Modern Vespa

So folks might recall that last fall, I had the JBWeld filling in where I broke through the cases come loose and leave me stranded and pushing my GL home a mile or so.

Well, this week I had the replacement JBWeld on that same location come loose again, but fortunately my daughter was around came and picked me up, so I didn't have to push it home, but I was still pretty irritated about the whole affair.

So I decided that in pennance for recreating my failure, I'd fix it right.

First, I said Five Hail Gick's, then I headed over to the welding supply store and picked up a bottle of 100% argon and got to work. Tore down the motor, cleaned everything up, then built up aluminum weld until things seemed filled in.

Then, I ground the port back out, put it all back together, and pressure tested it. And it failed. I have pores in the weld that're leaking on me.

So I peened it down and tried building up more weld, but that didn't fix it. Should I grind back some of the new weld to get a better surface to work with and build it up again?

Anyways, I'm at least *trying * to add meat to my transfers correctly now. It would also be a lot easier to do this pre-emptively when the cases are torn down, but I'm starting out in Hard Mode anyway.

Shoulda used JB Weld... it woulda looked better... bet i coulda made it work

Well, you did mention the word "Gick"in the fourth paragraph. Would he not be a logical solution? There's no shame in paying a skilled technician to do it right, is there? Just sayin'.

I'm going to grind it down smooth enough that I can see what's going on and have another go. I actually have JBWeld on the transfer next to this one that's held just fine, but this one has now failed twice and I'm over it.

Assuming that the grinding and re-welding doesn't work, I'll probably JBWeld on top of the weld material, but hopefully that won't be necessary.

And Nomad, I do this stuff because I want to *become* an expert.

That's a BIG hole, by the way. Have fun.

It's filled, I just have pores in the fill. Worst part was having to grind a bunch of material back out of the ports.

Shame you didn't have some scrap to practice on/dial in first.
Did you preheat it with a Mapp torch?

I practiced enough to get the bead laying down well, but didn't pre-heat it the target area. I was more worried about getting the weld to build without pulling back and further enlarging the hole.

That is a big hole so I would expect a couple rounds of adding weld material and grinding down. I think even if you were welding steel it would go the same way. I have never welded aluminum, but your welds look cold. Have you tried heating the case? I've seen videos where they heat a case and check it with a laser thermometer, weld a little, more heat, more welding. Aluminum just sucks up tons of heat and conducts it everywhere, which might be why the parent material is so hard to melt and flow. Steel seems to hold heat closer to where you are applying it.

The case also looks pretty dirty where you are welding...a dirty hole as it were...

I had a bizarre and freak mishap with my P200E years ago. I was running for a couple of days without an air filter nor a carburator lid. Long history short the idle screw came lose and the spring got literally ingested by the intake rotary pad.

The crankshaft was stronger than the engine case so the spring grooved the softer rotary intake. The spring also made its way to the cylinder and groover my piston.

I had a local shop of vespa riders try a paste bond similar to JB well and it worked perfectly. I was told that this bond was used in the past and it was a paste/bond from ground drilling bit industry and it was super strong. My engine case has been perfect ever since however I didn't have a much damage as you had, mi situation was more of grooves on the rotary pad instead of a hole.

That makes sense. I consider a scored rotary pad a perfect application of a metal epoxy, but not one missing chunks, not so much.

I totally get wanting to learn for myself how to weld a case, at least as far as adding material for porting. I had the same idea about getting a spool gun for a MIG welder. I would expect it to take longer for a good result but if you don't build many engines, who cares? It's not that I'm cheap. It's more of a self sufficiency thing.

You're coming at it from the same place I am, Orwell. I don't build a ton of motors, but the ones I do, I need to add meat for the transfers.

While I don't think I took a picture, before I started, I'd cleaned up both sides of the case with a brass brush on my drill along with acetone followed by brake parts cleaner. It was bright n' shiny to start.

The weld temp was a tricky one. To get started, I was struggling to keep the deck from sagging due to heat. then, it flipped around to keeping it hot enough. I think that once I can grind it down some and get a good look at where it's porous, I'll be able to finish the job, I just ran out of energy for it yesterday.

Can you post an after-grinding pic before the tig snobs show up?

At least you now have some real aluminum to work with.

LOL! Sure! I'm just about to head out to the workshop and start grinding.

I think the other CM, peened aluminum down to compress it to alleviate part of porosity issue. Maybe peen it down to clean it up then fill in a bit more.

He did, and I went that route, too.

After a couple rounds of grinding and filling, things were better, but still not quite good. So I pulled the top end off and went at it from the inside, where I had a much better view of the problem--there were four pores so I dialed up the voltage a little, hit those, then ground them back down and they were bright metal, so I filled in one area that I just couldn't really reach with the top end still on, and just buttoned up it to see what's leaking now.

At this point, though, if it's still leaking, I'm probably just going to slather the thing in JBWeld from the outside and, assuming it holds air, declare victory.

oh yeah...a couple pictures...

I also built up and dressed the deck where it's chewed up in that last picture.

That last pic looks pretty good. I would call that doable. It would go even better if the engine were apart and on the bench for pre hearing and all that. It could be as pretty as you had time to make it.

Yeah, it would have gone a LOT better if the motor was torn down and the cases were on the bench. Like I said somewhere above, I'm doing this on the "Hard" difficulty setting.

It's still leaking, so it's going to get ground/wire brushed enough to be shiny, then slathered with JBWeld as soon as I can get to the hardware store and pick some up. At this point, I'm at least confident that the JBWeld will quit falling off, and even I have my limits.

Please kind sir never ever ever use any type of brake parts cleaner to prepare a surface to weld using argon as a shielding gas specifically. It can very easily turn into Phosgene gas and be deadly or worse, the debilitating effects of the exposure worse than death.

https://www.thefabricator.com/thewelder/article/arcwelding/cleaning-material-with-brake-cleaner-before-welding-a-risky-move-that-can-turn-deadly

https://grassrootsmotorsports.com/forum/grm/be-careful-welding-around-brake-cleaner/127201/page1/

https://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html

Wowza! Thanks for the heads up on that!

I agree that the weld looks cold and any degree of visible porosity is not good for this type of application. I am assuming you are using a spool gun with aluminum wire which I have very little knowledge of.

I have less experience with aluminum than any other process and it is very difficult to work with. It has to be very clean but do not use brake clean. I have heard that it is the chlorinated brake clean that is the dangerous one but there are better methods like acetone and then a clean water rinse and dry.

I do not think you are going to have success with a mig welder and spool gun attachment. The best process to use here is GTAW commonly known as tig or heliarc.

Here is a link to a case repair using tig. It is not hard and you don't have to be expert welder to perform these welds with tig but you do have to practice on some scrap and get a little comfortable with it. Also if you completely take it apart you should be able to take it to a machine shop and have them attempt a weld. No shame in taking it to soemone else if you do not have the specialized equipment required.

Very important to get back to clean base metal because the porosity you can visibly see gets further into the base metal where you can't see it and it will come up to the surface and ruin the weld you try to put on top of it.

Again I cannot stress enough how important cleanliness is to success with aluminum. After cleaning with acetone and rinsing with water and drying you can use a stainless steel hand wire brush that has not been used on any other material besides aluminum.

Hopefully you were using non chlorinated brake clean but I would avoid that as well. The links I posted are not definitive but the mix of heat, chlorinated brake cleaner, and argon in a confined space like in the garage with the doors all shut so the wind doesn't blow shielding gas away and you could be a very sick puppy.

Phosgene gas is one of the ones they used in WW I and really bad stuff, worse than death if you get just the right dose of it.

Yeah, it's non-chlorinated, but I'll go back to my usual brass brush+acetone from here on out.

I actually had too much airflow so the shielding gas was probably getting blown away as it was. The wind kicked up while I was working and I didn't bother closing the doors.

Don't use that brass brush. You'll only leave impurities in the aluminum. And i'll repeat what Mr. Skids stressed, use a clean stainless brush that hasn't been used on anything but aluminum!

CM,
My $.02.
The welds are cold - so its more like blobs of hard jelly filled balloons - leaving air gaps.
You need it hotter so it really liquifies.
This is more about the tool than the user in all likelihood.
Not sure its possible with what you are using.

JB will probably solve.
I was also really impressed with the lactite epoxy I used - super for heat and oil and grease.

Your other option would be:
1. Grind it back flat - but don't get rid of all the new metal - just thin it some.
2. Turn up the amps on your welder.
3. Preheat the area with a torch - so it wants to liquefy and run on you right away.

Or

Just slather some epoxy on it after giving it a thorough clean.

I could turn the welder up some more, I just...didn't.

In hindsight, I did a lot of stuff wrong to get to this point, starting with trying to do the repair with the motor in the frame. It was too windy in my workshop, so I wasn't getting full benefit from my shielding gas. I had a terrible angle to work with. This should really be TIG, not MIG work. I'm even more of a noob at aluminum than steel welding...the list goes on and on.

So with all that being said, I think I'm going to grind it down a little bit to give a smoother surface, then slather epoxy over that. The area that's still causing me problems is just too hard to reach because it's up under the reed block. Since I don't think I'm going to succeed without fully tearing down the motor, I'll wait until I have to do that to tackle it further.

You got a link to the epoxy you used, CM?

no shame in the epoxy game my dude.

you know what time it is, and that the proper repair is cases split and stripped, prepped, done did and then subsequently machined.

but, sometimes a little dab will do ya!

I suspect you got your settings dialed in on your practice piece after it got hot, then went to your cold bike. Preheating sweats out crap and gets thick material to a workable temperature. Looking at your repair pic, the welds get better as the surface temperature increased.

With a tig setup, you'd be able to boil out the contaminants before adding material. With a spool gun it's just wire. I use a similar method as filling a hole on sheet metal. I'll see if I can find something at my shop and post some pics on your how to weld thread.

BTW I'm on my third spool gun. Tried to go on the cheap. Ended up with a Spoolmate that cost 2x the welder.

Have you seen FMP's video? He intentionally breaks through

Yeah, I noticed (eventually) that once I'd had the weld running for a little while that the weld got better, but by then it was pretty well done.

Ultimately, I just couldn't get a proper angle on things to get at the top of the transfer where the worst of the leaking is.

I'll do it right next time the cases are stripped. For everything else, there's JBWeld.

Sooooo...I might have done a little rage-welding...

I wound up pulling the reed block off so I could get at it, but ran out of time because I had to come back in and jump on a conference call.

Other than the part where I can never tear the motor down again, I think I might have gotten it.

I ground it down, then hit it with more voltage and more wire speed and I finally started getting an actual puddle.

Time will tell once I can button it back up and try another pressure test.

That's actually starting to look like welding.

I had to turn that puppy UP to get it to that point, and there was a definite difference once the metal got warmed up as to how the puddle would form.

Fingers crossed, I may pull this off yet.

Whenever I read your project threads, I feel a sense of deep appreciation for the level of suffering that you are willing to endure.😌

It's only suffering if you don't enjoy it.

In the words of FDR, "A smooth sea never made a skilled sailor."

You're probably well past the point of just melting some solder in.

Maybe at some point I will consider buying a TIG welder if I ever do any aluminum welding. When I no longer had a place to store tanks for gas welding, I tried carbon arc brazing with an 80 amp stick welder. I also tried this stick shaker thing that was supposed to allow you to stick weld thin sheet metal. It would prevent the rod from sticking, but the welds were horrible. The carbon arc brazing was more workable, but just barely. I spent so much time trying to make it work. Eventually, I bought a Lincoln MIG welder.

Your spool gun welding looks more promising though.

I took one more run at trying to weld things up, but did not succeed. Ultimately, I ground it out from the inside, then JBWeld'ed to fill in the port and am, assuming that fixes it, declaring victory. I don't see the JBWeld ever going anywhere from the inside and it's backed by aluminum now, it's just rather porous aluminum.

I think, had I started with whole, stripped down cases, that I could have made it work. As it is, I'm tired of having a scooter down over this dumb thing. Tomorrow, I'll put it all back together and see if it's tight.

The only casualty of all this was my .5(?)mm base gasket. Everything else is fine. If I have something thicker, I'm going to up the port timings a little while it's open and I also noticed that I have a lip where the exhaust is at least a millimeter higher than the piston at BDC, so I'm going to fix that. So not a total waste of effort.

I can definitely see the advantage of TIG for this kind of work, though--the only option I had for going back over things was to add more wire, which wasn't necessarily what I wanted.

You ever get to the place where you need some help, I would be happy to sort your cases.