Leaky Tubes

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  #1  
Old 05-31-14, 08:13 PM
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Leaky Tubes

The tubes on my Honda CRF230F were leaking when I purchased the bike a month ago, so I replaced the tubes with new heavy duty tubes. However, I lose about 4 to 5 psi over a weeks period, even with the bike supported on a stand. How is this possible? Do I need to tighten the valve cores more? I tightened them until they were snug and didn't want to crank down on them too hard in fear of damaging the rubber seal.
 
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Old 05-31-14, 09:04 PM
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sorry for my ignorance, but what tubes? What psi are you losing? Forks?
 
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Old 06-01-14, 04:19 AM
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Sorry. Tire inner tubes, 15 psi.
 
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Old 06-01-14, 04:43 AM
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I wonder if there are thorns in the tires. I have the same problem with my mowing tractors. The next time the tires are off run your bare hands over every inch of the inside of the tire feeling for them.
 
  #5  
Old 06-01-14, 04:45 AM
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Use water to check the valve core for leaks. Are you sure you didn't pinch the tubes when you installed them?
 
  #6  
Old 06-01-14, 06:47 AM
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Ya, a 4-5 psi loss is a bit much imo.

So, in addition to the suggestions above, I'd air the tires up to the owner's manual specifications and then let them sit for an hour so. Then check the pressures again and see what you get.

I say this because air compressors tend to heat the air they pump up enough to give you a slightly higher psi immediately after filling the tire than what you'd get with a "cold" reading after the tires have sat long enough to let the air cool down.
 
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Old 06-01-14, 07:00 AM
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Lost my last post. I'll try again.
Trick for locating the thorn or other foreign object is to mark the location of the valve stem on the tire. Once the tube is removed and the hole identified, reposition the tube next to the tire to locate the origin of the hole. if you flipped the tube you have to check both locations.

Bud
 
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Old 06-01-14, 08:32 AM
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Tires have spokes? Did you replace the spoke protector inside the rim? Did you check all spokes for tightness?

If loose the will put a hole in the tube... But chances are large that both tires would have spoke issues

And no its not normal to loose all that pressure...

I never lost pressure on my bike and it stayed very constant.. Only winter/summer pressure issues...
 
  #9  
Old 06-01-14, 06:44 PM
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Checked the tire bands, they are good. I was very careful and didn't pinch the tubes, and I have not checked the inside of the tires themselves for foreign objects. However, when I removed the old tubes and re-inflated them I did not see any air bubbles whatsoever when submerging them in a bucket. Kind of puzzling. After a day of riding yesterday, the pressure hasn't changed. I should also mention that I am using the gauge on the air nozzle attachment which only goes down to 10 psi. Not sure how accurate it is at the lower limit. I used another handheld dial gauge and it reads a few psi less. Not sure which is accurate, but at this point I'm looking for a delta. I'll check again in a couple days.
 
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Old 06-27-14, 09:46 AM
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I tightened up the valve cores on both tires and the rear tire held pressure for 1 1/2 weeks thus far. However, the front tire dropped 3 psi. I'm going to replace the front core and make sure the inside of the valve stem is in good shape as well to ensure there's a good seal between the stem and core. I may just replace the core with another since I have a new 4-pack sitting in my toolbox.
 
  #11  
Old 11-20-14, 11:42 AM
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I'm still having issues with my tire pressure. I haven't been keeping too close an eye on it, but I have to add air every time I go riding, which is about once every three weeks. Not a big deal, but annoying nonetheless. I have a general question--if the atmospheric pressure is 14.7 psi and schrader valves are held closed by the air pressure exerted from inside the tire, then how on earth does the tire hold pressure if less than the atmospheric pressure? I keep my tires at around 10 to 12 psi so wouldn't they be prone to leaking?

...hold on a second, are my valves supposed to have springs??? They sure as hell didn't come with springs. The pins are definitely not spring loaded because they wiggle around fall inside the valve when held upright.
 

Last edited by mossman; 11-20-14 at 12:25 PM.
  #12  
Old 11-20-14, 01:11 PM
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You can screw out the valve core and replace it if needed.
 
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Old 11-20-14, 01:42 PM
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You can screw out the valve core and replace it if needed
I've already done that twice. No improvement. New tubes, new tires, new valves, and tires lose pressure over a week or two. Are schrader valves supposed to have springs in them?
 
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Old 11-20-14, 01:53 PM
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I think they might but it's part of the valve core, not something separate.
 
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Old 11-20-14, 02:02 PM
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I think they might but it's part of the valve core, not something separate.
Right. There is supposed to be a small spring internally that holds the valve shut. However, all of the valves I have used do not have springs. The pin is loose. The replacement valves that came with the tubes didn't have springs and the pack of Slime valves I bought at the store are also loose.
 
  #16  
Old 11-27-14, 05:47 AM
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Have you mentioned your problem to the local Honda dealer?

What are the other local riders experiencing with their dirt bikes?

You really should have a good tire gauge to check pressures.
 
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