Did my motor kerplode? update
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Ossessionato
LX190
Joined: 12 Oct 2007
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Location: New Zealand
Fri Aug 08, 2014 8:46 pm quote
Morgan wrote:
I can't help but say this is gripping. I can't wait to learn the outcome! Super internet awesome recipe cooking up right here.
I suggest it was Mr Piston, in the combustion chamber, with the valve.
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
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Location: Sedgwick, Kansas
Sun Aug 10, 2014 4:01 pm quote
I'm sorry that I haven't been posting more updates but, as I have said I have been busy. I backed off the exahaust valve clearance nuts and as you can see the one in the foreground got loose but the other one in the background that you can't see is still under tension. My current theory is that the head of the valve in the background broke off at the big end and dropped into the cylinder gumming up the works.

What do you think?

IMG_20140810_184711.jpg

MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
Joined: 04 May 2010
Posts: 3902
Location: Sedgwick, Kansas
Sun Aug 10, 2014 4:20 pm quote
Well, there's you're problem.

I took the exhaust cam pivot shaft out and you can see that one of the valve stems came out about a half inch (10 mm ) farther than the other.

I can predict the future.

I am going to take off the head and retrieve the valve end. I am going to call Scooterwest and order parts.

I think I'll sleep better tonight.

IMG_20140810_191050.jpg

Ossessionato
GTS 250 "Audrey"
Joined: 31 May 2008
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Location: New Harbor, Maine
Sun Aug 10, 2014 4:33 pm quote
Sleuth
Great work Matt! The photos are impressive too. Eager for you to get new parts and get it running again. Don't end the story here.
Ossessionato
Joined: 04 Aug 2007
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Location: Austin
Sun Aug 10, 2014 8:02 pm quote
Yep, that'll do it! Let us know if you need any tips during the rebuild!
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
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Location: Sedgwick, Kansas
Sun Aug 10, 2014 11:15 pm quote
OK, now that I'm on the back half of the project I could use some advice on my parts shopping list. I will need an exhaust valve, a head gasket, a cylinder to block gasket and a stator cover gasket. I'm Also thinking that I should replace all the hoses on the motor while I'm in there. Am I forgetting anything? Any other "you might as well" items that I should get?
Ossessionato
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Mon Aug 11, 2014 2:49 am quote
vintage red matthew wrote:
OK, now that I'm on the back half of the project I could use some advice on my parts shopping list. I will need an exhaust valve, a head gasket, a cylinder to block gasket and a stator cover gasket. I'm Also thinking that I should replace all the hoses on the motor while I'm in there. Am I forgetting anything? Any other "you might as well" items that I should get?
If the valve head rattled around in there, this is what you are likely to find. But the spark plug should have been mangled too, so it is still undetermined. Let's hope for the best.

image.jpg
The head. This one lost two valve heads.

IMG_2548.JPG
Looking down. That hole in the piston means junk got in the crankcase too.



Last edited by WLeuthold on Mon Aug 11, 2014 3:38 am; edited 1 time in total
Veni, Vidi, Posti
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Mon Aug 11, 2014 3:26 am quote
vintage red matthew wrote:
OK, now that I'm on the back half of the project I could use some advice on my parts shopping list. I will need an exhaust valve, a head gasket, a cylinder to block gasket and a stator cover gasket. I'm Also thinking that I should replace all the hoses on the motor while I'm in there. Am I forgetting anything? Any other "you might as well" items that I should get?
don't order ANYTHING till you pull it apart fully. Because your just guessing at this point.
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
Joined: 04 May 2010
Posts: 3902
Location: Sedgwick, Kansas
Mon Aug 11, 2014 4:32 am quote
old as dirt wrote:
vintage red matthew wrote:
OK, now that I'm on the back half of the project I could use some advice on my parts shopping list. I will need an exhaust valve, a head gasket, a cylinder to block gasket and a stator cover gasket. I'm Also thinking that I should replace all the hoses on the motor while I'm in there. Am I forgetting anything? Any other "you might as well" items that I should get?
don't order ANYTHING till you pull it apart fully. Because your just guessing at this point.
Of course.
Addicted
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Mon Aug 11, 2014 5:04 am quote
You may need a head and maybe a piston.
Moderaptor
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Mon Aug 11, 2014 6:32 am quote
A few O rings may be needed too.

But wait until the head's off (and maybe the cylinder) before deciding what to do.
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
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Thu Aug 14, 2014 6:53 am quote
Well, there you go. It may be possible to reuse the piston with some dremel work but it looks like the head is nicely toasted. The broken valve head made several divots, one almost 1/4 inch (5mm) deep. One of them distorted the valve seat. It may be possible to replace the seat but I would be afraid of the head cracking or warping at some point down the road. Not shown but the cylinder wall is fine. At some point this motor will probably get the Malossi treatment but until then I will be preparing my spare motor. It came from Max6200 when his scooter caught fire. It is covered in melted plastic and most or all of the electrical components are probably fried. I'm hoping the stator is OK. The internal mechanical parts like the crank, rod, piston and valve train should be OK.

Once, on the not so modern side Vader19 said "Having spare parts is one thing (good), but having a good, running spare motor is really nice.. like having a hard, oily security blanket!"

IMG_20140814_081045.jpg

IMG_20140814_081059.jpg



Last edited by vintage red matthew on Thu Aug 14, 2014 7:13 am; edited 1 time in total
Enthusiast
2001 ET4
Joined: 18 Jul 2014
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Location: Birmingham, AL
Thu Aug 14, 2014 7:03 am quote
Wow, that's rough. But the engine must have stopped fairly quick as there are not more "divots".
How many miles were on this engine?
Veni, Vidi, Posti
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Thu Aug 14, 2014 10:56 am quote
Gripping and...informative indeed.
Addicted
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Thu Aug 14, 2014 7:09 pm quote
Sorry to see this result for your engine, VRM. So far in this thread I see two people having experienced an exhaust valve head come off. Is this a rare kind of engine failure for the Quasar motor?

Anyone care to suggest a cause for this? Are the exhaust valves weak, have stress concentrations at the fracture point, or hard / brittle? Is this possibly a result from a hard life at high rpm? Tight or loose clearance?


Bill
Ossessionato
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Fri Aug 15, 2014 4:41 am quote
Cosmos wrote:
Is this a rare kind of engine failure for the Quasar motor?

Anyone care to suggest a cause for this? Are the exhaust valves weak, have stress concentrations at the fracture point, or hard / brittle? Is this possibly a result from a hard life at high rpm? Tight or loose clearance? Bill
Two engines among our scooter club have had exhaust valves break and get into the combustion chamber. One was a GT, Leader engine, and the other a GTS, Quasar.

As for the questions, There may be a design flaw in the engines. But my GT, 2006 model with 62,000+ miles, at least half of them at highway speeds, still runs reasonably well with the original valves. There are others with higher mileage than mine.

Matthew got off easy with his valve break, as the two in the warehouse both look like the photo I posted above. The engine probably stopped immediately.
Ossessionato
2008 MP3 500, 2013 BV350
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Fri Aug 15, 2014 4:44 am quote
Get a new piston or could will have pinging issue from hot spots on the piston.
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
Joined: 04 May 2010
Posts: 3902
Location: Sedgwick, Kansas
Fri Aug 15, 2014 6:36 am quote
I agree that it needs a new piston and the cylinder will have to be checked for wear and a possible rebore but I'm not going to do that now. As I said I have a spare motor and that is going in. With the repair costs on this top end going up I think I will at some time put on a Malosi head, cylinder and piston. That shouldn't be much more than putting it back stock.

The bike has about 28.000 miles on it. I was traveling about 20 mph when it happened. It was probably turning less than 2000 rpm. All of the damage must have occoured in less than a tenth of a second. I didn't hear anything.
Veni, Vidi, Posti
Joined: 21 Feb 2011
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Fri Aug 15, 2014 12:09 pm quote
Sorry about this man! I think my GT is going to go the same way sometime. I seem to remember a thread of yours about the variator being busted to smitherins. Guess what! My GT variator got a bit shaken up as of recently too. I am hoping that these two may not be related.
Addicted
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Fri Aug 15, 2014 1:11 pm quote
Did you always use premium gas in this engine? The reason I am asking is that there seems to be a lot of carbon in the top end, and premium gas (around here) has extra detergents to prevent carbon buildup. Did the engine consume oil? This could also lead to carbon buildup.

Cheers and thanks,
Bob
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Fri Aug 15, 2014 1:44 pm quote
I found this generalized article on valve failure. Very interesting read.


http://www.aa1car.com/library/ar1192.htm

Bill
Veni, Vidi, Posti
Neutrino MP3 492.7 AK, 2013 Moto Guzzi Norge
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Fri Aug 15, 2014 3:05 pm quote
VRM looks like a fairly cheap repair than would Bill took on his. Having the piston intact and no holes for bits to get into the crank is good.

Replace the head and new piston.
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Fri Aug 15, 2014 7:56 pm quote
while unfortunate, you got off pretty easy with just the top end damage.

snap your spare motor in there and save up your duckets for a gonzo build on that roached motor.

i'd go cyl kit & head, personally. in the mean time, ride till the weather won't let you and slowly build up the other. and when the snow is on the ground, and everything looks bleak.... pour yourself a stiff one and get to work. spring beckons. and you're gonna have a johnny kick ass ride when the frost burns off!

btw, i wanted to say good job on diving right in and getting your hands dirty. forging roads unknown is sometimes the quickest route toward new found knowledge.

just remember, it takes twice as long to put 'em back together as it does to take 'em apart!

-g
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
Joined: 04 May 2010
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Sat Aug 16, 2014 6:40 am quote
greasy125 wrote:
snap your spare motor in there and save up your duckets for a gonzo build on that roached motor.

i'd go cyl kit & head, personally. in the mean time, ride till the weather won't let you and slowly build up the other. and when the snow is on the ground, and everything looks bleak.... pour yourself a stiff one and get to work. spring beckons. and you're gonna have a johnny kick ass ride when the frost burns off!

just remember, it takes twice as long to put 'em back together as it does to take 'em apart!

-g
My thoughts exactly.

Anything other upgrades I should be looking at while I'm buying parts? I don't think that I really need the upgear mod. It bounces off the rev limiter at about 80mph actual and I don't ever need to go faster than that. I could use the extra torque to hold speed in a headwind and/or going uphill.

Greasy, I think you are being wildly optimistic on the ratio of rebuild to teardown time. Especially for someone like me, who has rebuilt motors before but not not modern Vespa motors. I'm thinking more like 10-20:1.

I always used premium gas except for twice when it wasn't available.

Everyone should stay tuned for the rebuild thread. I am going to need plenty of advice.

Matthew
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Sun Aug 17, 2014 2:08 pm quote
Did you ever put anything other than gas in your fuel tank? Additives, stabilizer, injector cleaner, etc?

Last edited by Motovista on Sun Aug 17, 2014 2:37 pm; edited 1 time in total
Addicted
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Sun Aug 17, 2014 2:35 pm quote
Why would you ever put premium fuel in a stock Vespa ?
Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
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Sun Aug 17, 2014 2:56 pm quote
The ET4 manual specifies a minimum octane rating of 90. This calls for premium fuel. Regular/mid-grade are 87/89 in my area. Don't have a GTS 250 manual but suspect it's similar.

Edit: could not find a specification for the GTS250, but the 300 specifies 95 octane. I can't even get 95 around here. So again, premium fuel is the right choice. 11.5:1 compression requires the right fuel.


-Craig
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Sun Aug 17, 2014 3:22 pm quote
Whatever. It certainly does nothing for performance; only inhibits pre-ignition. One of my BMW's specifies 89. In 28000 miles I have only used 87 and a good bit of that has been Pemex. Never a problem.
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Sun Aug 17, 2014 3:46 pm quote
Some manufacturers of small engines recommend premium fuel even if the engines are not high compression. Again, premium fuel has a lot of detergent to stop carbon buildup on pistons, cylinder heads, and behind the rings. It's cheap in the long run, but perhaps not so much if you trade your vehicle or equipment every few years.

Cheers,
Bob
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Sun Aug 17, 2014 4:35 pm quote
Bob Cowley wrote:
Some manufacturers of small engines recommend premium fuel even if the engines are not high compression. Again, premium fuel has a lot of detergent to stop carbon buildup on pistons, cylinder heads, and behind the rings. It's cheap in the long run, but perhaps not so much if you trade your vehicle or equipment every few years.

Cheers,
Bob
This is from Edmunds.com
Drivers used to buy a tank of premium gas every once in a while to clean their engine. Years ago, premium gasoline contained more detergents and additives to stop carbon deposits. But experts say that because of government regulations aimed at cutting emissions, all grades of gas, including those you buy at independent, low-price stations have plenty of additives to both protect engines and cut pollution.

Last edited by acejones on Sun Aug 17, 2014 4:43 pm; edited 1 time in total
Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
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Sun Aug 17, 2014 4:36 pm quote
acejones wrote:
Whatever. It certainly does nothing for performance; only inhibits pre-ignition. One of my BMW's specifies 89. In 28000 miles I have only used 87 and a good bit of that has been Pemex. Never a problem.
YES! It prevents pre-ignition... Which can destroy your motor! Your BMW has a knock sensor that will adjust your timing to accommodate lower octane fuel. Your Vespa does not. I'm not going to treat my motor that way.

-Craig
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Sun Aug 17, 2014 4:45 pm quote
caschnd1 wrote:
acejones wrote:
Whatever. It certainly does nothing for performance; only inhibits pre-ignition. One of my BMW's specifies 89. In 28000 miles I have only used 87 and a good bit of that has been Pemex. Never a problem.
YES! It prevents pre-ignition... Which can destroy your motor! Your BMW has a knock sensor that will adjust your timing to accommodate lower octane fuel. Your Vespa does not. I'm not going to treat my motor that way.

-Craig
Maybe Vespa should have put knock sensors on these systems. After all, they sell these scooters all over the world and premium is pretty rare in a lot of the world.
Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
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Sun Aug 17, 2014 4:53 pm quote
The point is they don't currently have it. This is why you should use premium fuel whenever possible.

-Craig
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Sun Aug 17, 2014 5:21 pm quote
Thanks for the "advice". In over 50 years of driving a multitude of vehicles 30000 miles a year, I've never had an engine failure on any vehicle and that's burning all kinds of fuel from all kinds of sources and that includes stuff sourced out of a metal drum and filtered through a shop towel. I suspect most owners manuals are written by lawyers, not engineers.
Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: 27 Oct 2009
Posts: 4434
Location: Chandler, Arizona, USA
Sun Aug 17, 2014 6:16 pm quote
I'm an engineer, not a lawyer. I have seen pre-ignition damage first hand in my own engines. It's pretty ugly. In order to get the power from these small engines they boost up the compression. This makes you even more vulnerable to potential problems. In most cases you are right, it doesn't matter much. But it's just not worth having to rebuild a motor if things go bad.

This is pre-ignition damage in a 80" Harley motor. The top of the piston was hammered so hard it collapsed on the rings.

Ossessionato
2008 MP3 500, 2013 BV350
Joined: 13 Oct 2012
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Location: Va.
Tue Oct 20, 2015 5:29 am quote
acejones wrote:
caschnd1 wrote:
acejones wrote:
Whatever. It certainly does nothing for performance; only inhibits pre-ignition. One of my BMW's specifies 89. In 28000 miles I have only used 87 and a good bit of that has been Pemex. Never a problem.
YES! It prevents pre-ignition... Which can destroy your motor! Your BMW has a knock sensor that will adjust your timing to accommodate lower octane fuel. Your Vespa does not. I'm not going to treat my motor that way.

-Craig
Maybe Vespa should have put knock sensors on these systems. After all, they sell these scooters all over the world and premium is pretty rare in a lot of the world.
But 95 RON Octane (=91 (R+M)/2) is the Regular fuel in most of the world too, so it's not an issue.
Ossessionato
2008 MP3 500, 2013 BV350
Joined: 13 Oct 2012
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Location: Va.
Tue Oct 20, 2015 5:37 am quote
acejones wrote:
Whatever. It certainly does nothing for performance; only inhibits pre-ignition. One of my BMW's specifies 89. In 28000 miles I have only used 87 and a good bit of that has been Pemex. Never a problem.
I laugh that you think 28,000 miles would be enough to have a problem. Don't worry, every tank you run 87 you are helping to put a nice hole in your piston.

Can't figure people like you out, you spend top dollar on one of the most expensive rides you can find (BMW & Vespa) then you put cheap gas with octane rating lower than the manufacture recommends in them.
Veni, Vidi, Posti
2007 LX 150
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Tue Oct 20, 2015 6:15 am quote
People will argue over diet, health issues, motor oil and gas.

"I have eaten a pound of bacon every day for 20 years without any problems."

"I have smoked 2 packs of cigarettes for 30 years and never been sick a day in my life."

"I have used XYZ oil in all my vehicles and never had a breakdown."

"I have run cat piss in my Vespa for 30,00 miles without a problem."

The truth is that undesirable effects don't follow a definite timetable, so people sometimes claim success by saying nothing has happened to them so far, so all is well and good with what they are doing. Of course, there are always exceptions, but the odds are greater that pushing the envelope can bite you in the ass. Even Russian Roulette can be safe five times in a row.
MV Santa
GTS250, 1960 VBA, 1975 VBC, 1980 P200E cutdown
Joined: 04 May 2010
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Location: Sedgwick, Kansas
Tue Oct 20, 2015 6:25 am quote
I wasn't sure why my thread got new responses then I saw that it had morphed into another octane debate. That's OK but looking back at I realized that I never updated how things came out.

Long story short it could not have worked out better. I put my spare motor in after transferring all the components from my motor for ones that had been damaged in the fire. It started right up and is still running fine.

My plan for the original motor was to buy a Malossi head/cylinder kit reinstall it and sell the other motor. I bought a 4V head from another member that had never been installed and I was getting ready to order the cylinder when another member, local to me, Eyeball Bill had the lower end go out on his GTS. He was faced with a $4000 repair estimate and did not have the mechanical ability to fix it himself so he sold the bike to me for $400 and bought a Yamaha Majesty. The bottom end on my motor was good and the head/cylinder was good on his. I took the top off of his motor and put it on mine and put the assembly back into his body and I had another working scooter that I sold for $2400 on eBay. I also sold the Malossi head for the same price I bought it for.
World Traveler
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Tue Oct 20, 2015 7:35 am quote
Awesome MATT. good job.
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