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Piaggio BV250
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Location: Roseburg OR
 
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Piaggio BV250
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Location: Roseburg OR
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So I finally resolved the check engine light issue on my BV250 tourer and thought I would share. Turns out it was a vacuum leak caused by a manufacturing defect which likely exists in all 250/300 engines, and may exist in others as well. I removed the throttle assembly from the intake manifold and discovered that the throttle casting spigot that inserts into the rubber boot on the intake manifold was a casting and had never been machined smooth at the factory so the mold lines left two channels in the spigot for air to leak through. Apparently the factory assumes the rubber boot is soft enough to seal this, but in my case it did not. About a half hour with a file and sandpaper and I had the mold lines removed down to a smooth surface, and after reassembly no more check engine light. This is not the only place this is a problem, as it also exists on the water pump spigots where the hoses clamp on. Unfinished mold lines are there as well and will eventually cause leaks. The solution to that is also to remove the pump and clean up the castings so they are a smooth surface and the hose can seal against them. I have to say as much as I like the design and engineering of Italian machinery, this is something you would never see on a Japanese machine and Piaggio should be embarassed by this. My recommendation to everyone is to repair the water pump as soon as possible, and think about repairing the throttle body when you have a chance. Certainly if you suspect a vacuum leak I would look at the throttle body casting early on in diagnosing the problem.
@berto avatar
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Molto Verboso
2006 LX150 (carbed) | 2007 GT200
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Molto Verboso
@berto avatar
2006 LX150 (carbed) | 2007 GT200
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Location: Toronto
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Thanks for sharing!

Si your bike always had a check engine light before? And it resolved right away after this cleanup?

I don't suppose you took any photos?
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Addicted
'07 GTS250ie "Mechanical Squirrel", '66 Honda Benly, '19 Suzuki 250 cafe "Mouse", '42 Henschel PzKw VI Tiger
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Location: somewhere deep in the back of the garage...Burlington ONT.
 
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@fritz_katzenjammer avatar
'07 GTS250ie "Mechanical Squirrel", '66 Honda Benly, '19 Suzuki 250 cafe "Mouse", '42 Henschel PzKw VI Tiger
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Location: somewhere deep in the back of the garage...Burlington ONT.
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I am for the most part quite impressed with the design and quality of my GTS, but I must admit that I have run into some really dopey details and the occasional outright silly cost cuttings on it.

Having said that, in all the stuff I've owned or worked on, I've not encountered a machine built to the same level of quality since I last worked on a /2 BMW. The Vespa isn't as good as the old Munich built BMWs, but it comes closer than just about anything else I've encountered.

And I would definitely put it ahead of the last late model BMW I examined.
@dooglas avatar
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Veni, Vidi, Posti
GTS 300ABS, Buddy 125, Buddy Kick 125
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Location: Oregon City, OR
 
Veni, Vidi, Posti
@dooglas avatar
GTS 300ABS, Buddy 125, Buddy Kick 125
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So you are saying that there is a casting defect which could cause thousands or tens of thousands of Piaggio 250s and 300s to throw a check engine code related to fuel/air mixture. You didn't say which code was produced, but I might make the observation that actual events as you describe appear to be quite rare among owners of 250s and 300s (I have owned 4).
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Petty Tyrant
0:7 And counting
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Petty Tyrant
@jess avatar
0:7 And counting
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Location: Bay Area, California
UTC quote
gbony wrote:
a manufacturing defect which likely exists in all 250/300 engines
This doesn't pass the blush test, sorry.
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Member
Piaggio BV250
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Location: Roseburg OR
 
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Piaggio BV250
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Location: Roseburg OR
UTC quote
Bought the scooter used (for a good price) and found out why when the check engine light came on during every ride, although it appeared to run fine. Dealer is 3 hours away so I never got the scooter there to read any codes. Checking for vacuum leaks was the final step before hauling it to the dealer, and yes, since cleaning up the throttle body casting the check engine light has stayed off. Not saying every Vespa or Piaggio is running around with vacuum leaks, but I am saying there is a potential for it and this is a place to look if that is a suspected problem. I have had 2 previous BV 250s that ran fine with no check engine light. Those 2 previous BV 250s and the most recent one all had the casting lines on the water pump and were seeping coolant from there.
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Veni, Vidi, Posti
LX190 Friday afternoon special, [s]Primavera[/s], S50, too many pushbikes
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@znomit avatar
LX190 Friday afternoon special, [s]Primavera[/s], S50, too many pushbikes
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You might want to take apart the air filter and see if there's a missing enter key stuck in there.
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Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
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UTC quote
I think that I just laughed so hard I snorted.

your anecdotal evidence is from a pool of... checks notes... three.

okay, that totally pens out.
UTC

Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
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Location: East Anglia, UK
 
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
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Posts: 3766
Location: East Anglia, UK
UTC quote
gbony wrote:
So I finally resolved the check engine light issue on my BV250 tourer and thought I would share. Turns out it was a vacuum leak caused by a manufacturing defect which likely exists in all 250/300 engines, and may exist in others as well. I removed the throttle assembly from the intake manifold and discovered that the throttle casting spigot that inserts into the rubber boot on the intake manifold was a casting and had never been machined smooth at the factory so the mold lines left two channels in the spigot for air to leak through. Apparently the factory assumes the rubber boot is soft enough to seal this, but in my case it did not. About a half hour with a file and sandpaper and I had the mold lines removed down to a smooth surface, and after reassembly no more check engine light. This is not the only place this is a problem, as it also exists on the water pump spigots where the hoses clamp on. Unfinished mold lines are there as well and will eventually cause leaks. The solution to that is also to remove the pump and clean up the castings so they are a smooth surface and the hose can seal against them. I have to say as much as I like the design and engineering of Italian machinery, this is something you would never see on a Japanese machine and Piaggio should be embarassed by this. My recommendation to everyone is to repair the water pump as soon as possible, and think about repairing the throttle body when you have a chance. Certainly if you suspect a vacuum leak I would look at the throttle body casting early on in diagnosing the problem.
Well, this may surprise you but the castings are supposed to be rough finished. That includes the water pump inlet/outlets too. My Suzukis and Hondas were the same. You don't want those shaking loose. It is designed that way to prevent the hose from coming loose. It's unfortunate you had an air leak though. I suspect your casting was a little too rough and hadn't been finished quite right. You assertion that it will likely cause wide scale issues isn't born out by the facts. In the near 20 years the GT/GTS ranges of bikes have been on the road it's not something that has ever been an issue. Well done for spotting your problem and posting about it though.
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Veni, Vidi, Posti
In garage: Yamaha Tricity 155 Urban 2019 - MV Agusta 125 RS 1956
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Location: Latina (Italy)
 
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@attila avatar
In garage: Yamaha Tricity 155 Urban 2019 - MV Agusta 125 RS 1956
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Posts: 8291
Location: Latina (Italy)
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You are probably all right on all, "casting residues" (materozze in italian) are common on objects cast in metal or plastic and it can happen that in mass production some are greater ...
OP
UTC

Member
Piaggio BV250
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Posts: 9
Location: Roseburg OR
 
Member
Piaggio BV250
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Location: Roseburg OR
UTC quote
The problem is not the rough casting. The problem, at least on my scooter, was that the casting molds were offset by about a 1/16th of an inch. Should have got a pic, but was more interested in fixing it. The effect is as if the spigot was cut down the middle and the two halves reassembled offset by about a 1/16th of an inch. This leaves two right angle channels that will be difficult to seal with a rubber boot and are prone to leaking. Maybe I just got lucky and have the only scooter this ever happened to, but I doubt it. I do know that this existed on the water pumps of three out of three BV 250s I have owned. I am a huge fan of Italian motorcycles and in addition to the BV 250s I have also owned two Ducatis, an Aprilia Mana 850, and a Moto Guzzi. I never saw anything like this on any of them. Maybe there was a limited run of these castings and it has since been repaired. I do know there have been multiple reports of leaks where the hoses connect to water pumps of BV 350s and I suspect they may have had the same thing going on.
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Hooked
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Hooked
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UTC quote
I have a BV350 that had some leakage at the water pump. Just like the scores of others who've had that issue, replacing the factory otiker clamp with a worm clamp fixed the issue.
@greasy125 avatar
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Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
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Location: The state of insanity, SoCal
UTC quote
It's because the BV250 is like the little brother to the vespa 250. It gets all the hand me downs and crap that's not good enough for the vespa.

Also, you are not making your case any stronger by shrinking the anecdotal evidence nor by listing what you've owned. That be apples and oranges, my good sir.

You bought a used scooter and it leaks. BFD. fix it and move on. It's not some great conspiracy theory.

Your sample size is three. Calm down.
OP
UTC

Member
Piaggio BV250
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Posts: 9
Location: Roseburg OR
 
Member
Piaggio BV250
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Location: Roseburg OR
UTC quote
No conspiracy theory, just reporting what I found in the hopes it may help someone else who has similar problems. I am done here.
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