Modern Vespa

Another (but expensive) option is the Parmakit crank for their 'sixty six' 205cc kit for the 125/150 motor. I think the case still needs some fettling for this option:

https://www.vespatime.it/en/engine-parts/crankshafts/crankshaft-advanced-parmakit-vespa-px-pe-125-150-stroke-60-connecting-rod-110.2.20.100.gp.6109.uw

Ooh - some good responses.
108 - thanks for the info.
Jack - I don't mind just yanking the motor this time - I'll get a good look at everything and have the shop all cleaned up and ready for a bit of inspection work.
I will start the tear down soon and we will figure out what's spitting shrapnel at us, and if Whodat is gonna pass and graduate using his time honored approach.
Some kinda bearing cage has my vote/ but could be anything.
Not as good as riding - but keeps the mind nimble(ish).

As for the P200 crank - shaving off the rib is an option - but I would like to harvest the wider web for optimizing the inlet width.

I have kinda this whacky idea that I could machine the cases myself.
It involves melting drill bits on crank shaft webs.
More on that to follow...

PREFACE: This is a whole lot of bench racing and pictures that may never come to fruition - but I have to wait for my parts from Germany - and you have already looked at all your YouTube videos and doom scrolled Facebook. So here we are...


Ok - little bench testing of some ideas.
When my parts get here - I need to machine both halves of my cases.
I have a couple ideas on how I might - so I experimented today with one of the steps.

The concept is:
- Take an old crank shaft apart.
- Take down the bearing journal enough so it will just slide in and out of a bearing without being pressed.
- Weld - using tool steel - some bumps on to it, then shape those bumps in to cutting edges.
- Make jig (still to come) that keeps it level - put it in case half - and spindle out the groove on one side - and the wider circumference on the other.

What could possibly go wrong?

So step one is to see if I could weld some tool steel to a crank, and cut it in to a cutting tooth shape.
Hmmm - where can I get some tool steel?
Well - how about one of those old drill bits I have lying around!
Shockingly - it works.


Dirty old VBB crank - pressed the pin out so I had the two halves

Cleanded - then chucked it up and spun it in my "lathe" with some sandpaper to take down the bearing surface enough so I could...

... slide a bearing on by hand without press fitting

Checked fit in P200 cases. Slides in nicely without wobble

If I can build it up here with tooling steel, then shape it to have a cutting edge - then maybe I can spindle the slot in my cases...

Set up my tig so

cleaned up an old drill bit for my filler rod

Made some random welds in different sizes. Didnt really know what to expect. worked my way to about a 3mm tall tool steel bubble.

Then ground one into a cutting shape. The idea is to have a row of them. Edge is sharp and hard as hell - it will certainly cut aluminum. The question is - where and what parts of the aluminum...

Really nice idea. Like making a fly cutter. Tooth angle I feel should be lower. Don't want it to cut too quickly.
The tricky bit will be near the rotary pad. Need to extend it sideways, while matching the existing surface. Sure it's possible but a delicate situation.

Thanks.
It literally is a fly (wheel) cutter...
Good points.
The pad will be tricky - but if I can make a jig that holds the cutter very steady - then I should be able to do it.
My idea is to index the cutter off the cases by making a plate that bolts on to the cases and has a second bearing in it.
This way - the case bearing will hold the cutter from below, and a second bearing on the plate would hold the cutter's shank from above.

I will practice on some cases that are trashed - before I try it on mine.
Agreed - my cutting tooth angle should probably not be so aggressive.
Good thought.


The cranks all have this center hole - which I can use to center a shank that will run through a plate & bearing before attaching drill

This needs to be a discovery special...

Crazy cool stuff to watch.

Like it. Reminds me of a grinding experience involving a clutch cover and a router back on page 10 or 11 ...

Definitely need video of practise cuts...

Super interested in seeing how it plays out...

To boldly go where no one has gone before....

Gracious - I hope not.

Went to see my machinist today to beat this plan around with him.
Positive note - he didn't kick me out of his shop.
Chuckled - said he thought it would work - and suggested rather than building up with weld/ grinding a cutter - I could use square high speed tool stock.
Gave me a piece of 3/16 that seems to be about the size of the groove.

I like this approach. If I can figure out how to clamp it in snug - I will be able to adjust its position, and I could use the same tool to cut the fly side larger circumference by just using the other end of the high speed steel and shaping it to cut side rather than under.

He told me that for aluminum - I would want to have a 7° back cut - so it kinda feels official now.
Miscellaneous experimentation below.


Made a first cut on my donor crank tool

Then scribed a line so I could cut it just larger than the square high speed tool stock he gave me

Hacked a few more cuts - may be the straightest 3 cuts of my life.

Picked up some beer and a proper size drill for a 4mm tap I have

Drilled some holes to allow clamping screws

Over drilled top holes so tap would fit through and then tapped holes in crank

Made in vain attempt to anneal to see if I could soften it so it would clamp - not really...

Here it is. I haven't ground edges on the tool steel - but that's the easy part. It doesn't clamp properly - so I may need to make the tab longer - or re-think how I am clamping.

Super excited about this, maybe because you'll be able to repair the pads if need be...

I’m no expert at this, but as for clamping, perhaps the grub screws should go through the blade?

Grub screws through is solid.
I thought I could get it to clamp without having to drill through the tooling steel - cause it is WAY hard.
But my method didnt work...
What shocked me was how damn stiff it is - doesn't even budge when I tighten the grubs where I have them.
I am going to try and use them as just pinch bolts right on the part - to see if it both locks - and will allow easy adjustment.
Need to have subtle control over positioning as well.
If that fails - I will try drilling the through holes.

The crank - while stiff as hell - is not bad to machine or drill.
Might try and cut a practice case tomorrow... Will see.

Took a bit longer than expected.
'cause I snapped three (THREE!) taps in one of the holes.
Each time I had to cut it out - and rebuild the area with weld material - re-shape - drill - tap- snap tap - repeat.
Patience officially tested.
Realized there was a void that the taps would catch on and no matter how gentle - Caaaa-RaaaaCK!

It's close.
I may add one more component to ensure it centers well.
I also have to shape the cutting tool.

Hope to carve a case for practice this weekend.
Will be interesting to see if any of this works!


Drilled out the center - the factory left me a pilot hole

TIG'd the shaft once inserted - using 123 blocks to keep it as square as possible

New grub screw set up visible and cutter installed

Beauty shot

... If this works bet you could modify it to lighten flywheels

Just in case you can get off the shelf bit for a lathe.


https://www.ebay.com/itm/1-4-HSS-Lathe-Form-Tools-Set-Of-8-Pieces-Square-Shank-Lathe-Pre-Formed-Tools-/164304017321?_trksid=p2349624.m46890.l49286

Ok - so finished my the version 1 (V1) of my cutting tool - not to be confused with Malossi V-one. Trust me...

Meanwhile - Rowdy dug up an old thread on resurfacing inlet pads - and I got my hands on a set of spare bodge cases that match mine to take a closer look.

Net result of all this: the tool I built will probably work to cut a groove - but lacks the precision I would like to have.
Additionally - I wouldn't trust if on the fly side of the cases to cut that cavity wider.

Now - at this point some of you may be spitting out your beer yelling - no shit! - at the screen, however:
A. Your wife's not gonna be pleased with the mess.
B. Goal here was to try and figure a home remedy - patient isn't dead yet.

Tolerances on the pad are .05 - .1 mm of clearance (.05!!).
Wholly shnikeys - that's not alota wiggle room to work with.
Have re-jiggered my plan - and ordered up about $68 of parts from Amazon and another $20 from McMaster-Carr.
Will see if it puts me in better position.
Shipment notice says at least one of my packages has left Europe.
Clocks's ticking.
Pictures of V1 proto below.


"Lathed" a piece of 1" DOM tubing so it would be a slip fit with my stock main bearing

Cut it and "pressed" (read: hammered) it on to the crank half so that I could have an elongated section to slide in and out of the bearing to allow plunge cut as per Voodoo.

Tool now in cases - cases clamped to table - top plate with bushing slipped on and bolted down to case to center. The issue is - my spindles are just not straight enough to hold .05mm of tolerance... Back to the drawing board.

Video of it cutting, or it never happened...

Just jk... i'll be sending my cases to you soon!

Oh, off on a tangent, figure out what happened to the kryptonite shards?

From the crank?

I haven't torn my motor down yet.
Was lucky enough to get a loaner set of cases to experiment with.
Gave them a quick scrub - cause they were a wreck - and found they were true bodge.
Have been told about how its common for the brass main bearing seat to get peened to keep it from spinning.
These have that.
May try and give these cases a little restore as I warm up.

Close look shows that they were peened - but also - someone must have put a P200 crank in there! groove has been naturally worn.
Suspect putting an abrasive and some liquid in - then just spinning the crank would cut a pretty nice groove! This one is only surface deep.

Huh new season and a whole new adventure , awesomeness at its best.

Well - on a positive note - I didn't trash the cases.
My first cutting tool was just too in-precise.
Rowdy dug up an old thread about repairing the inlet pad - and it really highlighted how tight the tolerances have to be.
.05mm - 1mm is the target clearance on a perfect pad.

Voodoo made a good suggestion about using existing cutting tools, and figuring out how to index the adjustment - for fine changes.
I took him up on that and found a cheap bearing head - $30 on amazon.
With a little cutting and welding - and a few precision bearings and rods from McMaster Carr - I was able to make a jig.
Took some doing.

This afternoon - after I was able to spin it and hold tolerances of .05mm with a feeler gauge at all points on the inlet pad - I gave it a run on the bodge cases I have for experimenting with.

Results were promising - though I'm still not quite there.
Good to have some practice - and I will make some changes.
Pics and a little video below if you wanna see.

Changes upcoming:
- Move the rig to my drill press which will more than double my RPM - the little drill is moving too slow and hard to control.
- Shim my rig - I should have used the feeler gauge under the cutter as well as between the side and the case.
- Cutting oil! Why make it harder than it has to be?!

I will shim and move to press tomorrow - and see what kind of results I can get in evening out the depth. Think I should be able to get it pretty darn close. Will see.

BTW - was our logo always red - or is someone in Texas going whole hog with their project?

https://youtu.be/eOYpof7CVYU


The cutting tool - This goes in the little jig I built

The set up - before I welded the jig together. I used some cylinder studs to for the jig

The set up - just after the first action. Making chips.

Results - so so. Groove is about .5mm deeper on one side - will need to ship to level. Inlet pad was ever so slighly grazed when tool came loose - but imperceptible to finger touch. Note to self - tighten tool.

I like it, looks like fun.

How about using a drill press without that jig?

Christopher - I am having some fun.
Ray - Good thought - I tried the drill press - but there were two issues.
1. It spins the wrong way for my cutting tool
2. It just cant hold the tight tolerance of my jig. I mean - I feel like I need to wear shrapnel protection when it starts to spin. The entire press is overwhelmed with the wobble from all the weight of the cutting head.

That said - I took the steps I thought might help - and it was great.
- Used shims to level the cutting
- Pulled out a much bigger/torquier drill

What. A. Difference.

Cuts really nicely.
Should have filmed.
Went through like butter - happened really quickly.

Few pics below.


New set up, twice the RPM and power. Huge difference - just cleanly shaved as it turned.

"precision" shims under the leg on the left. You can see I used red sharpie to see where I was hitting and even things up. worked quite nicely.

End results - this is just a test case - but it came out nice. P200 rib crank web lip should fit

Nice jig, awesome to see it.

Fabricate more for sale? it'd work for a rotary pad repair right?

Cant find a machinist to work on the 0.05mm crank to rotary pad clearance.

Everyones like, "so how much you want taking out?"

i can take my sweet time with a setup like this...

Great job! Surprised how well it came out. You have a close up of the rotary pad transition?

You know SIP will be selling a copy of your tool in about 6 months and fitting 200 cranks as default.

Amazeballs.

And Jack is probably correct. Available at SIP in 3-2-1...


(oh... That is the OG logo.. done all by El Jefe Jess. Any programming, infastructure and whatknots is all him.)

He also fixed the youtube embedded for chrome issue! Don't need to post urls along with videos anymore.

Yes - but will it be a class A repair is the question.

Results were better than expected.
The rig is a little bodgey - but hey - we don't judge here.


Rotary pad transition:
Good question - I'll post some pics later today.
I have the cases bolted together currently - working on my welding...
The gold standard method here would be to do a little build up on the rotary for repairs and simultaneously re-surface it so that there is zero step up or back when the groove is cut.

I set my cutter up to have a .05 clearance - so I would expect a very slight positive step.
In pic below - I've zoomed in - this was shot yesterday before cases were re-assembled.
Looks like there is about a .02 - .05 step as would be expected.
If I don't do a build up and cut down as noted above - I could perhaps use some gritted rubbing compound or slurry of some kind - and lap it in with a crank web. I'll take some measures once I have a crank properly pulled in.
Crank off at a tooling shop where they are grinding the journals (theoretically) to match VBB config/sizing.




Magnified - this edge here

Missed a couple:
1. Wait - am I imagining that the logo was previously black - or is Jess sending you a subliminal signal on paint color.

2. 108 - gracious - I have two paying jobs, so not really planning on going into business... Might fix the random case that shows up locally - provided it is clean enough to eat off of when it arrives - and there is something to drink...
- what parta the world are you in?

How well I can repair and re-cut a pad is on the to figure out list.

I smell royalties ...

Black? Are you sure? Are you huffing sealant again?

I kid... Logo was black and grey and the "banner area" was also black. Jess is fixing up the creaky floorboards and dusting corners of the forum. He reverted to the original color scheme, but I like your idea better... him pushing for that OG red anyway he can. *snickers*

what's your point? I'm married to a European family that speaks in obliques and subtitles. I'm like a Labrador retriever - happy and energetic/ to their refined and cutting.

I once heard my mother-in-law say: "I really like the brother!" at a dinner. It took me years to realize it was a shot at me! Love her. Funny as hell - you just gotta work to keep up.

That logo is a statement - just sayin.

So... about that welding.
The other thing I am working on as I spindle out my cases - is how to weld cast aluminum.
A quick check of the internets will tell you - it's tricky.
And there is some truth to this.

Turns out castings are full of - well - no one quite knows.
They mix stuff in to the parent material.
It can also be porous - so 50 years of oil soaking doesn't bode well either.

I've watched alotta u tube - so... what could possibly go wrong?
Took my first stab at it this weekend. Started out rough.
had to grind it back more than once... but feeling pretty good about it now.

Am no expert - but results are pretty decent.
Few pics below.


That my friends is a VBC case with solid thick port walls. Those little holes are where some contaminates boiled up in the metal. F*king bear to fix - but Im tryin'

Here is the top of the other side. These were tricky because they are so thin. I will need to surface the entire cylinder mounting surface.

Welding looks great...

I'm not welding myself, I took my cases to a guy who welds, the work that came back was shocking... looks like swiss cheese with ALL the holes... at least it'll be better than my epoxy welds...

Im currently in HK, Asia with the damn wheel locking PX200... but I'm long overdue to be visiting the OC to pick up parts for another build... I'll be in you part of the world hopefully soon!

looking good charlie

Those welds look good to me

And definitely better than my welding, which is JBWelding.