OP
UTC

Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
 
Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
UTC quote
On my way home from the bank, the bike loses all power, makes a loud exhaust noise. I coast to the side of the road and try to get it to restart, but no luck. The engine spins freely, as if there was no compression. Fortunately, this happened about a mile from home, so I push the scooter. (Actually a couple of folks stopped to see if I needed help, which was nice!)

I check out the bike in my garage and the spark plug slips out of its hole. The threaded are filled with traces of the head, so the hole it definitely stripped. The bike is about a year old, with 2k on it, so the plug is original.

Any advice as to (1) why this happened and (2) the best way to fix it? My guess is that it was overtightened or cross threaded at the factory and just gave out now. Does someone sell an insert to repair the threads? A new head seems like an expensive fix. Has anyone tried to drill out the hole and tap it for a larger diameter plug? (Like the one on my 10 year old, $100 lawnmower that has never been changed or given me problems!)

I am frustrated, but also happy that it did not happen at the top of Mt. Hamilton a few weeks ago. Advice is appreciated!
@boulty avatar
UTC

Moderator Australis
2014 Moto Guzzi V7 Stone, 2014 Vespa 150 Primavera (sold) 2003 Vespa GT200 (sold)
Joined: UTC
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Location: New Zealand where it is already tomorrow..
 
Moderator Australis
@boulty avatar
2014 Moto Guzzi V7 Stone, 2014 Vespa 150 Primavera (sold) 2003 Vespa GT200 (sold)
Joined: UTC
Posts: 5654
Location: New Zealand where it is already tomorrow..
UTC quote
Ouch! Not good at all, my sympathy to you.
I am sure others will attend with the exact spec but I am sure this has been covered on the forum before, though not often. Have a browse on the Search facility and see what you find.
From my general engineering knowledge these situations can be remidied by a 'Helicoil' kit...but I am unsure of a version for a Piaggio engine.

Good luck.
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Posts: 15080
Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 15080
Location: The state of insanity, SoCal
UTC quote
your best best is to find a used head and just R&R the whole unit.

you'd have to have a custom helicoil/recoil made for it if you wanted to go that route.

drilling out and rethreading to a larger size isn't really an option. there isn't enough meat on the head to make that safe.

best,
-greasy
@theoz avatar
UTC

Sir Frets-A-Lot
Vespa GT250ie/L, Honda Ruckus 50, Honda NT700V, Honda CB125
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Location: Bee eff eee.
 
Sir Frets-A-Lot
@theoz avatar
Vespa GT250ie/L, Honda Ruckus 50, Honda NT700V, Honda CB125
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Posts: 11197
Location: Bee eff eee.
UTC quote
greasy125 wrote:
your best best is to find a used head and just R&R the whole unit.

you'd have to have a custom helicoil/recoil made for it if you wanted to go that route.

drilling out and rethreading to a larger size isn't really an option. there isn't enough meat on the head to make that safe.

best,
-greasy
time-Serts are ok too.

Helicoil, Rolf won't trust them.
@theoz avatar
UTC

Sir Frets-A-Lot
Vespa GT250ie/L, Honda Ruckus 50, Honda NT700V, Honda CB125
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Sir Frets-A-Lot
@theoz avatar
Vespa GT250ie/L, Honda Ruckus 50, Honda NT700V, Honda CB125
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Posts: 11197
Location: Bee eff eee.
UTC quote
A head is expensive new btw. Like $430 or something.
@ctl73 avatar
UTC

Hooked
GT-200
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Location: PA
 
Hooked
@ctl73 avatar
GT-200
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Location: PA
UTC quote
Dude that is the worst. I would say the most likely cause is the plug was not tightned to spec at some point. I have seen this many times after service when tech's leave plugs loose. There may be a heli-coil out there that will repair it but it won't be an off the shelf item. Contact a local machine shop they heli-coil every day. I don't know how tight the spot is to get at but unless it is a straight shot you won't be fixing it on the bike. Never mind what bits will get in the combustion chamber. My advice don't try to mickey it pull the head or have it pulled. Your best bet is to bring the head to a first class machine shop. The cylinder head can be repaired but at what cost. You may need to replace the head and eather way the head should be off. I would love to do a job like that do you live near PA. Good luck and sorry for your loss.
Chris
@greasy125 avatar
UTC

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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Location: The state of insanity, SoCal
UTC quote
TheO.Z. wrote:
greasy125 wrote:
your best best is to find a used head and just R&R the whole unit.

you'd have to have a custom helicoil/recoil made for it if you wanted to go that route.

drilling out and rethreading to a larger size isn't really an option. there isn't enough meat on the head to make that safe.

best,
-greasy
time-Serts are ok too.

Helicoil, Rolf won't trust them.
for bolt holes, yes, time-serts are the way to go. unfortunately, sometimes you can only get a helicoil in.

the spark plug helicoils i've used have always worked well.
but, not really an option in this situation. which sucks, no matter how you look at it.

a steep repair bill in the near future...

best,
-greasy
@lothar avatar
UTC

Addicted
Vespa GT 200L
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Location: Vista, CA
 
Addicted
@lothar avatar
Vespa GT 200L
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Location: Vista, CA
UTC quote
I think this is a warranty issue. Take it to the dealer, especially with you low millage! When I purchased my GT 200 last year, it came with two year warranty., but then later they had a promo and added another year.

There would be no reason for you to change the plug with such low miles on the GT 200, so I think you should make a stink. If the dealer does not listen, contact Piaggio direct!

Lothar
@ctl73 avatar
UTC

Hooked
GT-200
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Location: PA
 
Hooked
@ctl73 avatar
GT-200
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Location: PA
UTC quote
So true if you know you never removed the plug I try to get it covered. If that was my bike and I never touched it I would be bitching up a storm.
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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UTC quote
If the plug hasn't been changed in over two years of ownership the services haven't been done properly *by the book*. I'm not saying the 'book' is correct mind.

So the plug has propably been changed by someone sometime?
@harvey avatar
UTC

Ossessionato
2016 Honda NC750XD, 2007 GTS (sold),
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Location: Canada
 
Ossessionato
@harvey avatar
2016 Honda NC750XD, 2007 GTS (sold),
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Location: Canada
UTC quote
If the bike was purchased a year ago- even if it was an '2007 model', then it's still within the recommended maintenance interval for spark plugs of 12,000 kms or 2 years.

It's definitely worth trying for a warranty claim.

Good luck!

Harvey
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UTC

Addicted
2009 Vespa GTS Super duper pooper scooper
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Location: Tuscaloosa, Alabama
 
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@trowel_and_cuffs avatar
2009 Vespa GTS Super duper pooper scooper
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Location: Tuscaloosa, Alabama
UTC quote
i would carry it to your local dealer and have them look at it. them cylinder is in a tight spot. the head may just need to be replaced i personally wouldn't heli-coil it. may cruise online and find a wrecked 200 for engine parts.
UTC

Hooked
Joined: UTC
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Hooked
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UTC quote
'Helicoil' kits are a stop-gap fix. Your best bet is, unfortunately, another head. By-the-way. I feel it's a good idea, when dealing with aluminum head motors, to remove the spark plug, at about it's half-life, inspect it, check the gap, then reinstall it with a dab of antisieze. This will keep the plug from welding itself (so to speak) to the head.
OP
UTC

Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
 
Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
UTC quote
I have the same theory about the plug not being completely tightened after looking at it closer. The threads are galled in only part of the threaded portion, which leads me to think it wiggled around for a while. If it were cross threaded, I would not expect it to give out spuriously.

I will press on the dealer to see if they will fix it, but I am not particularly hopeful. I am not a fan of Helicoil, but I suppose if that is the only option, it might be worth considering. Seems like back in the day when I worked on air cooled VW's, they had inserts specially made for this scenario. Of course, there were probably 100x as many VW's around as Vespas. Sadly pulling the head is required, which is just sort of a PITA. I can find a machine shop to do the work, it is just a question of deciding what to do, and am hoping someone has already found and worked out a solution.

$400 for a new head? That will be the last resort.

Fortunately, this is an extra vehicle (although one I use a fair bit), so it is not a pressing issue to fix. And I am headed to Kauai tomorrow for a week's vacation with the wife, so have some time to consider some options. Time to check out McMaster Carr!
@jcwhitney avatar
UTC

Hooked
Lambretta SX, Stella, Honda
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Location: USA
 
Hooked
@jcwhitney avatar
Lambretta SX, Stella, Honda
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Location: USA
UTC quote
Buy a new Spark Plug, gap it, put anti-sieze on the threads and screw it in as far as you can by hand.
Once it is screwed in by hand as far as it will go, torque to proper specs and ride on.
Make sure you catch some threads before you put the ratchet to it.
If it won't go in a few turns by hand have someone else try, if that fails you may indeed have a problem.
Best $8 experiment you'll ever perform.
Doubtful the Cylinder Head is/was stripped from the factory.
If the plug "fell out" of it's own accord the Scooter must have been running poorly (low compression) for some time prior to the latest event.
@theoz avatar
UTC

Sir Frets-A-Lot
Vespa GT250ie/L, Honda Ruckus 50, Honda NT700V, Honda CB125
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Posts: 11197
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Sir Frets-A-Lot
@theoz avatar
Vespa GT250ie/L, Honda Ruckus 50, Honda NT700V, Honda CB125
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Location: Bee eff eee.
UTC quote
I've had the head of a GT time serted and it was fine. They make the inserts in the right size.

You're in the bay area? I have a guy you can call - but I have to track down his info. If I can I'll give it to you. Former owner of Mission Motorcycles, but he does his work out of Rhonert Park now. I think his first name is Dan?
@ufo avatar
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Molto Verboso
MP3 250
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Location: San Diego
 
Molto Verboso
@ufo avatar
MP3 250
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Location: San Diego
UTC quote
Exact same thing happened 2 me. Now I don't feel like the lone ranger.. Laughing emoticon
Forum member supplied image with no explanatory text
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Posts: 44567
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44567
Location: Pleasant Hill, CA
UTC quote
My guess (but who knows what the truth is) is that there are enough good threads left inside to do the job intended. I'd try j.c.whitney's advice for starters before getting too despondent.
OP
UTC

Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
 
Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
UTC quote
Inserts
I am thinking of giving these a try. It seems like a reasonable approach, and these guys say enough about how their product works to give me impression that they know what they are doing. Anyone have experience with them? It would be great to find a place that can do this work for me, since tapping a clean hole is not the easiest thing to do, and I hate to monkey with it on a $400 head...

www.fulltorque.com
⬆️    About 2 months elapsed    ⬇️
OP
UTC

Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
 
Enthusiast
'07 GT200
Joined: UTC
Posts: 82
Location: Orange County, CA
UTC quote
Scooter is back!
Okay, after talking with the dealer and an independent shop, I ended up going with the independent. It is possible to put in an insert and we did it the right way, pull the head and send it to a machine shop. Total outlay was just north of $300, and that includes new oil and coolant. Other than missing the last bit of the summer, it was not as painful as I was expecting. It's good to have it back!
⬆️    About 1 year elapsed    ⬇️
@chiorpheus avatar
UTC

Member
GT200 - Vintage Green
Joined: UTC
Posts: 11
Location: Chicago, IL
 
Member
@chiorpheus avatar
GT200 - Vintage Green
Joined: UTC
Posts: 11
Location: Chicago, IL
UTC quote
Similar troubles, mechanic says spark plug "blew out&qu
I'm in a somewhat similar spot. My GT200 was cutting out at full throttle, losing power, and once, it completely died. I was able to start it again, but it got harder and harder to start over the course of a week. I thought I could milk out one last week of autumn before putting her in for surgery, but one day, I went out to ride to work, and she wouldn't start.
I'm not lucky enough to have garage space, so while I'd love to try to figure this out myself, opening her up while parked on a busy Chicago street isn't my idea of fun.
So, to the shop she went ... mechanic now tells me the spark plug blew out, there are no usable threads left, and I need a whole new cylinder head, which he quotes at $680 for the part alone.
I see I could get a whole cylinder kit from Malossi for way less than that, and maybe gain some performance. Or I could just get the head off eBay for even less.
How did your guy fix your existing head? Was it a reliable fix? Do you have a phone number? Any other advice?
Thanks, guys.

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