PX Brakes

[Colcam]

I got a new PX125 in January, and yesterday I was on a main trunk road, doing over 60mph, when the rear wheel just stopped turning, causing a very long skid, a very near miss with two HGVs coming in the opposite direction, and a nearly new tyre burnt through to the canvas.

Before the scoot stopped, the wheel suddenly freed again, and I crawled into a layby. Nothing obvious to see, so I had no choice but to carry on, nervously and very slowly, to a local garage some 20 miles further on.

Car mechanic I know there reckoned the brake linings had stripped, so foned dealer, the bike being under warranty, but didn't get a lot of help, though he agreed that was probably what happened and is getting new pads to me today.

What I want to know is whether this has happened to anybody else, and why, and is it ever likely to happen again, 'cos it was a bad moment and I really was lucky not to get myself killed.

Any help would be greatly appreciated.

[eugene]

Sounds more like a sieze than brakes.

[dave1967]

Hi
I would be very surprised if brake linings coming away would do that, without the metal part the lining would just chew to bits in seconds, i agree with eugene sounds like sieze to me but to be positive take hub off and check shoes.

[dto79px]

colcam said:

I got a new PX125 in January, and yesterday I was on a main trunk road, doing over 60mph

so foned dealer, the bike being under warranty, but didn't get a lot of help, though he agreed that was probably what happened and is getting new pads to me today..

is it a piaggio dealer or a spanner monkey dealer
would be shoe's not pads
over 60mph you were thrashing the life out of the scoot no wonder it heat seized the new px's run lean because there fitted with a catalizer
50 mph would have been a better cruising speed

[alanw]

Whenever this situation arises again pull in the clutch as fast as you can this will stop you skidding and reduce any long term damage
sounds like heat seize to me and have experienced it myself (lambretta)

[Colcam]

Sorry, shoes I meant to say. Hub will be coming off 1st thing in morning and will see then.

Those who suggested a sieze could be right, although the scooter has cat removed and a Poloni carb and PM Tuning exhaust fitted and cruises at a bit over 60 without being at full throttle.

Don't know if that makes a difference - I should have said all that in the first place.

Thanks all for replying.

[Colcam]

And Hell, I'm so dumb - would the bike go again after a sieze? When it happened engine didn't cut out or anything and the wheel unlocked before it came to a halt - in fact I didn't stop at all after the skid, would have got hit from behind probably, just drove on to nearest layby and everything sounded and felt normal.

Sorry folks, I've got a lot to learn.

[Spence]

Almost the exact thing happened to me a couple of weeks ago on the A55 in north Wales Col, and I was on a 200. As soon as I read the email you sent me I knew it was a heat seize you were talking about.

If you thrash a scooter at 60mph+ for long enough, and for some reason not enough oil's getting through in your mix, your piston will heat up enough to expand. If you're very lucky like you (and I) were, it just begins to stick suddenly, your back wheel will stop but because the piston hasn't jammed solid it'll release again. It usually takes a few minutes to cool down though, so for yours to free up again so soon you were doubly lucky.

But then, you do live near the north pole, so it's bound to cool down again quickly.

By the way, contrary to your other concerns, you're not the oldest forum member. Someone who shall remain nameless has got 12 years on you my friend.

[bryno]

It could have restarted once it un-seized, does sound more like engine to me, can't think what in the brake mechanism could get so jammed up on the hub to cause a lock up at 60

Does your back brake still work? if so, that's not your problem then..

[alanw]

back to the heat sieze, i always add extra oil direct in the petrol i have mallosi kit fitted, and i'm not convinced on long or high spead runs, the oil injection gives enough oil on kitted and modded machines

[bryno]

^ I've spoken to a few people on this issue since my Malossi seized, advice is extra oil in the fuel means less petrol for the same volume of fuel/oil mixture so it will actually run hotter and leaner..

I've been advised to stick with the standard autolube, or disconnect and pre mix but to the same ratio as standard.

[Colcam]

Thanks to all who replied on this, it's greatly appreciated.

Of course you were all right except me and the bloody dealer. I'd never have figured it out without all the help here.

Definitely a sieze, and the back brake is fine. There's an excuse for me being thick but not the Piaggio guy!

Anyway, new tyre now fitted, and I'll fiddle with more oil as suggested.

Spence, I know I'm near the North Pole here, but as it happens it was unusually hot on the day all this happened, so that may have contributed - and I'm happy to hear that I'm still just a mere lad.

(And I got a free set of shoes under warranty, which aint going back.)

[bryno]

Just check your main jet mate, do a full throttle run for about 2 miles, then clutch in, kill the motor.. when it's cooled take the plug out and check the colour, if it's very light, you need to go up a jet size.. personally I'd not put more oil in the fuel, check your jetting first, or just go up a couple of points in main jet size to be on the safe side anyway, can't do much harm running a tad rich..

[Lan]

just out of interest if this is a standard px 125 engine except the exhaust why do you have a carb kit on it??

[Big Al]

Can anyone tell me if the heat seize problem affects T5's too? Mines unlikely to be hitting 50mph+ in London but is IS painted matt black, and we're looking at a blistering summer this year...

[bryno]

Not on the standard motor mate, but when you stick that 172 kit on it

[Colcam]

Thanks for all the help. Upped the jet size, and trying a cooler spark plug, seems fine but... now the clutch is giving me severe headaches after being back on the road for a day.

[guppstah]

I had this years ago on my V90, had you pulled the clutch in you would have just rolled, but as you obviously didn't you skidded, and when the engine unseized it has bump started and on you went.
I would have thought that over 60 was pushing any fairly standard px125, I certainly wouldn't try and cruise at that speed on my T5, probably 50 max.
Would it be a good idea to check the piston and bore?? ( I am not the one to answer that)

On a separate note, you said that it is under warranty, and that the dealer was sending out new shoes to you.
If it is under warranty should they not fit them too?
Although its not a difficult job, I thought that was the point of the warranty.


Gaz