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I've been riding my 150 vespa for 1700 miles so far.... everything has been gr8 - i went to ride it the other day and the front tire was totally flat. i could push on it and there was no pressure. maybe zero. I had last ridden it less than a week ago.

I filled the tire up to 30, (over pressurized it) and a day later, it's at 29. which means it either lost a little or no air --- just taking the pressure OR measuring difference could account for the difference.

Any ideas?? I'm mystified. If I lost the air while riding --- man, it was so flat, I shouldn't have been able to steer it.

I guess i don't want this happening when I'm going 60mph or something..!

Thanks!
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I've been riding my 150 vespa for 1700 miles so far.... everything has been gr8 - i went to ride it the other day and the front tire was totally flat. i could push on it and there was no pressure. maybe zero. I had last ridden it less than a week ago.

I filled the tire up to 30, (over pressurized it) and a day later, it's at 29. which means it either lost a little or no air --- just taking the pressure OR measuring difference could account for the difference.

Any ideas?? I'm mystified. If I lost the air while riding --- man, it was so flat, I shouldn't have been able to steer it.

I guess i don't want this happening when I'm going 60mph or something..!

Thanks!
Quote:
How about trying a tire shop? They can check to see if you perhaps ran something over?
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It may be a faulty tire valve. Whatever the cause, find it and fix it before you risk riding again!

Ride safe & have fun! 8)
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ok --- i thought i could figure it out myself ---- i kind of prefer doing that, because mechanics sometimes seem to take the expedient way out... there's a shop near my house, and i'll carefully ride the vespa there. i assume you guys feel it's unsafe to ride a bike that has a mystery flat.....
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Do you have a spray bottle of simple green ? Put scooter on center stand, spray the front of the tire tread. Look for small trail of bubbles. Rotate the tire backwards as you lift a little to turn it. Spray more, repeat. You have to look close for small bubbles between or on the thread of the tire. If you find it mark an "x" with a yellow crayon .If all ok, remove air valve cap- spray it, look for bubbles. Rinse everything off with water when done. Be careful you don't knock your scooter over. Let us know what you find.
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If i leave mine for a week it'll drop pressure quite considerably, losing 1psi isn't worth worrying about, the difference between a warm tyre from riding or left in direct sunlight would be greater & as you said measuring difference.

For peace of mind just mix up some washing up liquid or kids bubbles & brush on, rim, valve, any suspicious looking spots, maybe check the valve core itself, just make sure to wash it off before riding
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Flat front tire
You are fortunate that it is the front tire, much easier to deal with than the rear tire. While spraying with a mixture of a little dishwashing soap and water works, the real sure fire method is submerging the tire in water. The front tire is easily removed and you probably have a container you can use to at least get the bottom half of the tire submerged. The wheel is small enough to fit in a large cooler for example. Fill the tire with at least 26 pounds of air pressure, remove the valve cap, submerge the tire and let it sit for a minute or so. If no bubbles seen rotate it so the next portion of the tire is submerged and repeat the process until you have checked the entire tire. Pay special attention to the valve stem and gently wiggle it looking for bubbles while submerged. Be sure the tire is submerged enough to include the rim as leaking at the tire bead can happen. I once had corrosion occur inside the rim causing the tire to leak at the tire bead. After years of no problem all of the sudden the tire started losing air (see attached photo). Good luck.
Forum member supplied image with no explanatory text
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I vote for a faulty valve stem. Also it's really easy to let more air out when you check the tire pressures. Ask me how i know. Been there and done that. How old is the tire and check the tire for holes like others have said. I'm betting you accidentally let the air out when you checked it. When ever i change a tire i always change the valve stem too. Good luck
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Drastic drops in temperature have caused my car tires to lose a lot of pressure overnight. That's another possibility to consider.
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Hi, I totally get wanting to figure it on your own. I do know when I've taken my car to the tire serving center they did not charge me to inspect the tires, nor fill them.
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I have managed to plug a number of small holes. I always find them after a few minutes using soap water. Then just plug it using a "Tire Plug Kit". So far I have fixed it every time. Once I figured that it was not normal that I had to fill the tire up a little bit every weekend and sure enough a tiny little hole was detected using soap water and patience. I have never had to remove the wheel either, that is for the workshop
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Re: mystery flat front tire!!!
doublegregg wrote:
I've been riding my 150 vespa for 1700 miles so far.... everything has been gr8 - i went to ride it the other day and the front tire was totally flat. i..!

Thanks!
You did not say whether you took a look for anything stuck in the tire?

It could be something as small as a staple, brad, tack, piece of wire and can be in the tread groove or on the pattern.

Advice to spray soapy water on tire as you inspect is helpful in this process
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Thanks so much for all the replies... I will try to look at the tire again on wednesday or thursday. In answer to a couple questions - I checked the tire - nothing obvious. I tried plain water - but not the soapy kind. So I will try that - I guess I could try that on the valve stem.

It's been almost three full days, and it's only lost a pound or two - which is partly from checking the tire every day.... measuring error.....

I'll let you all no.... and, yeah, although I'm not experienced at tire things - it's sort of a mysterious leak - in my OP, wow - it was empty. that seems like a mystery. we'll see...............
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I've had a mystery 'instant' flat tyre on one of my son's bikes. We worked out he'd not checked pressures for ages so the pressure was probably low to start with - and he reported hitting a major pot-hole hard enough to nearly throw him off. We surmised the tyre bead had momentarily parted from the rim, and allowed most of the air to suddenly escape. When we pumped it up again, it held pressure just fine.

So although you've probably got a puncture, it may not be that if you've hit any pot-holes recently.
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I also had a 'instant' flat on a motorcycle I was riding after hitting a pothole. This was my old Harley that used tube type tires. There was no puncture in the tube. All I had to do was inflate the tire again.

There are a couple of different types of valve cores that I've run across. Some are spring loaded and the spring ensures that the valve closes properly. Others use the pressure in the tire to keep the valve closed. My old Harley uses VERY low tire pressure (16-18psi is the recommended pressure). When I got my flat I had one of the valve cores installed that does not have a spring for positive closure. I can only guess that when I hit the pothole the valve was jarred open. Then because of the low pressure and centrifugal force on the valve as the wheel spun, the valve stuck open and released all my air very quickly. I don't know if that's what happened, but it's the only scenario I could come up with.

-Craig
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CASCH has a good point. I see you have a 150. What type of valve stem do you have on it? Is it a straight one or curved one? My friend who had a 150 got her new tire put on by a MC dealer here and they put a curved one on. She had a instant flat when she had just exited to the airport. Now it was the rear tire, so i don't know if that makes a difference (might because there's not a lot of room back there) but you might want to swap it out and see what happens. I've had tires lose a lot of air pressure when the temp dramatically changes but it's never gone flat on me.
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My gts rear valve stem had to be replaced - after about 8 months of use, I was washing it and noticed that when I pushed/tilted the stem a certain direction, it let by.
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If you don't see anything in the tire. I would next replace the core pins in the schrader valve, very cheap at an auto supply, tighten with the little prong tool, not gorilla-tite. My neighbor has this old "pacer" moped which needed a tire fill every ride. I dealt with this for years, but recently came across some new pins I had in my garage. Put them in the Pacer. The tires now do not lose any pressure. Much easier to try than a new tube.
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Thanks for all the replies.........I went to the local shop, which is where I had bought my bike. The guy seemed not that concerned about my total flat from the bike just sitting. He asked if someone might have let the air out - I told him it was in my garage -- btw, it is secure.

He felt I might have a slow leak (this doesn't explain the total flat, which happened either on my last ride or within 5 days of the vespa sitting in the garage - or both....). If I have a slow leak, he said get a new tire......... I notice some people PATCH their tires....

So - upshot --- I assume the tire is SAFE to ride, although I need to check for a slow leak. It seems to lose a little air pretty slowly - a little being MAYBE losing a couple pounds a week???

I still having tried the soapy water with the tire still on the bike. the leak seems just so minimal - I'd guess it's leaking....but not sure
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Could be a bad rim. How old is your bike? Also you might want to throw some Ride On in the tire. My tire (rear one) went through a period where it was losing more air than it should. The weather, i think had a lot to do with it. That said i threw some Ride On in it and then the weather stabilized. Both or one of the things i did worked. Ride On isn't like Slime. Doesn't go everywhere when you take the tire off. It's used to stop little punctures from making your tire go flat. I'd swap the stems out as well. Use the straight ones not the curved. Good luck
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My bike has 1700 miles on it -------- the tires and everything on it looks gr8. If I put in str8 stems - anything special I need to do to reflate the tires? Actually, I've already inflated it from flat, since it went mysteriously flat.. I hesitate to put product in the tire to seal leaks, but if Ride On is acceptable, maybe for a small leak it would be fine? The alternative is, as my shop guy said, just spring for a new tire. Which seems like it might be overkill, but I see where a tire is critical to one's safety..........

Btw, the front tire on a vespa is so small, that I really don't like even the bump from some driveways - where the lip meets the gutter. It feels like 'rimming' a bike - when the tire pressure is too low and the rim bottoms and cuts the tire. My front tire pressure is fine when I experience this, btw.
judy wrote:
Could be a bad rim. How old is your bike? Also you might want to throw some Ride On in the tire. My tire (rear one) went through a period where it was losing more air than it should. The weather, i think had a lot to do with it. That said i threw some Ride On in it and then the weather stabilized. Both or one of the things i did worked. Ride On isn't like Slime. Doesn't go everywhere when you take the tire off. It's used to stop little punctures from making your tire go flat. I'd swap the stems out as well. Use the straight ones not the curved. Good luck
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I have a 150 also. They have small tires but if your running it with the stock shocks that's normal. The stock shocks suck IMHO. I have Malossi's on mine with Clauss Studio bushings. What kind of tires do you have on it? I use Heidenau's. K61 up front and a K62 rear. I like Ride On. It also reduces my front end "wobble" that my bike has.
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I've got stock everything ---- afaik, everything is like new (i bought the bike new)... uh, 3 years ago, max? i hadn't thought of a new front shock --- did you just replace the front, or also the rear, and what do you like about it?

My chief experience with shocks is just with mountain bikes. a poor shock, and the bike seems to fight itself, the ride is kind of awful (over rough terrain) and out of control. With a good shock, the bike handles well - again, over rough terrain -since that's what the shock is for...... that is, handling well, not necessarily comfort, although it helps w that too.........My friend and I got the best shocks that were available for our mtb's.....

but going over a certain driveway lip -- it's like, 3/4"? i slow down really slow b4 i go over it.... otherwise, the tire just feels like it's going to hit the rim. That's what it feels like, don't know if that's actually what's happening.

btw, I weigh 150 and never ride two up.....

thanks!
judy wrote:
I have a 150 also. They have small tires but if your running it with the stock shocks that's normal. The stock shocks suck IMHO. I have Malossi's on mine with Clauss Studio bushings. What kind of tires do you have on it? I use Heidenau's. K61 up front and a K62 rear. I like Ride On. It also reduces my front end "wobble" that my bike has.
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Try sticking 80psi In & see if it pops, it may be it's not seated if it feels like you'll get rim strike, mine felt awful so I upper my pressure to mid 30s psi, the 23 suggested is certainly not for the tyres I have on, you should see what pressure the manufacturer recommends
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I have Malossi's on both front and rear. Adjustable and i find the bike rides way better. Stock shocks don't even come close. The 150's are small and you really have to go slow over big drops but it's doable. I don't take mine on the freeway but ride all over the island on the secondary roads. Have almost 42,000 on him and i'm never going to go higher. Back in the 80'ss i had a Honda Helix 250. Heavy and huge. My back can't take that anymore, so the 150 is what i ride.
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Also have a couple of decent tire pressure gauges as reference. For years rode my duke 5 psi too much. The "quality" dial gauge I had used for years thought accurate. Psi more critical on two wheels. Set psi by your book, not what it says on tire.
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