Stella carb question: What's your opinion?

racerx1 · Post by **racerx1** » Sun Jul 08, 2012 4:32 pm

I seek opinions from all mechanics with project bikes. I have owned a 2005 2T Stella (used, Craigslist) for 2 months and it has been the worst experience of my life (title issues, reg, orientation, etc.), but I'll try to keep this to one repair issue.

Purchased with 1500 miles on it, it crank started fine for a month. I noticed the injection oil site glass showed the warning float indicating low oil so I added a quart the first week. No change. I added a second quart two weeks later. No change. Both a local dealer & myself figured it was just "stuck". Anyway, after another 200 miles, I noticed the kick start was not as effective as it used to be. Can you see where this is going?

I thought a tune up would be prudent. A scooter mechanic with 20 years experience (none with a Stella) at the dealer showed me a hole in the carburetor where a .05$ plug was missing. I don't know when this plug fell out, but the added oil was escaping through this hole, coating the engine & not lubricating the pistons for some time.

You got it. Combustion pressure had dropped to 70 psi, half of what it should be, due to damaged pistons & rings. Par for the course with this cursed purchase.

Anyway, in your opinion, would replacing the pistons & rings be the only issue or have I caused engine damage beyond these parts? The cost is 2X $103 for pistons, 2x $21 for the rings & hopefully just 3-5 hours for labor (approx $240 @ $60 an hour). I can eat this $500 if you think it will solve the issue.

Despite the mechanic having to "learn the Stella" on the clock, I actually like & trust him. The 1 hr consult was free & he said he wasn't even looking for the work (didn't want to charge someone for his "learning" time). I gave him the 117 page service manual (explode engine view attached). Of course, I would have sold this "as is" but I need to fix this so the sidecar I own won't be wasted, too.

Good Lord, all I wanted was a retro scooter for my son. Thoughts?

BuddyRaton · Post by **BuddyRaton** » Sun Jul 08, 2012 5:47 pm

First off...welcome to MB and the world of "classic" scooters!

Ok lets start at the beginning. There is not an oil "float" it is a simple sight glass.

How many miles have you ridden it?

I'm trying to figure what"plug" could be missing from the carb to disable the oil injector system. The injector system is pretty bullet proof. Can you post a photo of what was missing?

If you dumped 2 quarts into the oil reservoir and didn't see any difference in the sight glass...well...it went somewhere! Possibly a cracked oil reservoir letting it leak out under the tank.

Not sure I understand the "2X $103 for pistons"

You may be able to have the jug bored and go first over sized piston.

It sounds like you were getting some oil since it didn't totally seize. BUT if you were running without or with little oil there is a lot more potential damage than the top end. The oil also lubricates the clutch and fly side bearings and the crank big and little bearings.

3-5 hours labor is waaaaaayyyyy too much for a top end swap. Heck, during the CBR I did one in a motel room in 2 hours including porting the jug to match the case.

talindsay · Post by **talindsay** » Sun Jul 08, 2012 6:43 pm

First, if you are describing what the mechanic said then you need a different mechanic. Everything the above poster write is correct. Realistically, assuming you actually poured the oil into the oil reservoir and not either the air filter hole or the gas tank, and it didn't raise the level in the sight glass, you need to figure out where that oil went because it is either on the ground or in the frame somewhere.

But realistically, I wouldn't be too about the bottom end. The main bearing and the clutch are both oiled from the gear oil, and the fly side bearing, which is oiled from the fuel, is a much more tolerant and lower pressure bearing. The big end bearing in the crank could be a big deal but if you didn't go too far too fast it's probably okay.

I'd replace the whole top end, which costs $200 or so. But do it yourself, you'll be glad you learned how Thur scooter works. It's an easy job. The first time I did one I took for hours being very slow and careful, but now I can do it in 45 minutes. That should be all you need, but keep an eye on the big end bearing in the crank. And find out where the oil went!

JohnKiniston · Post by **JohnKiniston** » Sun Jul 08, 2012 8:22 pm

There is a warm/cold weather plug on the back of the carburetor that adjusts how much air gets into the carb box, With it removed you will get some oil sprayed out onto the back of the engine but that's normal and not a problem.

You might want to try another shop if they are saying you need TWO pistons, Your bike only has one cylinder.

A good shop should be able to check your cylinder and piston to see if they are in the acceptable wear range, if they are then why replace them?

Keep your old piston, buy new rings and have them run a a ball hone through your existing cylinder if everything looks good.

Is your scooter leaking oil? Are the floor boards wet with it?

Robbie · Post by **Robbie** » Mon Jul 09, 2012 2:50 am

racerx1,

Need some clarification here.......like, where were you pouring this huge amount of oil into and, am I to understand correctly, none of it was leaking out?
Currently, I am led to think you were pouring it into the fuel tank......that would keep the bottom end very happy but when it ran it would have smoked like the fires in Colorado.
If you were pouring it into the fuel tank, and it ran, I am thinking there is so much oil on the cylinder the compression rings cant even make compression......like they're riding on a oil slick.

So, please clarify.....where'd you pour the oil?

Also, I agree, the prices you have been quoted as well as the part counts are, shall we say, suspicious.

Looking forward to your next post.

Rob

Lokky · Post by **Lokky** » Mon Jul 09, 2012 2:53 am

Robbie wrote:racerx1,Currently, I am led to think you were pouring it into the fuel tank......that would keep the bottom end very happy but when it ran it would have smoked like the fires in Colorado.

Adding excessive 2T oil to the fuel is actually going to lean out your mixture. I am surprised his piston hasn't seized completely if this is actually what he did.

Robbie · Post by **Robbie** » Mon Jul 09, 2012 3:03 am

Lokky wrote:
Robbie wrote:racerx1,Currently, I am led to think you were pouring it into the fuel tank......that would keep the bottom end very happy but when it ran it would have smoked like the fires in Colorado.
Adding excessive 2T oil to the fuel is actually going to lean out your mixture. I am surprised his piston hasn't seized completely if this is actually what he did.

Agreed, but at that mixture level I don't think it would fire enouph to make much heat......couldn't have had any power.....or at least not enouph to hurt itself too much.

I gave the leanout a bit of thought but at that oil level......like sixteen to one or less......showing my age, that was the standard mix ratio for Lawn-Boy back in the early sixties.
When they went to 32 to one we were sure they'd be blowing up left and right.

Now, at fifty to one, they still hang in there.

Rob

Robbie · Post by **Robbie** » Mon Jul 09, 2012 3:06 am

Lokky,

Hope I spelled that right.......we met at Amerivespa.....I had the other blue 09.....you told me the story of your engine switch/bike build while we were at the hosting dealer on Thursday.

Was good to meet you.

Rob

PS....Hope my memory was correct

BuddyRaton · Post by **BuddyRaton** » Mon Jul 09, 2012 7:56 am

JohnKiniston wrote:There is a warm/cold weather plug on the back of the carburetor that adjusts how much air gets into the carb box, With it removed you will get some oil sprayed out onto the back of the engine but that's normal and not a problem.

That was the only thing I could think of....but I don't see any way pulling that plug is going to blow up a stock motor. Most people don't even know what it's for and either leave it in or out all the time.

neotrotsky · Post by **neotrotsky** » Mon Jul 09, 2012 8:07 am

A top end swap is, as others have said, pretty quick. I did my P200e in about 2 hours. Parts? Around $300 total.

I ended up taking my Rattler 110 to a mechanic (after losing the space to work on it), and it took about the same time. My Rattler also had a lovely quarter sized hole right in the top of the piston. It was epic! Never seen one so fragged... Parts+labor? About $500.

Your engine should be fine, and this sounds par for the course for a used 2-stroke. The nice part is that, with a Stella, as long as you follow the instructions on the tin and just do the basic matainance, that top end should last you 15-20k miles (YMMV). Yes, you'll need to do some tinkering. Yes, there will be cables that break, leaks that develop and things that need "tweaked". You did not buy a Honda. You did not by a "retro-styled" scooter.

You bought a REAL scooter. This isn't retro: It's IS built like the old ones, except that it was put together recently. This isn't advanced technology. It's very old tech.

I can understand the frustration. I had to give up my P200e because, for all the engine rebuilding and new parts, would not pass emissions by qualification of Maricopa County in Arizona. The ONLY county that requires emissions on EVERYTHING! If it weren't for that, I'd be riding that bike right now. But I couldn't get a legit set of tags and plates for it, and after so many attempts the DMV just kicked the bike out of the system. It seems wrong but I didn't have the time or the money to fight it. So, trust me... I get the irritation.

But, this is a simple fix and should not put you off of what is a great bike. If having to work on bikes and do regular maintenance like changing a cable and going around every week to tighten all fittings and bolts to keep up on the impending leaks and squeaks, then perhaps a vintage bike isn't the best. When you replace the top end and repair the carb, this won't mean you are done working on the bike. It just means that you got the worst bit out of the way.

racerx1 · Post by **racerx1** » Tue Jul 10, 2012 2:13 am

Wow, this board is really alive - several responses in one day. Thanks to you all for your time. The scooter is in storage at the shop so I can send any pictures but let's review:
BuddyRaton:
"There is not an oil float, it is a simple sight glass" -I guess I was mistaken. It sure looked like a white float in the sight glass. So, I guess the oil was always full in the site glass (no bubbles), but I added 2 quarts over 2 weeks trying to clear the sight glass of this mistaken "white float". I added it to the correct oil reservoir (even I'm not stupid enough to add it directly to the gas) & there was still oil in the reservoir fill tube 50 miles before I took it in for a tune up (last time I checked). The oil never leaked on the garage floor or on the body. It really looks like the engine was being coated with a spray out of the "warm/cold weather plug on the back of the carburetor". I don't know when this plug fell out. Carb compression seems to have fallen over the week before taking it into the shop - maybe 50 miles of operation.
JohnKiniston:
thanks for the tip on the warm/cold weather plug, which I'm still missing. No oil is on the floor boards. It only seems to have sprayed out of the plug hole. I still don't know to "replace the top end" or as you say "Keep your old piston, buy new rings and have them run a a ball hone through your existing cylinder if everything looks good."
TaLindsay:
"I'd replace the whole top end, which costs $200" - Would replacing the "top end" include this missing plug? You can see I'm way out of my depth here, not even knowing what the "top end" is.

I understood everything in the owner's manual but the service station manual & lack of tools is way out of my comfort zone. I'd love to hear more thoughts.

JohnKiniston · Post by **JohnKiniston** » Tue Jul 10, 2012 3:04 am

#15 in that picture is the plug I'm referring to. Don't worry about not having it, You don't need it.

The oil tank only holds about 1.25 quarts of oil in it IIRC, I have a hard time believing 2 full quarts went into it unless you did a lot of riding during the time between each quart.

Robbie · Post by **Robbie** » Tue Jul 10, 2012 11:52 am

Item 15 in the illustration is the air box plug that needs to be removed to access the carburetor mixture screw.
With it removed, the carb can pull air through that opening as well as the normal intake ductwork beginning under the seat at the 'bug filter' (my term).
If you are seeing oil coming out of this area it sounds like the injection pump is throwing oil into the airbox......sounds like the line has come free from the carburetor.

If this is the case, the engine has been operating with virtually no oil.
If I am on the right track, the piston, rings, and cylinder will likely be unserviceable from scoreing.

If a little oil was making it through the injector the crank and rod bearings might have survived.......thats a bit of a hopeful reach from me directed to the OP......You may be exceptionally lucky.

Regarding the top end question......this is when the cylinder, piston, and rings, and sometimes the small end bearing are replaced or refurbished.
The proceedure can be done 'in frame' and is a fairly straightforward 'nuts, bolts, screws' proceedure that can be accomplished in just a couple of hours if you take your time.

BTW.....I do think you should replace the plug in the airbox.....pulling air in from that area will dirty the air filter rather quickly.....that is a real dirty area back there.....much road dust and tire dust.

Rob

JohnKiniston · Post by **JohnKiniston** » Wed Jul 11, 2012 2:34 am

Robbie wrote:Item 15 in the illustration is the air box plug that needs to be removed to access the carburetor mixture screw.
With it removed, the carb can pull air through that opening as well as the normal intake ductwork beginning under the seat at the 'bug filter' (my term).
If you are seeing oil coming out of this area it sounds like the injection pump is throwing oil into the airbox......sounds like the line has come free from the carburetor.

It sounds more like normal blow back to me, As the engine revs you'll get a spray back through the reeds that'll end up in the carb box and with the angle the carb box is at it drains out that hole.

Robbie · Post by **Robbie** » Wed Jul 11, 2012 2:46 am

Well.....the OP indicates two quarts in 50 miles.....So, I doubt if blow back is the issue.

Trouble is we all give ideas based on a report.....I'd feel better if I could see a photo showing me how coated the rear of the engine is.
Some folks look at normal misting as a huge leak.....so we are all at a bit of a disadvantage on this one.

To the OP.....you really should give consideration to taking your machine to a shop the knows vintage Vespa's and Stella's.

These, on the surface, don't seem much different than a ole lawn mower engine but in reality, they are not complex but rather intolerant of incorrect service proceedures.

Just my opinion,

Rob

Lokky · Post by **Lokky** » Wed Jul 11, 2012 4:38 pm

I really do want to know where all his oil went if he added two quarts to the oil reservoir considering it holds about a liter and change...

racerx1 · Post by **racerx1** » Thu Jul 12, 2012 2:09 am

ok, I'm going to the shop & take a picture of the trouble area for ya. The missing plug/hole was not #15 at the air box. Definitely lower on the bike.
Thanks for the interest. I'll post tomorrow.

neotrotsky · Post by **neotrotsky** » Thu Jul 12, 2012 6:24 am

I'm still not *quite* clear based on that report on what's going on. A "plug" in the carburetor will not magically allow all the oil to disappear with out a trace. Perhaps I'm just being a bit thick (which is probably true since I just did two shows today).

As for Top End/Bottom End of engine:

When talking about bikes (and engines in general), most engines are divided up into "groups" of parts. The "Top End" refers to anything above the crankshaft. This includes the cylinder head, Piston, Piston Rings, Connecting Rod, Rod Bearings, Spark Plug and Valves (if you have a 4-stroke engine).

The "Bottom End" includes things like the Crankshaft, Engine Case where the cylinder sits, transmission housing and the rest of the engine body.

The Top End is actually pretty easy to replace on a Vespa. On a traditional car, the cylinders are part of the engine block (or "Bottom End") and need to be machined if there is damage or wear to the engine affecting performance. On a motorcycle, especially a two stroke bike, you can simply replace the entire cylinder! Then, all you need are new pistons, piston rings, perhaps a new connecting rod but definitely new rod bearings, perhaps a new head and obviously a new spark plug. This is what's known as "Pullilng the top end" and it's even possible to do this while the engine is still attached in the bike

(just remove the top mount on the rear shock, jack up the bike and set it so the engine swingarm is free standing and let the whole thing drop). This is what's most likely to need replaced when your performance dives off hard, you are burning massive amounts of oil or you have a seize.

BuddyRaton · Post by **BuddyRaton** » Thu Jul 12, 2012 10:17 am

Robbie wrote:Item 15 in the illustration is the air box plug that needs to be removed to access the carburetor mixture screw.

Yep....#2 is the winter plug.

To get the top end off you can also just pull the studs.

IF you added to oil to the tank you wouldn't be the first person...or the last to do it. Actually it would probably be the best explanation for everything.

How many kicks did you give it when you checked the compresion?

I'm starting to think that it all might be a fouled plug. Super heavy gas with oil...yeah it will be lean but it's not going to run long enough to kill the top end and it would foul the plug real quick.

racerx1 · Post by **racerx1** » Thu Jul 12, 2012 9:20 pm

Thank you all for the discussion. As shown in the photo taken today, the culprit is the air box plug that needs to be removed to access the carburetor mixture screw. I did notice some oil in the threads of the opening. We only assumed this was the source for all the oil coating since its in the center of the mess. If indeed the oil injection line has come free from the carburetor, the damage is probably well beyond replacing the piston & ring set. Am I in the market for a cylinder & bearing replacement, too? I'd consider selling it for parts, but I'm stick with a sidecar, too. Thoughts?

racerx1 · Post by **racerx1** » Thu Jul 12, 2012 9:26 pm

Another attempt to add photo.

Anyone work on Stellas in Western North Carolina?

racerx1 · Post by **racerx1** » Thu Jul 12, 2012 9:31 pm

PS: the oil was never added directly to fuel, so I doubt the lack of kick start is a fouled plug. It won't raise past 70 psi with 10 kick starts. Kick response got worse over the three days before going to the shop. We can't even start it there.

Robbie · Post by **Robbie** » Thu Jul 12, 2012 9:46 pm

Arrow points to location for part #15....plug that covers the mixture screw.
The cold weather? plug, mentioned elseware is currently visible in your photo...small rubber plug in upper air filter cover.

But, this view is of a engine that is not juicy enouph to have lost the quantity of oil described.......a pint of oil on the floor looks like a gallon.

I am without any further thoughts at this time.

Rob

racerx1 · Post by **racerx1** » Thu Jul 12, 2012 10:17 pm

so with no exterior drips (just the greasy black grit shown) perhaps that hole is just some blow off & I might just have a fouled plug?

Robbie · Post by **Robbie** » Fri Jul 13, 2012 1:36 am

racerx1 wrote:so with no exterior drips (just the greasy black grit shown) perhaps that hole is just some blow off & I might just have a fouled plug?

Well, if the engine is severly flooded the rings cant seal to cylinder walls.
That of course would make for low compression.
Just about any IC engine ever produced needs about 100 psi to fire the mixture.
So, fouled plug/flooded engine are possibilities.

But still.....this two quart of oil thing just doesn't play out......like where'd it go?
If the injector pump was throwing it into the engine at that rate the plug would've oil fouled.....the smoke would be clearing about now.

Your mechanic can drop the exaust and look into the exaust port. By moving the kick starter he will be able to see the side of the piston.....the exaust side generally scores first if a lubrication failure has occurred.
So, if scoring is visable, then pull the head and cylinder.
If no scoring is evident......well back to severe flooding.

But again, where in the heck did that oil go?

Oh well.....keep us in the loop.

Rob

neotrotsky · Post by **neotrotsky** » Fri Jul 13, 2012 4:06 am

If need be, just rebuild the top end, rebuild the carb and ride it! Seriously: With the side car that scoot is WELL worth the effort! It's not much. Granted from the pic it looks like your rubber and wire parts could be replaced because they are hella dried out, but if you got the bike in your possession and have the space to keep it/work on it, then why give it up?

The *only* reason I had to give up my Vespa P200e is because we had zero place to keep it or work on it if it weren't legally tagged. Otherwise, I'd still have it.

BuddyRaton · Post by **BuddyRaton** » Fri Jul 13, 2012 6:06 am

Good call on the rotted rubber so lets go back to basics

Do you have spark?

racerx1 · Post by **racerx1** » Sun Jul 15, 2012 1:33 pm

I thought it odd that the rubber/wire parts had dried out so soon. Now I suspect the odometer was tampered with. Does the Stella rubber really dry out in just 1,500 miles? I've never seen a drip of liquid oil, just the grit shown in the photo. I haven't been able to start it at the shop, so I don't know if I'm getting a spark.

BuddyRaton · Post by **BuddyRaton** » Sun Jul 15, 2012 1:59 pm

racerx1 wrote:I haven't been able to start it at the shop, so I don't know if I'm getting a spark.

That's why you want to check for spark, to see if you have one or not. If you don't have spark it's not going to start no matter what you do to the carb.

Either remove the plug or find another one, a new one might be best for you.

Pull the ignition wire off the plug in the head and place your new plug in the boot. Make sure it snaps into place and has good contact with the ignition wire.

With the plug set into the ingition wire boot place the plug electrode against a screw or something to send the electricity to ground. Watch the electrode as you kick it over. If you see a spark...good...if you don't see a spark...kinda good since you know where to begin.

neotrotsky · Post by **neotrotsky** » Sun Jul 15, 2012 7:21 pm

racerx1 wrote:I thought it odd that the rubber/wire parts had dried out so soon. Now I suspect the odometer was tampered with. Does the Stella rubber really dry out in just 1,500 miles? I've never seen a drip of liquid oil, just the grit shown in the photo. I haven't been able to start it at the shop, so I don't know if I'm getting a spark.

For all the things that are awesome about the Stella, there are a few issues. The lower grade Indian rubber is one of them. Yes, it does dry out quickly and does take some extra attention to keep it good. I use a little bit of armor-all/petro-conditioner on rubber parts for the Stella every month or so. It's just the nature of the stuff. Also, if you get Japanese or Italian rubber components they seem to last alot longer, but they are a bit hard to find.

JohnKiniston · Post by **JohnKiniston** » Mon Jul 16, 2012 5:22 am

racerx1 wrote:I thought it odd that the rubber/wire parts had dried out so soon. Now I suspect the odometer was tampered with. Does the Stella rubber really dry out in just 1,500 miles? I've never seen a drip of liquid oil, just the grit shown in the photo. I haven't been able to start it at the shop, so I don't know if I'm getting a spark.

The rubber dries out quickly on these bikes, Especially if they are left sitting.

The Odometer may not have been tampered with but there's no guarantee that it works correctly and that every mile it shows is a measured mile.

On my Fireball I've gone through a number of speedometer parts in an attempt to make my speedometer work and measure correctly, I've given up on it. Maybe someday I'll use a Trailtech on it. For now I just drive with traffic.

BuddyRaton · Post by **BuddyRaton** » Mon Jul 16, 2012 5:39 am

JohnKiniston wrote:
racerx1 wrote:I thought it odd that the rubber/wire parts had dried out so soon. Now I suspect the odometer was tampered with. Does the Stella rubber really dry out in just 1,500 miles? I've never seen a drip of liquid oil, just the grit shown in the photo. I haven't been able to start it at the shop, so I don't know if I'm getting a spark.
The rubber dries out quickly on these bikes, Especially if they are left sitting.

The Odometer may not have been tampered with but there's no guarantee that it works correctly and that every mile it shows is a measured mile.

On my Fireball I've gone through a number of speedometer parts in an attempt to make my speedometer work and measure correctly, I've given up on it. Maybe someday I'll use a Trailtech on it. For now I just drive with traffic.

One way to determine if a vintage or classic Vespa is real is the speedo. If the speedo doesn't works...it's a Vespa or Stella!

neotrotsky · Post by **neotrotsky** » Mon Jul 16, 2012 6:12 am

Bah! Spedometers are for the dim, the inexperienced or for those who actually enjoy following every segment of every law out there (they were usually the ones who were the class tattle-tale/teacher's pet as well I've noticed).

They do have a digital spedo replacement from SIP. It will cost, but looks pretty flash

double-o-soul · Post by **double-o-soul** » Fri Aug 03, 2012 8:04 pm

observations and suggestions from a noobie, because (and I mean no offense here) you describe things in a way that does not reflect even an intermediate understanding of the stella:
1. the plug in the back that covers the mix screw is irrelevant. so many people run without it.
a. the 2stroke oil in the threads at the mix screw are because the airbox is slanted and any 2 stroke there is anywhere inside the airbox is going to drip out the mix screw hole
b. the gobs of 2 stroke oil probably ended up somewhere on the road through this hole without you knowing.
c. SUGGESTION: if you can get the bike to idle at all, with the airbox lid off, spray some carb cleaner around the oil injection pieces (the almost pentagonal looking piece at the bottom of the airbox underneath the choke cable) if the idle sound changes, try tightening the screws because that would explain so much (the disappearing oil, the oil in the mix screw hole, and the other symptoms)
2. (again, this is if you can get it to idle at all) while the engine is idling, jiggle all the wires you see to find out if the problem is electrical. I have some experience with a bad spark plug connection to the ignition coil vexing local scooter heads. it can make you think the jetting is off, the timing is off, etc., etc., when all it is is a bad wire or bad connector.

daveyd007 · Post by **daveyd007** » Sat Aug 04, 2012 10:25 pm

"Combustion pressure had dropped to 70 psi"

It's no use to check for spark because the engine would not run having 70 psi of compression.

I once had a two-stroke engine that read 90 PSI on compression gauge. It would not start and it turned out that it had a pinched piston ring. A pinched ring can also be caused by the crankshaft bearings starting to fail. Bits of the crankshaft bearings can come up through the ports and be caught by the piston in the port pinching the ring in it's groove. The only fix for this is a total engine rebuild. That to me, is your best option unfortunately.

racerx1 · Post by **racerx1** » Sun Aug 05, 2012 7:20 pm

Thanks for the articulate & informed response. I will pass your thoughts onto the shop. And I am in no way offended being called a noob. I am a total noob & rely on the kind suggestions & admirable experience shared here. Cheers!

BuddyRaton · Post by **BuddyRaton** » Sun Aug 05, 2012 8:25 pm

Double o makes some good points. Nobody runs a mixture screw plug...they go the way of socks in the dryer.

Here is what I would try. Retorque the head bolts Pull the plug, turn off the fuel tap off and kick the snot out of it. Recheck the compression. Check spark, reinstall plug and see what happens.

If compression is ow and spark is good pull the head and jug and see what is going on.

double-o-soul · Post by **double-o-soul** » Mon Aug 06, 2012 4:42 am

who told you the compression was low? are you absolutely sure of this?

BuddyRaton · Post by **BuddyRaton** » Mon Aug 06, 2012 7:25 am

double-o-soul wrote:who told you the compression was low? are you absolutely sure of this?

Yeah the "low" compression is getting me too. According to the OP it was starting and running OK and then had low compression "due to damaged pistons & rings"

If you snag a ring, seize a piston etc those are major events that will be noticed and ofter require a change of underwear!

Find a Vespa/Stella mechanic. If none available drop the motor and ship it off to a reputable rebuilder. Yeah they are simple motors...but they have their quirks and certain things that are different from other 2T motors just need to be done correctly. It sounds like your mechanic may be in over his head.

Modern Buddy

Stella carb question: What's your opinion?

Stella carb question: What's your opinion?

answers to all the kind responses

Thanks, double-o-soul