x4 Board

Air Compressor - HowTo ?

Air Compressor - HowTo ?