Modern Vespa

If the cases are still split, tap out the circled stud, clean the rust and grease it. You don't want this seizing in the aluminum, since it's the only stud that gets all the road crap through the swingarm's hole...

Excellent SaFIS - will do. Thanks for the heads-up! This is the VNB5 case. The VNB2 case bolt is out and clean...

Thank you for the recommendation to read this, I can see that there are plenty of helpful people that roam this halls. I look forward to tapping into that knowledge.

Great write up so far, thank you and keep up the great work. I know it can be difficult to both document and get things done.

We worked on the VNB2 today, no bitchen riding like Steve McQueen or Malcolm Smith, but it is two Sundays in a row we got to wrench. So here's the writeup

We put the case halves together on the VNB2. MJRally called at the perfect time and imparted some words of wisdom on how he puts case halves together, which we followed.

Then comes the piston and cylinder.

I almost made the call to blow off pressure testing it cause I was looking for the kit I put together, and where could it leak from anyway, right?

Well, After dinking around with sealing up the carb intake with a big slab of rubber, it was still leaking...from the top of the cylinder! So off comes the cylinder, new gasket coated liberally with red RTV, and voila - the leak was fixed.

So we checked all the other seals. An ever so slight bubbling coming out next to the metal seal of the flyside seal. Not enough to pull apart. It held air for 5 mins at 150 ppm, so it was technically good to me, but we put it on it's side and wiped a bit of red loctite on it. Hopefully that'll handle it, and if not, it's not enough to damage anything. It literally made one dinky bubble after the loctite was put on there, so after it dries, it'll be fine.

Chris says "So the lesson learned here is - If either one of us puts an engine together without pressure testing it, you get a swift kick in the nuts". Ha!

Installed the stator and flywheel.

Managed to install the old clutch, only to have to remove it because I forgot the washer that goes on first, between the seal and the clutch.

And we chased some threads of the oil plugs. We JBWelded magnets on the ends and I got a bit of JBWeld on the threads. Nothing that a die didn't fix in a couple minutes.

And that's as far as we got. The clutch cover and actuator arm need to be installed, all the rear wheel stuff, carb, and test fire. Then it'll be ready to go back in!

Oh, we did put a compression gauge on the spark plug hole and with a few easy kicks it was at 140 psi.


The flyside case is on the hotplate

Cylinder is on

Holding air nicely!

The leak was initially right at the top part of the cylinder. Reapplying RTV took care of it!

An ever so tiny leak was happening between the case and the seal, on the right, at 3 oclock. Put some loctite in the seam and calling it good.

Stater and flywheel installed

Clutch and carb installed.

Home made chocolate muffins?
Your posts are better than the British Bakeoff channel.

Safis or others - what is the best way to remove that stud that get's rusted in place on these cases? I was afraid to do anything else with mine for fear of cracking the case. Wouldn't move at all.

Ha! Naah, store bought, and I just like pastries and coffee

As far as getting that bolt out: I put the nut on the end and gently tapped it, then got a little more forceful, and it started moving. Then I put a punch on it and a few more taps, and I was able to get it out. I'd imagine heating the case and tapping for a really stubborn one, and using Kroil oil would do it....

Looking good. (Muffins too!)

Since most of times it's a full rebuild, including silent blocks, I soak the cases in a tub full of diesel fuel. Penetrates and lubes everything. But there will always be that ONE...

This one was drilled from both sides to get it out...

so it begs the question - so long as the threads are good and all, it it's stuck, why not just leave it be?

WOW - I'm glad this one came out fairly easy.

Adding it to my list of must do's any time an engine is opened up. Thanks for the info SaFIS!

John, dissimilar metals, galvanic corrosion. I have seen aluminum cracking from the expansion of the corrosion...

Ah so the concern is the eventual damage to the case, that makes sense.

Wow - that bolt Safis shows was my concern...
Have heard the vat of diesel for a week method as well.
For us home garage types - I suppose heat and some more modest form of soaking might be in order.

SDJohn - I in fact just let mine last time - but I don't know if it would hold the torque of another re-tighten if I had to split again.

qas - project looking good overall!
That fly side seal on the older cases is a PIA.
Think I am sold on using one of the DRT adapters that allows insertion from the outside on my next build.
Thanks for allowing me to chime in.
Carry on!
-CM