Modern Vespa

I dug into the GL's motor to get at the fly side case half so I could weld up the hole where the JBWeld broke loose tonight and was not really prepared for the carnage that awaited me.

First, the fly side seal was literally in two pieces. Then, the inner race for the fly side bearing was protruding out of the case.

And once I got the cases split, the kickstart gear was chewed up and there was more heat damage on the fly side of the crank's big-end bearing.

And the fly side bearing itself wasn't looking so hot, either.

Now for the good news. Welding up the hole in the transfers went swimmingly. There are two small pores visible from the inside, but they don't seem to go through to the outside. The pressure test will obviously be the real measure of success, but I'm still a fair way from that yet.

So while it was a lot worse than I was expecting, it's nothing I couldn't or can't handle.

Never a dull moment in my workshop.

How????

26HP

Also, something must have been just a little bit off true.

Jeeeez!

But that weld repair... Looks good enough to eat

Thanks!

Having even a little bit of experience makes a huge difference. I also practiced and got my settings right before I did it.

I think I know what happened with the bearing. When I was welding the clutch side cases, I noticed when I pulled the cylinder off that there was a tiny bit of weld spatter, like smaller than a pinhead, which I hadn't gotten filed quite flat. I'm guessing that put the cylinder justa hair off true, causing the carnage.

Regardless, better to find out this way than having the whole thing explode on the road.

Agreed, could have been a whole lot worse with you sliding down the road sideways. Good man.

Still crazy damage…

Not that it's huge damage, but moving bearing race? That's pretty extraordinary.

Usually you can't get that off even if you wanted to!

Repairs look swell though! Top stuff

I'm sure you realize that a standard factory case is unlikely to be strong enough or manufactured to adequate tolerances to withstand the forces of that much power for very long. I'm sure it's a blast, but it's a short one. From that perspective, the resulting carnage is not a let down but rather part of the fun. It took me awhile to understand this about a certain segment of performance builds.

In those flesh colored riding pants that look like shorts

Oh, I live this fact with this build every time I take it out. Nothing in these motors is designed for these sorts of stresses. This is the second set of cases I've had it in. The last ones cracked too bad to fix on a missed shift that also took out 4th gear and the xmas tree.

I'm now at the point where I have the confidence to start welding in reinforcements where feasible, but haven't done that to anything just yet.

Once I get parts in (I don't have a spare fly-side bearing), it'll go back together after I make sure that the high spot on the deck is fixed.

I call them my "Wheelie Pants"

I figured it was a proof of concept kind of thing. I have eyed the Malossi cases from time to time and wondered about their capacity to hold up under the stress of a high performance build. I would love to have one just to have one but I can't justify the expense for the modest performance increases I am considering. The BFA cases look even beefier for your kind of build.

It's not a Proof-of-Concept. It's a whip-ass-fast Daily Rider until it's not.

Hence the need for multiple scoots so I always have something to fall back to.

At some point I'll probably start buying purpose-built cases, but not yet.

Good lord.

Every time I think I have seen it all you have a new adventure that proves me wrong.
I appreciate the education from the cheap seats.

That engine is going to have to think of some new ways to beat you. That was some attacking salvo. All repaired to try again.
Will you run that mazzucchelli till the big end goes or fit a new crank now?

I'll run the crank until the big end fails. There's no signs of grinding and almost no lateral play. I'll get it back together next week after I get some parts ordered and see how long it all lasts this time.

I still need to figure out if the cruciform or gears are ready for replacement or not, too. It's a hardened Crimaz and peeking at it with the gears still on the driveshaft, it looks like it's still in pretty good shape, but who knows.

Like it or not, I live my life as a cautionary tale to others.

Did all that carnage end up seizing it?

Nope. Top end is still just fine. These little motors are tougher than people give them credit for.

I know I've told my broken cruciform seizing gearbox story. I think my biggest fear has been seizing, but I have kind of gotten over it. Bottom end seizing is probably pretty rare. Top end seizing causing hard lock ups is probably pretty uncommon too. Yes, these engines are quite tough and I am too dainty working on them. I was going to ask at one point if anyone ever spin balanced them and thought better if it.

I'm so far down the "stranded by breaking things that should never break" road it's not even funny.

Shattered cruciforms. Broken gear teeth. Shattered cases. Mangled clutch plates. Spun clutch. I even snapped a driveshaft somehow. Still haven't quite figured out how that happened.

Hard seizes are relatively uncommon, but they'll definitely get your attention when it happens. I hard-seized my Sprint doing about 60 when a cylinder stud worked its way loose. I was still able to fire it back up and ride it home. That was a cast iron Polini 177. You do that with an Aluminum top-end and that jug is never running again.

After working on them long enough, I guess you become like one of those special forces guys who can find all the pieces of his rifle in the mud and reassemble it in the dark. The videos of the SIP guys building engines in their Euro kitchen make me chuckle…Und das ist der tool fuhr torquing die license plate to eksakly .2 Newton Meters. The dirt floor of a mud hut will work too. But I am more like the SIP guys than I would like to admit.

Fun fact: long ago and far away, I was able to take all the pieces of an M16 and M60 in a single pile and re-assemble them in complete darkness, and do it FAST.

These days, I prefer to do fast assembly of things like poorly-shot and -edited youtube videos of my workshop adventures, so here's the video from last nights welding session.

Yeah…I'd end up shooting myself doing that even without a firing pin in the pile.

Looks like you've found the angle of dangle on the spool gun. There's nuthin wrong with that welding; no voids or inclusions…not a booger to be found. Many hectares of port space are now within your grasp.

And this was much harder than just adding meat to unmolested cases. I had to deal with paper thin walls that pulled back, then build from there. I'd practiced on a hole in an old case half, so I knew what was going to happen, which makes a big difference, too. Welding really is amazing. I'm really glad I finally got going with it.

Not listening to people who tell you it can't be done helps too. It's not like a my little pony I can do anything wowee rainbow attitude. It more like… The fuck I can't, kind of mindset.

you need a mill.
🙂 "Skorts"

I'll grant you - that is a mighty unique implosion.
My $.02:
If you find you have a leak in a lower pressure area of the cases - due to a pinhole - consider using a quality epoxy and smearing it over the weld area on both sides - to seal everything up.
Welding with a gun rather than a torch is like doing surgery with a fork - well - perhaps a knife - but I am talking kitchen not scalpel.
Without a torch - you cant concentrate on an area and get it fully molten - a trick that can be used to get rid of any pinholes -without adding material.
Gun is either feeding more material - or not.
So consider pin hole fixing with quality epoxy.
Hit both sides so you know you'll get good life.
Torque bolts and don't forget the cotter pin.
-CM1