Modern Vespa

You just saved me a few hours of obsessing over the small channel - brilliant, thank you!

I think the seal was also a victim and not the cause of this failure.

That race should be sitting 1mm off the crank web. As you can see, it's obviously...not.

In your picture showing the gouge in the cases, is that how the fly side bearing was seated when you opened it up?

What I'm seeing is a crank/cylinder that were sitting off-true. I had a very similar experience last year on my GL when I missed a bit of weld spatter on the clutch side of the case deck. I can't find my post about it, but even being maybe half a millimeter off-true was enough to cause the fly side bearing race to work its way off the crank like that and push the fly side seal out of the case.

After I dressed the spatter off and repaired all the damage, though, it was fine, and that was about a year ago now.

Hopefully that isn't too scary to contemplate, but the fact that the race was pushed off the crank like that is the key indicator.

I've also gotten into the practice of cutting a slot as well. I happen to use a carbide bit on the end of my die grinder.

If not lubrication, it could be a twisted crank. Then buy a 60mm

Ooh...yeah... Done that one, too.

Check your crank is true, for sure.

Makes total sense - no tractors desired here!

Went out to measure the gears. Starting numbers:

Input Shaft: 12/13/17/21
Driveshaft: 35/38/42/57
Primary: 65

Both look stock, and it looks like the easy options are to change the primary drive? I see the Malossi or Pollini ones, but I'm a little fuzzy as to what they actually replace?

https://www.sip-scootershop.com/en/product/gearbox-24-63-teeth-malossi_20301000

This only has 2 gears plus the primary, do I then need to get the additional 2 gears to match up to the drive gears?

This feels like I'm missing a piece of the puzzle on how everything bolts together

Fear not the upgrade temptation I shall be googling away on that, thank you both!

Any starter tips for checking crank trueness?

Quick removal of the race - no problem with the bearing splitter. Definitely had some sealing compound gunk applied that came off with the race.

I did a visual check of the crank (video link) and it looks pretty straight, no hiccups / catches in the rotation and gaps remain pretty constant. I'm hesitant to pull the crank if not necessary as I still fear the reassembly.

https://youtube.com/shorts/kB2Qfa1_yPA

Re-reading your advice here CM & rethinking everything. The pictures were showing "as found" condition. After removing the race, there were no obvious signs of debris / gouging on the crank other than a rubber / silicone film that was on the back side of the race (??) and wasn't visible until the race was pulled.

Can you clarify what you suspect is off-true so I can continue investigating?

The crank itself is twisted?

Or the fly-side bearing position in the case is not aligned axially with the clutch side?

I'm not sure what can happen on these engines. But here is a rough-go at a summary so far:

The engine was put together fairly well (professionally), never really run (~50 miles from owner - who knows) but it was running lean (because of a covered oil channel toasting the bearing and shredding the oil seal) which overheated the piston / piston rings (air leak causing extreme leanness) leading to loss of compression.

But if I understand what you're saying, it may be that the race coming off of the crank-web is another clue, it doesn't quite fit that narrative and it may be a crank that is not true axially towards the fly side which put additional pressure on the bearing, working it out towards the seal, blowing it and causing the air leak, etc... Is that directionally correct?

Ok, got it - the "up gear" kits with 2 pieces are the for two separate areas - the primary gear / cush drive outer & the clutch side.

The Scooter Help explainer was invaluable here (pic) & for future google-fu

https://www.scooterhelp.com/tuning/vespa.gearing.html

Also, this calculator is the best for me to play with available options -

http://gearingcalc.free.fr/

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Edit - it looks like the best gear ratios / rpm range comes from the BGM or DRT "extreme long" kits. Anyone have experience with either of these?

https://www.scooter-center.com/en/clutch-sc-largeframe-type-cosa2/fl-for-primary-gear-bgm-pro-62/63-tooth-straight-vespa-px200-rally200-25-tooth-sc6225

https://www.sip-scootershop.com/en/product/gearbox-25-62-2-48-teeth-drt_16020200?q=62%2025%20gearing

Or for laziness sake, just moving to a 25 tooth clutch seems to get me most of the way there.

62 / 25 ratios: 11.78 / 8.01 / 5.56 / 4.24

65 / 25 ratios: 12.35 / 8.4 / 5.82 / 4.45

Can't wait to hear the wisdom / experience on this - reading past posts seems to point to very strongly held points of view

Crank looks like it could be twisted. The twisting is the two halves against the big end pin. There is lots on YouTube. Here is one from everyone's favourite Norwegian

Very useful, thank you! Video watched, (sort-of) absorbed and tested using a bicycle truing stand. Then again with a homemade "redneck" stand and caliper.

Appreciate you & CM taking a look and seeing what you think: https://youtube.com/shorts/IgPPC0tXpPc

Using the calipers to measure for pinch, spread and axial trueness, it appears to be dead-on from what I can tell (pictures attached).

Also, there is some bearing rub (?) on the inner side of the crank. Is this normal or a sign of improper installation? (pic)

Lastly - now that the crank is out I can get a better look at the inlet pad. It looks pretty shady, is this within spec? Or am I too used to seeing everyone's really clean engine builds on here?

Crank doesn't look so bad now it's out. With a dial gauge it will show some error, how much though. Rubbing on the web is not great. Cranks have been changed for less reason.
Has that engine ever been on holiday to Asia? Rotary pad is not original. And not pretty. If you were to do a reed conversation, there would be few objections.

Whew - good to hear! Will try to track down a dial gauge, another reason to dive deeper into lathe machining

It is supposed to be a no-expenses-spared build by a reputable well-thought-of local builder and confirmed by him in a conversation. Giving him the benefit of the doubt, maybe the PO didn't want to spend to fix the bodgey previous repair?

Debating on shelving this one and just tuning the original VBA 150 motor. With a crank, cylinder / piston and gearing changes, the p200 motor is looking to take as much $$ to get on the road as the original. Maybe I just get this one back to light-duty running with a new piston & seals and save it for a future around-town scoot. At least the rotary pad looks decent on that one

Looks like there was some welding on the rotary pad that didn't hold. There looks to be extra material where the crank web fits. I have a VBC engine case that has a similar fix, though it was a much better job. Welders and machinists who could do that kind of work were much more common in the US at one time…some more skilled than others. We associate that kind of work with SEA. Some of it can be pretty good.

Yes, that case is a candidate for a reed valve. If it were mine, I would give it a try because I couldn't make it worse. JB weld is probably not great for replacing chunks and that pad looks like it might shed some more. Welded metal appears bonded to the old pad but not to the case.

Is that the "no expenses spared" engine from CL?
Al did the rotary pad repair and small world if so.
I took a pic of one of mine before an epoxy repair. Looked worse in the photo vs in person, and worse than your photo.

Some "if I were you*"
*This is just what I'd do vs advice.

Return the kit. A kit isn't needed for what you want.
New set of rings and see how it goes.

24 tooth(helical) Cosa2 clutch for a 65 primary. Should get you close on 8's without any other gearing changes.

Check/true the crank* with a dial indicator, following the video Jack221 posted. It's fun to do. Inspect/replace the main bearing. Upgrade the seals.
*That scoring is from a metal seal that slipped out in it's history.

Electronic (DC) ignition kit.

Ha - yep! I spent some time talking with the PO & also with Al This is perfect and very helpful at the moment - thank you both! I will continue to formulate the plan and post here before I get too carried away

How carried away do you want to get here? Because you have options, some of them tame and some of them...less so...

Says the Wild Child of the bunch!

My heart says all the way. My wallet says slow your roll


Thinking about performance priorities and re-evaluating after learnings so far. Creating a spreadsheet now (that I will need all y'all's help fine-tuning) on the pros / cons of both paths.

Okay...so here we go...in order of Extreme-ness, from least to most...

1) Take a shot at fixing the pad with JBWeld. We've discussed it above. I've done it on worse-looking pads than that and those motors ran for 10+ years without rotary pad issues.
Pros: Almost free; will almost certainly work; Nothing changes
Cons: Underlying rotary may break loose; Harassment by anti-JBWeld partisans; lingering fear of eventual pad separation/failure

2) Try an in-line reed block (see Wrecked rotary fix. Anyone tried these?)
Pros: Minimally invasive; Just needs a flowed crank
Cons: Questions about how well/if it works, plus how much modification is required

3) RD-350 Reed block -- Install a little more serious reed block. This is a basic manifold. How much benefit you're looking for is (in theory) a function of how much of the cases you're willing to grind out for intake flow. Reality is that this is just one upgrade in a long series, which can be super-fun, but also will probably leave a trail of destruction as you make mistakes, learn (at least in theory), and push parts past their limits.
Pros: Fast, fun bikes; challenging engineering problems; Builds useful Life Skills like "hiding deliveries from your Signifcant Other"
Cons: Cost (will need a side draft carb, too); Probably will lead to at least a new crank, upped gearing; Risk of death going 70 on 8"s; May lead to addictive, speed-seeking behaviors; Did I mention cost already?

Extremely helpful and gives me confidence in my research as well. Thank you!

Option 1) I do not like, reminds me of my childhood redneck wrenching days. Works, but will most likely need to redo all the effort in a short time and costs more in the long-run than the better solution. I am more than a bit leary of correct case fixing after reading Charlieman's saga / mill purchase.

My take at the moment is: If the crank needs to be replaced, then reed isn't that much more expensive (slippery slope but :shrug:). That leaves 2 & 3

This means crank trueness is the guiding light. I just took a baseline measurement using the dial guage and it looks like you and jack are insanely eagle-eyed. The crank is off by 0.0025in / 0.0636mm

Baseline video here - https://youtube.com/shorts/tpyGRClYdYg

I am now going to go hit my crank with a mallet because some guys on the internet told me to follow some Norwegian guy's basement video. The scooter world is a strange place

I see nothing wrong with this plan.

But if you decide you need a new crank...we will talk...

And it worked! - maybe I'm the luckiest guy in the world, but 2 solid whacks as described by aforementioned Norwegian basement guru and the crank is completely true

https://youtube.com/shorts/j1vA9uC25_M

Holy smokes, very cool, you all are amazing!

This quick fix does put Option 1 - jb welding / smearing - back on the table.

You're good at this. Crank is now straighter than a new one.

Option 1, unless your partner's birthday is in 2024.
2 and 3 are cans of worm$.

Dig into the archives to see how to do it correctly, using SocalGuy in your search.

I still can't believe you and CM spotted it!

For my curiosity, I had a look at a service manual that a MV member posted:

http://oopsclunkthud.com/Vespa_service_manual/Pages/227.html

Not sure about the P200, but the VBA / VBB would have been in-spec (pic).

Crank is carefully set aside and the JB welded pad is curing. This episode still has me re-thinking original VBA motor vs P200 upgrade...

Work is getting in the way, but some progress and finally ready to get an order going.

I am leaning towards switching back to the original motor for this project. There is a ton of info in the archives on the VBA upgrades but I'd love to see if I've got it somewhat right. Specific questions bolded below.

VBA Motor Upgrade Shopping:
* Crank
old one is rusted / toast, thinking Mazzu 60mm? - https://www.scooter-center.com/en/crankshaft-mazzucchelli-racing-rotary-valve-60mm-stroke-px-flywheel-taper-vespa-sprint150-vlb1t-gl150-vla1t-gt125-vnl2t-gtr125-vnl2t-vnb-vba-vbb-t4-super-7676246?number=7676246

* Cylinder Kit - Looks like I can get a deal on a Pinasco 177, is that still good for 2 ports?

* Primary Drive Kit

* Bearings / Seals / Gaskets - any preferences? The SIP Kits seem like an easy option

* Bigger carb - SI 24?

* Clutch / Clutch Plates - BGM is out of stock, SIP Strong are $$$ - is the Scooter Mercato 7 spring Banded Basket w/ Malossi / Newfren plates a good option?

* Mounting Bushings

* Ignition Kit - with the px crank I can just use the existing P200 setup right?

* Clutch Spacer for Cosa / strong clutches - https://www.sip-scootershop.com/en/product/spacer-sip-cnc-clutch-cover_17650000

Am I missing anything? Thanks in advance as always!

The pinasco is the best kit you're going to get for two ports. I have run one myself on my 2port VBB motor.

20/20 is all the carb you'll need. The kit just can't draw enough mix for a 24/24. If you go 24/24, you'll never get the midrange dialed in.

You can stick with the six spring clutch. You're not going to get enough power to break it. New plates and you're good to go.

Scooter mercato have a rebuild kit that will have all the bearings/seals/wear parts you need.

No need to go crazy on any of this. It's a two-port.

Noted & appreciated! SIP has a "largeframe tuning summary" that pushes the 24 / 24 but you are now the 2nd experienced tuner to tell me to stick with the 20/20. Did you go long stroke on your VBB? Any tips / adjustments for the 2 ports?

Pinasco purchase in process!

Digging back into the archives - 7 springs for the VBAs were recommended pretty highly with the clutch spacer. May be worth it if I end up playing with the gearing?

The reason I tell you to stick with the 20/20 is because I tried the 24/24 and could never get it to set up right. It just doesn't draw enough air at lower RPM's for the 24/24 and the SI carb lacks the options for tweaking mixture like a side draft, where you have a massive range of needles for the 3/8 to 3/4 throttle range.

While it won't hurt anything to go with the 7-spring clutch, you'll need to snap off the oil guide in the cases. I can tell you from experience, though, that I put ten years on my VBB's motor with a Pinasco 177 and the OG six spring clutch and never had any issues. It's just money you don't need to spend.

You'll need to sort out the port timings. You're going to want to keep them pretty low. TD 120, I'm thinking. So like a .5mm, maybe 1mm base gasket, then adjust squish with a head spacer and get it down to 1mm.

I'll assume (and recommend) that you not extend the intake timings, other than maybe buying a cut crank if you haven't already pulled the trigger.

Also, what exhaust are you running/going to run? Some sort of box, I assume, but which one?

The Polini box will give you low end torque, but runs out of rev's pretty quickly. The RoadXL will interfere with your centerstand and require a side stand it you go that route (that's what I have on my VBB now). The SIP Road3 will give you more top end rev's, but will be slower into the power than the Polini.

You can get a respectable build that'll get you to 60 MPH if you do it right, but it'll be pretty wild feeling if you don't throw even more money at the suspension, wheels, and tires, so consider what you're signing up for before you commit.

My memory is that the VBA has a very small intake opening, anybody care to comment?

Dude - this is amazing, perfect advice! Would you just go to the side draft right away? I am all for not spending extra money As I am pretty fresh to this, my plan was to measure everything as a dry-fit to really understand the theoretical - it's a little fuzzy at the moment. Not bought yet - was looking at the Mazzu 60mm stroke w/ px taper - https://www.sip-scootershop.com/en/product/long-stroke-crankshaft-mazzucchelli-sip_45135600 but very open to suggestions Not bought - but you are making a great case for Pollini I'm in

Definitely feels small - I am happy to adjust based on the final timing numbers. After re-reading Hibbert's epic thread on flowing his 2 port bajaj I will be sharpening my dremel!

I love my polini box, I'm not a high rpm guy. That said I've hit 70.4mph with it, different top end though, I run the VMC1717. It does foul the center stand though. Had to get the relocation bracket from mrp to get it on.

I have that same crank in my VBB, including the PX cone. Any time I can, I swap to the PX cone so I don't have to maintain inventory of large and small cone ignitions.

Don't worry about extending the intake opening for now, but definitely get it as wide as you can.

For the exhaust, either SIP Road3 or Malossi will treat you well. People tend to favor one or the other, and Ray8 is a big Malossi fan on his VBA.

I have a SR3 with my Malossi 210 and it's a good pairing for a mildly tuned motor. It added a few hundred RPM's of top end versus the Sito+ that came with the motor.

There are several threads/posts on here that cover port timing measurement methods and expectations. You're going to be looking for peak power at about 6,000 RPM's or so, which means 120-121 TD/160 ED/20 BD. (Transfer Duration/Exhaust Duration/Blowdown).

There's only so much you can do with that base motor, so don't try to go crazy on it. If you want to do that, start keeping an eye out for a Stella/LML reeded motor and you can build something crazy on top of that. That's also when a side draft carb might make sense. Definitely not on this build.

When I did my last VBB tune, I wound up with 123 TD, then got a little overexcited with the Dremel raising the exhaust port and killed the cylinder.
So I'd say if you're wanting to get aggressive, you might square the top of the exhaust port, but don't raise the port height any.

Nothing we're discussing here is particularly risky so long as you don't go too wild on the intake. More a matter of picking parts that work and play well together, then assembling correctly.

Which ignition are you looking at, btw?

it may be too late or maybe I'm off the mark for reminding but you need the 2 port pinasco 177, not the 3 port.... just making sure you understood.

Or the welding & machining skills to build up the aluminum on the cases, then deck it and cut a third port into it.

ease him in chandlerman, ease him in

However, if buying a new crank. And if its a long stroke with a longer (110mm?), conrod. Then, a fat (6.7mm?) base packer can be added. The third port can be cut into the packer and barely touch the 2 port casing.

This gives you the option to buy any 3 port kit you like. However, (again) your cases don't have a retained main bearing, so really a high power kit is not a good thing, as it will axially strain the big end. Anything under 20bhp is most likely fine.