Modern Vespa

Hi all,

Been working on an 05 stella that has been sitting for about a year, last time I rode it the engine ran away and I got zapped pretty bad yanking the plug wire off to kill it!

After a long break we are trying to put back together the pieces.

By doing a pressure test I learned there was a large air leak coming from the clutch side seal. So I cracked the cases and found the culprit, pictured. There also seems to be some damage to various adjacent engine parts, probably from when that chunk of seal buzzed through the case (but could be older, it has a pinasco cylinder and the cases have definitely been opened before - so much grey permatex!). Pictured is all the damage that seemed potentially serious, on the piston, cylinder, and a crack in the flywheel side case. The crack had permatex in it which makes me think it could be an old injury?

Anyways I'm wondering how you all would assess the damage/ what you'd recommend reusing vs replacing. I'm not trying to break the bank on anything, just get it back on the road... was hoping to just purchase a rebuild kit from scootermercato and leave it at that... alas.

The scoot also has a 177 pinasco cylinder on it from a previous owner, not sure if I'll need any special gaskets for that for the rebuild? There weren't any when I took it apart just some nice gobs of grey permatex . Other than that I believe the engine is stock.

Thanks for your thoughts

The biggest problem is getting a clutch side seal to now stay in. When they have been run that long with a failed seal, the case wears. New seal will be a little loose. Might hold with loctite, might not.
Case crack is nowhere important. Cylinder scores look terminal.
A good opportunity to put back to total stock for the cost of a rebuild kit and used stock cylinder.

Hmm ok thanks for the advice. Where might one source a used cylinder/piston? I just checked the for sale forum here and scooternet2, there's a "freshly honed" vespa super 150 cyl and piston listed. Would that be compatible? Looks like probably no. Ebay is full of cheap new stuff, I'm not very confident about its quality.

The Stella is a "5-port" engine so that 2-port Super cylinder probably won't work too well for you.

I have a bunch of Stella parts at the shop. I can go see if I have something usable tomorrow.

Amazing thank you!

Further to Jack's comment, your biggest issue is possible damage to the clutch-side case half where the crank seal sits. A photo of that area would be instructive.

Your second biggest issue is whether you still have the o.e. LML crankshaft. If yes, it is only a matter of time until it fails. In fact, I wouldn't be at all surprised to learn that is what took out your seal.

Can't get a good photo right now, but from my (beginners) inspection the clutch side seal seat seems pretty much unblemished. Or at least it doesnt have any dings in it, could be worn evenly all the way around I suppose.

I havn't gotten the bearing out yet, planning on replacing but it spins smoothly in there now. As does the crank which is out. Would a failure in either of these parts be noticable by eye or could it be pretty miniscule? Does the seal failure indicate other failures?

BS advertising. a Stella motor has 3 ports. Just look at the cases, there are 3. . not 5 or 9 or 6.

but yes, the 2 port cylinder will not fit 3 port cases.

Yep. Hence the air quotes.

The classic etiology for an LML crankshaft fail is the lads at the factory pressed the cranks together with inadequate clearance between the webs and the big end bearing. That results in insufficient oil reaching the bearing, causing the bearing to overheat. The weak link inside the bearing is the bearing cage, which is just thin, stamped steel. Eventually, the excess heat causes the bearing cage to disintegrate, and fragments get sucked into the motor. From there, it is a crapshoot exactly what kind of havoc they will cause.

If I was you, I wouldn't spend too much time thinking about this. I would just determine if I still had an LML crank and, if yes, I would just replace it.

Also, I noticed the damaged clutch side seal was one of the rubber types. Stellas came with the metal type. Others may disagree, but my advice would be to go back to the metal type.

Hi Fynn.... Carlos here. It is nice to see you wrenching on your scooter and learning. Unfortunately I no longer live as close to you as before but in the past I did helped you several times and I got your scooter running much better than before.

It is now too late to check for compression, I do have a compression tester. Never in my life I would imagine that your engine had that many issues. It always felt extremely weak from the day that I first tested it. I never ever in my life would endorse another Pinasco cylinder after my own awful Pinasco experience. Should I be surprised that your Pinasco cylinder failed? absolutely no, to me they are total and utter crap!!! Obviously you got this scooter with the pinasco cylinder kit already but it was barely running.

I have been on Malossi cast irons for over 11 years on my PX150 and I had polinis Cast iron and other current Malossis aluminum and they are very strong.
If you decided that you have to get another cylinder kit I would recommend anything but pinasco.

Anyways, I saw your pictures, that piston looks terrible in my opinion. The box of random parts that you gave me included the original cylinder and a cylinder head but not the piston and a crankshaft that has some resistance. I still have it if you want to re-use it but you will need at least the piston.

I don't know what you want to do with the block(engine cases). I personally would recommend sending it for repairs to a specialized shop or just scooping a used one. I am very aware of your situation, you don't want to dump a ton of cash into this project because perhaps is not a good idea. As you and I know, your scooter was kind of neglected and you were trying to get it back on the road in good faith and in a budget.

You have a few shops that can do the job(scooter west, scooter mercado, Gikspeed, scooterspeed in Cali) and maybe others but you might as well just slap on an already running engine.

The thing with your engine is that it was already bad before and someone put a Pinasco and runs as bad plus is damaged. Ask AZlynch (Sean), he can probably out source you the engine cases. I wish I can help you more but I am at least 40 minutes away from you now and much busier, before I was like 10-12 minutes away from you and had more time.

Anyways, I hope you are doing well. I might stop by sometime just to take a peak. I am happy to see that you are wrenching. Take care!