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Post by insideright on Jul 23, 2012 19:04:00 GMT
Evening Gents---------Travelling back from Midland Alliance get together at Ironbridge yesterday we were giving the scoots a bit of throttle and the above happened to me- back wheel locked and packed up left for a bout 10 mins and fine Any long standing damage  Is it just a case of over heating as the rest thought Can anything be done to prevent it happening again/is it likely to happen again.?? Thanks |
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bsr65
High Number
Posts: 114
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Post by bsr65 on Jul 23, 2012 19:50:04 GMT
what model of vespa do you have? is it kitted? if that happened to me id want to take the barrel off to check for damage, id check the colour of the plug, autolube function, and main bearing oil seal.
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Post by kru251 on Jul 23, 2012 21:24:18 GMT
Had a lLambretta Li125 do that while trying to keep up with chaps on faster scooters. Pinned throttle wide open etc. In my case the last twice it happened in just those flat out circumstances. After restart engine fine. I was told that it can even have beneficial effects as it knocks the high points off the piston. Engine may sound noisier, but will run better. BS? I don't know, but my 1962 125 with my over 16st weight on it is fine as long as not thrashed for tooooooooooooooooooooooooo long!!!
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Post by sbwnik on Jul 24, 2012 1:37:15 GMT
Never heard that theory before, and I have to say it does sound like BS to me. A seizure can gouge the cylinder and/or piston, but I've never come aross one that's come off better!
Pop the head off, and run your finger round the cylinder and feel for any obvious scratches in there. Ideally, you'd take the cylinder off and give it a thorough visual check, but in my experience you only need worry if you can feel any damage. Pay close attention to the exhaust port area. If you find any signs of damage, then it's time to take the cylinder off (come back and ask if you don't know how) and give it a thorough examination.
FTR my P2 has nipped up about half a dozen times over the years and is still on the original bore, it's never managed to damage it. They've all been after a prolonged run in hot, dry weather and I now know to take it easy for ten minutes in every hour of riding in this weather. One day I'll get round to sorting the cause. It's generally either timing or jetting that's the issue, but given the rareness of the event, I'll leave it a bit longer!
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Post by insideright on Jul 24, 2012 15:50:32 GMT
Cheers Chaps,
Its a PX 125 not kitted and a low mileage the weather sunday was hot and sunny and its due a service so ill go steady until it goes in for a service and get it checked out then.Many Thanks.
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Post by bryno on Jul 24, 2012 16:30:50 GMT
It's an old racers trick to thrash a new piston to death till it seizes then flatten off the high spot to make it run better (less likely to do it again)... but you'd be nuts to do that on a road going scooter IMO!
a hard seize is not great as it puts a lot of stress on all the components, imagine the stress on the crank when it was happily turning over at 6,000 revs then comes to a sudden halt, that can twist a crank as it did on a smallframe engine I have just rebuilt..
But thats unlucky, if it still runs fine, does not smoke or rattle, just keep on riding it, or if you are concerned, get someone to whip the head off and take a look.
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Post by Rudi on Jul 24, 2012 17:15:44 GMT
Cheers Chaps, Its a PX 125 not kitted and a low mileage the weather sunday was hot and sunny and its due a service so ill go steady until it goes in for a service and get it checked out then.Many Thanks. hi im curious, is the auto lube working? cause frankly ive been hearing a lot about vespa engines seizing, but ive been riding vespas for quite a long time and never had any hint of a seize even in hot weather and high speed (35 celcius) always used pre-mixed fuel, so i have a suspicion all these seizes are due to the auto lube not pumping oil properly... regarding benefits of a seize, there are none... only scared cylinder, piston and rings... |
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Post by insideright on Jul 24, 2012 17:23:48 GMT
Cheers Rudi I have my doubts as well regarding autolube a T5 i have with autolube seized on me at a relatively low speed im wondering whether to get it taken off and pre mix the oil for both the T5 and PX |
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Post by kru251 on Jul 24, 2012 20:49:57 GMT
Had pre-mix seize too so ?
Don't make the mistake of adding too much oil as it won't help. People often think extra oil must lubricate better. Reasons why it doesn't.
1) The two stroke oil burns hotter than a correct petrol/air/oil mix so actually raises the combustion chamber temp. More likelyhood of a seizure.
2) The more oil passing through the jets has the effect of weakening the mixture with the increased risk of seizure.
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Post by bryno on Jul 25, 2012 7:40:21 GMT
Lots of people are sceptical about using autolube and disconnect, way I see it, there are thousands and thousands of PX's running round the world pretty happily with autolube, I am only personally aware of one scooter which seized because the autolube stopped working (and that was an LML), so I'm happy enough to take the risk.
I think there is just as much risk of seizure without autolube as not everyone is accurate when adding oil themselves, adding too much or too little, I know people who just guess it - crazy!
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Post by sbwnik on Jul 25, 2012 8:24:33 GMT
I'm just going to repeat comments that I've made before:
My autolube did pack in a couple of years back, but you have to bear in mind that my scooter is a very high mileage machine - something that is probably very relevant. I've heard of (I think) this happening on teo other scooters in the last thirty years or so. Obviously there will be more, but I'll bet they're all down to wear and tear, at least one of the ones I know of did more miles than mine.
The 'running lean' theory is a good one in theory, but scooter engines aren't that precise. If they were, pre-mix engines would be for ever holing pistons as it'll be a very rare occurance that you measure out exactly the right amount of oil for your fuel when you've not put in exactly 5 litres. It's a theory that is probably correct in the old world of racing two-strokes where toleances ae very tight, but on a mass produced machine that has the ignition set to 'best average' it's unlikely to be an issue. I think this was touched on briefly in the recent Scootering article on oils without resolution.
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Post by insideright on Jul 25, 2012 19:57:50 GMT
Cheers lads think were sorted now keep ya updated to anything relevant based on your comments.
Many Thanks
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