Modern Vespa

1970 super 150. Spilt the case because the crank was getting stuck in one spot.

Does this rotary pad look home garage fixable or does it take a more professional touch?

Ooff…thats pretty rough. I'd lean toward sending out. That would need alot of epoxy to make it whole, which is no bueno. Hot Rod Scooters or Saints Engine can do it

Send it out. No more Saints Cycle repairs. They sent it all to Al.

https://m.facebook.com/HotRodScooters/

Epoxy will work.
However - the question is: for how long.
The epoxy is softer and will wear with time/use.

In truth - no one here can tell you exactly how long that will be.

I think the repair is about $500 -$600?
Others can confirm.
It may be worth it if you want one and done.

However - if 2500-3000 miles of perfectly good running was sufficient until you needed to repeat - my guess is that epoxy would do a nice job for you.
The biggest risk is your time.

Either way - you should replace the crank and have the new crank there for the repair job.

My $.02

It's probably going to be less expensive to buy a set of nice used PX150 or Stella cases, than it is to correctly repair your cases.

That's a bigger missing chunk than I would want to repair with JB, but it would probably work. I think JB weld would hold up indefinitely for a skim coat, but hard to say for a deeper repair. It could still last a long time.

Repairing the case with welding would be a much better solution, but sourcing another used case might be a cheaper option.

I have a welded rotary pad repair on a VBC case that looks like it was done a very long time ago. It's good work. There was a time when such a repair would not have been so exotic and a local machinist could have figured it out. Those days are long gone.

That's pretty deep.

I too have used a 2-part epoxy as a filler; applied by 2 point utility knife blade as a squeegee. This is on scratches and small imperfections.

however, what you have there exceeds the limits of what i would feel comfortable with on an engine.

you have several options-
-send them out to be repaired and god only knows how long that will take.
-Find a set of used cases out there for less than the repair and time above.
-go nuclear and buy a set of Malossi cases. This will be a different platform and cost you extra as some changes will have to be made with parts.

just depends on your expectations, pocket book, and patience.

4th option- reed conversion. Worth considering if doing other tuning parts as well. Cost more than nothing, but probably less than all new parts.

If I was doing a stock build, I'd search for a set of replacement cases.

4th option+
https://www.sip-scootershop.com/en/product/intake-manifold-drt_40311600

This is a bolt on repair. Grind out the damaged rotary pad entirely and it will be slightly more powerful too.

Now that is very interesting indeed!

oooh...that could be interesting for many projects. Especially if you want to keep your autolube.

With autolube this drt one it isn't bolt on. But as premix, if you have a fkd pad and no plans for more than an SI, this is a great solution. There is at least one other type of this style reed block but can't remember who makes it.

Thought it was MRP but was wrong. This one has been around for a while, I know a guy who has installed a few of these with good results. This one is a lot cheaper than the DRT but certainly less fancy... whether one is better than the other I don't know.

Looks like they are made for LTH - https://www.lambretta-teile.de/Reed-valve-manifold-for-below-Si-carb-Vespa-PX-Sprint-VNA-VBC


Showing stock at LTH, no stock at SCK (but better pictures!)
https://www.scooter-center.com/en/intake-manifold-for-reed-valve-lth-vespa-vna-vnb-vbb-vbc-gt-gtr-sprint-rally-px-cosa-reed-valve-below-si-carburettor-3331597

Apparently doesn't fit the "short" sealing surface cases - see the last pic on SCK.

That is 100% fixable. Listen to this because is gold: a few years ago I was tuning my P200E. For some reason it was running better without the air filter. Somehow the idle screw spring got sucked into the carburator intake and got pinched on the rotary pad and made its way between the cylinder wall and the piston. The engine still ran but I put some grooves into the rotary pad, the piston and slightly on the cylinder.

Go-Gogorilla scooter club in Tucson helped me out, big thanks to baldJohn back in the day. Someone was able to reapir the rotary intake casing using a incredibly strong bond used on mining. This thing was like a diamond. It was moldeable just for the first few minutes and we were able to contour the rotary pad case area. We let it dry hard for 24-48 hours and slightly sanded it down. We pressure tested and it was perfect. My compression has been very strong ever since specially with the Malossi 210cc.

In short and in summary, YES. Absolutely you can fix it. You could weld aluminum to it or you could to a sleeve or you can put strong bond.

This sounds interesting. Do you know what material was used? JB weld or Devcon is generally used, but I wouldn't trust them for this deep a repair job.

Anything is fixable with enough time money effort blood sweat tears miracles luck sacrifice and offerings to the god of speed. It's all how the equation adds up for the best possible outcome.

Thank you for this! Any scooter repair requires blood. Going fast requires these other offerings.

I recall that repair. The idle screw worked loose and the spring found its way into the intake. The gouges were a bit smaller that the ones in this Super case. Maybe JB, but this looks more like a CM2 or other pro-grade solution may be in order.

You can repair some pretty deep gouges in the pad with just JBWeld.

My VBB's pad didn't look much better than that when I first got it and then held up through fifteen years of abuse, including being ridden in everything from sub-zero to 100+ temps.

The key to success is definitely the prep. Clean the crap out of the pad, then heat it with a propane torch to sweat out any oil or contaminants in the pores of the aluminum, then clean the hell out of it again.

Mix up the epoxy, smear it on, then install the crank into the case with a piece of wax paper or plastic wrap. Let it sit for 24 hours, then remove the crank, clean up any stray epoxy, and continue your build.

I couldn't tell you exactly what bond was used, but I do remember the guy that helped me out saying it was an extremely strong bond used for mining. It was a paste, grayish in color and it was moldable initially and it was applied with the fingers and thumbs, somewhat filed but it wasn't still the second day when it was finally smoothed out when it was dried hard. My compression has been very hard ever since with the engine starting typically on the second kick.

I wish I knew the actual name of the bond that was used but that was like 10 years ago and I never seen this person again. It would have been something similar to JB weld that can withstand some temperature as well.

Or you can use Aluminum alloy low temp brazing rod. Harbor Freight and a cheap propane or Map torch. Would have to be prepped just like jbweld would and sanded to form afterwards. From their site: Weld aluminum with any low temperature torch - even a propane torch. These aluminum welding rods are harder than mild steel which results in minimized parent material distortion during welding. You'll also get a stronger weld than the parent aluminum material without flux or other welding material.
Harder than mild steel
Low working temperature (730° F)
No flux or fumes
Excellent corrosion resistance
Minimize parent material distortion during welding

I've been curious about those. It should work in theory. Maybe I will try it on an old case sometime.

The hard part is finding someone to machine it.

Necessity is the mother of invention. Have you seen backyard head decking on sheet of glass with sandpaper? I would entertain the idea of build a jig on 3/4" plywood. Mount the case on it. The "machining" required would be centric around the crank hole in the case. That can be precisely measured and a "hub bolt" mounted in the middle. From that bolt you can brace it in double shear with a support arm (2x4 or metal bracket) to keep its location fixed. Then you can create a retaining strap(actually 2x straps to keep parallel) to hold a Dremmel with sanding drum at the maximum desired radius. Lots of different variation to accomplish this. Fix the Dremmel or drill holding the sanding drum. Create a turntable with the plywood and perform similar material removal by rotation of the table. Go to an emerging market economy and you see all kinds of stuff like this. Lots of examples of creative manufacturing and repair exist.

If you are already at the point that your going to replace, no loss in giving it a try other than a small investment and time…and maybe frustration or reward 🙃

I admire the idea, but that's gotta be one hell of a plywood dremel jig to get the .05-.1 pad/crank gap!

Ooh 0.05-0.1mm would take more precision. Assume this would normally be machined in a shop with an end mill and rotary table, not going to get there without a cutting tool.

I have used these rods. It would be hard to fill the pad area because the base metal ( case) has to be hot enough to melt the rod to and you can't build it up like welding or even lead. For it to stick it all has to be melt-hot and it just liquefies and flows out. You can't touch up a small area because the whole thing has to be that hot. Make sense ?
You could make a form and fill the area and then grind it but the alloy is much harder than the aluminum and you;d be better off just getting it filled with aluminum by a good welder than messing with this alloy rod.

That's good to know. I would imagine it wouldn't work very well either for adding material to cases for enlarging ports. A TIG welder is on my list, but not so much for Vespa case work. Would also love to get some oxy-aceteline tanks. I haven't used my torches in years.

I thought Jack's kit for reed was pretty slick for robust /reasonable cost.

Forgoing that: As for epoxy vs rods…

The clearance of the pad to the crank is the same as the clearance of a cars main crank bearings to crank shaft journal.

It's tight.

U can't sand your way there.
U can hardly CUT your way there with a mill.
This the glued in pad option was born.

Im not sure how anyone could use those rods and rebuild a pad to spec due to the sanding/shaping needs.

However - if you are going low cost - keep in mind the following: most epoxies perform BETTER at a certain thickness.

Usually findable in the TDS or technical data sheet.
Those gouges are actually better for some epoxies than a paper thin layer.

Speaking of thin layers, you can grease up some shim stick at the preferred clearance and insert it between the crank and the pad when u repair.
This will create an exact clearance as specified.

I like to assemble the cases (with bearings) and torque, so the pad cures with the crank in place and everything square.

Highly likely this was a belzona product, they make all types of industrial epoxys from mild to wild. Quite a few metal repair solutions they offer that are fully machine-able and as hard as the base metal.

That stuff sounds amazing!
https://www.belzona.com/en/products/1000/1131.aspx

Ouch. That looks a lot like my rotary pad after the small end bearing disintegrated on my PX150 and the roller bearings got sucked into the crankcase and ravaged among other things, the rotary pad. All in a few seconds! WTF is that noise, wham, bam, seize!

The following is not a paid endorsement…
Al at HRS did an excellent repair job welding in a new aluminum plate to replace the pad.

And, he's just re-opened the business!

https://www.facebook.com/HotRodScooters

I have used Charlieman's method of rotary pad repair. I used 2 pieces of waxed paper between the crank cheek and the pad with the cases bolted together while the JB went off. I had measured the wax paper with a micrometer to make sure they were the correct clearance. Will see how it goes. If it fails, I will send the case to Al.

This is the factory maintenance manual method for fixing a damaged rotary pad, btw.

Yup. It's a bonafide factory repair. I really didn't like the idea of using JB weld on an engine case, but it works well with good prep. When I repaired the pad the second time, I tried burning out the old JB with a microtorch. Wouldn't touch it. The slow cure JB is good up to 500F.

Listen to charlieman. Done right, epoxy is a great fix for the pad. It isn't exposed to high heat. It's constantly being washed by the cool mixture. The most important thing is getting a good mechanical bond - i.e, a well scuffed and squeaky clean surface so it adheres.

Clean clean clean.

When you think you have it clean - uve started.

Scuff as SoCal notes.
Then you can clean with brake clean.
Then you can soak in acetone if you wanna.

Scuff gives you mechanical bond.
Chemicals clean for chemical bond.

Orwell has a little blasting cabinet I think. That's a nice prep if u have access.

Beauty, eh! I like it. 👏

I repaired mine with Wurth chemical metal or epoxy. Similar to JB Weld but I would assume worth to be a superior product.

Details are in my thread here but it runs anyway. Glad I didn't go to the effort of welding machining and all of that work.

First Vespa - Cosa 1