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Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
Joined: UTC
Posts: 8926 Location: Ashburn, Va. Home to the Internet |
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Most have only been 2008 for a short period. There was a bad batch of pistons that caused it.
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Maksor wrote: several causes not only a bad batch thats only sold in the USA it seems Curious what other causes you'd attribute to broken piston lands. |
Ossessionato
2009 MP3/250, 2012 GTS Super 300ie
Joined: UTC
Posts: 4308 Location: Marietta, GA |
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WEB-Tech wrote: Most have only been 2008 for a short period. There was a bad batch of pistons that caused it. I am not as knowledgeable as others here, but when it comes to the 500 Engine, but I think it is a "Bad Design". They should have left the Master Engine at 400cc where there seems to be less of a problem. Keith, Marietta, GA |
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Keith: You and I have 500s made in March 2015 and threw oil during breaking-in. We did the Rule of 5 and the problem vanished for both of us.
Isn't that just another mp3 500 quirk that we overcame thousands of miles ago? |
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I read a whole bunch of posts on MV, and I'm not entirely sure that the bad batch of pistons is the sole cause. Although there did seem to be a preponderance of oil-in-the-airbox during that time, it may have been partly due to the fact that most of the 500's of that era were made during that time. They *did* change part numbers after that, indicating a change of vendor or design. But here my speculation about the true and main cause:
Bad engineering. There just isn't enough metal between the two rings for the forces applied to it. The 400 piston, and even the 460 piston have a wider land. The 493 has a thin land that has been undercut, and it just isn't strong enough. Maybe it's OK for a while, but there's a reason they don't make springs from aluminum- it has a finite fatigue life. All the pistons I've seen in pictures have the land broken in exactly the same position on the piston- at the top between about 10 o'clock and 2 o'clock. That says bad engineering to me. European sources (anecdotally) point to a lack of lubrication on the cylinder from the oil pressure being too low when the oil is hot, which puts too much strain on the rings. Thus a recommendation to use 50-weight oil and not run the engine all-out. They came to the same conclusion as Klaborde independently. As far as I know, they still make the 493 Master engine. They don't make the 400 or the 460. Piaggio must think that it's not enough of a problem that they need to do a massive redesign. If it were me, I'd move that top ring up by 2 mm to thicken that land. I wouldn't buy one of those cast-iron aftermarket pistons since the clearance is too small. |
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni, 2008 Vespa S150
Joined: UTC
Posts: 8926 Location: Ashburn, Va. Home to the Internet |
UTC
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Squeazel,
Then why doesn't the 400 have the same problem? Would think the ring spacing would be the same. |
Ossessionato
2009 MP3/250, 2012 GTS Super 300ie
Joined: UTC
Posts: 4308 Location: Marietta, GA |
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jfolander wrote: Keith: You and I have 500s made in March 2015 and threw oil during breaking-in. We did the Rule of 5 and the problem vanished for both of us. Isn't that just another mp3 500 quirk that we overcame thousands of miles ago? The solution we are both using seems to be working. I just wish I didn't have a "Quirk" to deal with... Keith, Marietta, GA |
Ossessionato
2009 MP3/250, 2012 GTS Super 300ie
Joined: UTC
Posts: 4308 Location: Marietta, GA |
UTC
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Squeazel wrote: I read a whole bunch of posts on MV, and I'm not entirely sure that the bad batch of pistons is the sole cause. Although there did seem to be a preponderance of oil-in-the-airbox during that time, it may have been partly due to the fact that most of the 500's of that era were made during that time. They *did* change part numbers after that, indicating a change of vendor or design. But here my speculation about the true and main cause: Bad engineering. There just isn't enough metal between the two rings for the forces applied to it. The 400 piston, and even the 460 piston have a wider land. The 493 has a thin land that has been undercut, and it just isn't strong enough. Maybe it's OK for a while, but there's a reason they don't make springs from aluminum- it has a finite fatigue life. All the pistons I've seen in pictures have the land broken in exactly the same position on the piston- at the top between about 10 o'clock and 2 o'clock. That says bad engineering to me. European sources (anecdotally) point to a lack of lubrication on the cylinder from the oil pressure being too low when the oil is hot, which puts too much strain on the rings. Thus a recommendation to use 50-weight oil and not run the engine all-out. They came to the same conclusion as Klaborde independently. As far as I know, they still make the 493 Master engine. They don't make the 400 or the 460. Piaggio must think that it's not enough of a problem that they need to do a massive redesign. If it were me, I'd move that top ring up by 2 mm to thicken that land. I wouldn't buy one of those cast-iron aftermarket pistons since the clearance is too small. That's why I think the note I have in my Signature Line is keeping those of us following those rules without issue... Yet??? In time, we will probably have it. Keith, Marietta, GA |
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The problem is not exclusively about American MP3s.....
2015 seems to be a very bad year for ABS models |
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Squeazel wrote: European sources (anecdotally) point to a lack of lubrication on the cylinder from the oil pressure being too low when the oil is hot, which puts too much strain on the rings. Thus a recommendation to use 50-weight oil and not run the engine all-out. They came to the same conclusion as Klaborde independently. Probably the temperatures are softer in Marietta than in Paris |
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crock wrote: How fast are you going at 5000 RPM? |
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WEB-Tech wrote: Squeazel, Then why doesn't the 400 have the same problem? Would think the ring spacing would be the same. sheet metal to make it stiffer). A tiny bit less flexing may be enough to change a 10,000 mile problem into a 200,000 mile problem, in other words, from a problem into a non-issue. Or is could be slightly thicker or it could be made from a slightly different alloy. Either way, it doesn't take much. |
UTC
Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2013 Piaggio BV 350, 2014 Can Am Spyder RT
Joined: UTC
Posts: 7542 Location: Madison, Wisconsin |
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Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2013 Piaggio BV 350, 2014 Can Am Spyder RT
Joined: UTC
Posts: 7542 Location: Madison, Wisconsin |
UTC
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Squeazel wrote: WEB-Tech wrote: Squeazel, Then why doesn't the 400 have the same problem? Would think the ring spacing would be the same. sheet metal to make it stiffer). A tiny bit less flexing may be enough to change a 10,000 mile problem into a 200,000 mile problem, in other words, from a problem into a non-issue. Or is could be slightly thicker or it could be made from a slightly different alloy. Either way, it doesn't take much. Oh my lord, stop at 'speculate'. |
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Loulou i get a lot of frence importered scooters to repair those aren't well take care off in fr belt well over due, oil as black as a schoolbord
malossi weights without the platic covers on them, clutches with a kg of dust in them and so on and not speaking about the covers And i drive also in france and most of them go Full throttle spliting lanes with on of mode on the throttle seems all the time in paris |
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Maksor wrote: And i drive also in france |
Enthusiast
2009 Piaggio MP3 500ie
Joined: UTC
Posts: 58 Location: Parts Unknown, California, USA |
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Well, I just went out and checked my production date... 07/08. Knowing that I need to identify whether my piston is an A, B, or C, are there any recommendations for specifics on what I should get? That is to say, if there's any particular brand from any particular store I should get? Getting tired of draining my air cleaner on the reg.
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As far as A, B, C or D goes, it will be marked on the top of the piston. If you have an endoscope, you might be able to see it- a letter stamped right in the middle of the crown of the piston. At the same time you can see if the cylinder is scored, which would make the piston mark irrelevant- the piston is fitted to the cylinder to 5/10000 of an inch (thus the different A,B,C piston diameters) and a scratched cylinder is a junk cylinder. Coated aluminum cylinders are long-lasting until the coating is compromised. An endoscope adequate for the job can be purchased from Amazon for <$20.
If you have the time then just skip the endoscope and take it apart, see what needs replacement (you might just need rings, but I'd replace the entire piston if so- it's only $50 more) then order the parts from AF1; they'll take a week to get there- have a refreshing beverage or 6 while you're waiting. If you replace just the piston, match the letter to the one on the top of the crown. As far as part numbers go, xxxxxx0001 is "A", xxxxxx0002 is "B" etc. I didn't do this, but some people say you should break the glaze on the cylinder with a few passes of a ball-hone to get the rings to seat sooner. 30 seconds is all you should do; you don't want to damage the Nikasil coating. Make sure to test your reed valve, too. Suck on the hose to the air filter and it should go "meep", blow on it and it should do nothing. |
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