Modern Vespa

No, the red/white/green are all you need for it to run.

Did you check for any bare wire that could be shorting to ground? I've screwed myself up by letting the wires rub on the flywheel, at which point it grounds out and stops running.

Assuming it's all still installed, I think you can disconnect the wires from the CDI and then test each one for continuity to ground to identify a short. (Someone correct me if any of them *should* have a path to ground, please! )

And can you confirm you previously checked flywheel magnetism (should be able to hang a 19mm box wrench off it) and that the plug wire connectivity is good?

Ok, perfect! I am learning (slowly).

Short is always possible, will test. I'm going to head out to remove & test magnetism (had not previously done) and take some pics of the stator. I also have a plan to disconnect anything extraneous that could have a short (rectifier, kill switch) and build up from there.

as they say, ad victoriam!

Ok, magnetism checked - seems ok

Also a few pics of the stator, no obvious issues from what I can tell. Trying to isolate potential shorts and will report back more soon.


Holding an SAE equivalent wrench - seems ok

Stator front - no obvious shorts or signs of distress.

How are the wires on the stator? Are they original?

Reason I ask is even if the wires look OK they can still be all crusty. Did you take the stator out of the engine?

Just trying to get an accurate picture of what you've done, and haven't done.

I got the motor with a little history - it was rebuilt professionally about 3 years ago and supposedly with all new ignition components (along with a lot of other stuff).

I did take the stator out and it looks pretty clean (pics below) but definitely not sparkling


Back of stator

Closer view of front

And you're *sure* the plug wire isn't pulled away from the terminal, but still held together by they boot, on both ends?

I'm going to keep asking until you confirm you checked, because it's about the third most common cause of sudden No Spark.

Also, the wires on that stator look more than three years old to me, but maybe they're just greasy. Did the motor have a bad fly side seal when you got it?

Ya, definitely sure - I also used a fancy "harbor freight" in-line spark detector and it lights up, but is weak. Looks like it is just not putting out enough voltage? I checked on original cdi, will now check on the new cdi unit to see if it performs the same way. I agree - no leaking fly side seals, very clean. Maybe just reused an older unit? Any common issues with an older unit putting out lower output?

Quick update - both CDI units produce very low spark. I even swapped cables (and made sure they were tightly screwed in) to see if either were a problem. I get some voltage, but just enough to make the test bulb flicker.

At this point I am guessing it is something stator-related and the easiest route will be to get a new system. I've been leaning towards the SIP Vape DC ignition and followed a lot of installs here. Seems like a good option and not terribly much more than just getting a new double-yellow stator.

More to come - will continue to work on buttoning up the rest of the wiring and cosmetics while I wait

Hey Plantguy,

If it was mine, this is what is do....

1) Tank cleaned, Fuel tap replaced, fuel hose replaced, carb rebuilt.
2) new plug, new wire.
3) change gear oil
4) splash some premix in it and kick it over, 9r bypass tank altogether and use a small hose and temp tank ( a syringe?), connected to the bango.
5) is it getting fuel?
6) is it getting spark?
7) shoot some either or quick start directly into the carb.
8) can you smell the fuel?
9) Push and bump start it

If it's still not even pretending to start, I'd check the ohms of the stator itself. MJRally created a wiki page for that.

Stator Values Wiki

And I'd check at the end of the wires where they connect.to the junction box and CDI. One of those wires may be faulty causing all the issues.

Good luck...

I just saw your response. Very low spark. I don't get.that. I've messed with a couple dozen engines and never had very low spark.

New wires soldered incorrectly to the stator - yes
Stator values out of whack - yes
Stator not set properly - yes
CDI dead - yes
Plug dead - yes
Low compression - yes
Plug wire and or cap connection faulty - yes
But never very low spark

It there is even a little spark, it should kick. I'm anxious to see what fixes this issue, especially since it was rebuilt by a professional three years ago....

Hmmm, it's a mystery

Final thought for the evening...what's the compression on this thing? If it's below about 90 PSI or so, it's never gonna run right.

And have you tried hitting it with starting fluid? That'll get some joy, even if the compression is marginal or the carb/fuel is not there.

Good to know, thanks QS! It doesn't help that this is my first build so everything is a bit new in this world. The motor was running (according to seller) before it was removed for an electric conversion. So if we assume the wiring is correct but maybe the wiring / coils have aged out or I managed to screw them up during attempted starts we have one possible issue.

I've got 1 new cdi unit, 1 that appears to be in good shape, new cables, new plugs so we can maybe rule those out?

I could be missing something on the connections, but have checked each one pretty well. The motor kicks over nicely and the fuel is flowing when the tap is open (new hose, new tap, new filter btw) - can visually see the slide getting lubricated. If this was a older car, I would focus on the distributor / points but there doesn't seem to be a lot of options with the Vespatronic / Ducati. Appreciate helping me track this down CM - haven't checked the compression yet or hit it with the "starting fluid" but will do in the AM.

My paths to investigate:

* Could the timing be off enough that it wouldn't start? I haven't mucked with anything but maybe it got bumped at some point?

* Verify that the CDI is getting voltage when kicked

* Remove stator again and check the continuity of each coil. Not sure of the impact if 1-2 coils went bad (is that even possible?) but might be a lower overall voltage? Maybe?

* Test cylinder compression & hit with ether

We've all started from somewhere, and it's all good.

These engines were made to run with crap gas and crap oil, and should start with a bit of persuasion.

You list looks good to try. You don't need to remove.the stator, just get to the wire ends to check the ohms of the coils according to the stator you have and the link to the topic about the stator values wiki above.

But try the ether first. Forget all the other stuff. Hit it with ether and get it to cough.

One time I was sure I had an electrical problem and spent hours looking for one. Hit it with ether and realized it was fuel related.. idle jet was clogged. Crazy....

Well, the good news is we may have the root cause. Bad news - compression test only shows 80psi.

Took the scope out and the piston looks pretty pitted ( and has a weird 6.9? stamped on it) - any thoughts on this? Cylinder walls look good and there isn't any obvious slap / movement between the piston & cylinder wall.

Is the plan to fix compression just gaskets & piston rings? I'm thinking about replacing the whole piston while I'm in there. Is it worth it to get a new cylinder at the same time?


Top of piston with weird stamping

View of the cylinder wall / piston interface


Last edited by plantguy on Thu, 02 Mar 2023 07:03:51 +0000; edited 1 time

Have you tried starter fluid anyway? What do you have to lose...

Not yet! Excellent point

perform a "wet test". Squirt some motor oil down in the spark plug hole, then take another compression test. If the PSI is a lot higher, then there's some sort of problem with your rings.

Squirted a bit of oil and got it up to 85, did 2 more squirts and it went up to 95. Definitely looks to be related to the rings. Big gap / missing a piece?

If I'm replacing the piston - should I just bite the bullet and get a new cylinder kit?

Will pull the cylinder later and give a full report

My personal thoughts on cylinder kits are WAAAAY different from the average person. Reason being is that i commute on my scooters, so i want absolute longevity and reliability with my engines. My opinion is if you have a stock 200 engine, then i would keep it stock. If you have a 125/150 engine, then i would either kit it or swap in a stock 200. My personal solution for any of my scooter is to swap in a 200 engine...but my Vespa 200 tree that i have planted in the back yard isn't germinating 200 engines anymore...

I was going to ask for a sapling!

Update time - the good news is that I didn't run the motor, there appears to be a bit of shrapnel from the ring at the top of the crankcase.

Would love some more experienced opinions on what needs to be replaced (pics below) and if an oil change / flush would be enough to get any small shrapnel / dust out.

Appreciate the continued guideance!


A little of the shrapnel at the ring. Does the spacing on the rings look very loose or is this normal?

Biggest shrapnel piece I found, the rest was mostly dust

Scratches (?) in the case and it looks a little messy. Worrisome?

Piston looks pretty rough is this a sign of too much heat?

Bottom view of the piston - expected discoloration?

fly side seal is apparently toasted? Does this happen?

Building the order list and leaned on previous thread wisdom to pick the seals (vitron).

Questions for the crowd:
1) Any preferences for piston? It looks like both Meteor & Grand Sport have 66.9 (2nd oversize) pistons available readily - not sure if I appreciate the price difference on the GS.

Meteor - https://www.sip-scootershop.com/en/product/piston-meteor-2o-s_15629300
Grand Sport - https://www.sip-scootershop.com/en/product/piston-grand-sport-200-cc-2o-s_12092000

2)Stator - need to get a backup in case mine is toast / rewiring doesn't fix it. The stock ones seem to have lower power & are more expensive. BGM pro looks ok but mixed reviews. A few people point to the newer Cosa stator, but those seem fairly expensive. Love any / all opinions here - seems like a bunch of slightly bad tradeoffs all around.


3)Anything else that you'd add to the list below? So far I've got 2 CDI units and 4 plugs, 2 wire sets, 2 regulators so I can swap if need be.

Shopping Cart to get this beast running:
* Vitron seal (BGM, Malossi, Corteco Brown) for fly side in 24x35x7mm
* Piston w/ rings - meteor or GS
* Cylinder gaskets in several thicknesses
* backup stator - BGM Pro for now?

Thanks!

Looks like it's been running with a major air leak.
Never buy a Meteor piston. They are awful. GS piston will give higher performance and for over twice as long.
Pressure test the crankcase after it's all buttoned up. If there's still an air leak all the new stuff will be ruined.

Thanks Jack - noted and on the list!

Does the air leak explain the piston coloration?

Yep. The scorching on the underside of the crown and the lack of any wash (carbon buildup) on the piston are huge red flags. It also looks like a decent amount of detonation on the piston crown. Usually there will be dimples and bits of spatter on the inside of the cylinder head, too.

Is there any sort of oval depression on the crown of the piston?

The fly side seal was either never installed properly or worked loose due to the cylinder being installed off-square (I had this happen once when a *tiny* bit of weld spatter got onto the face and I didn't dress it down--lesson learned).

Ok, update time - ordered a new seal, stator & went with a pinasco 215 cylinder kit (always be upgrading).

Good news - it arrived in record time! In the meantime I was able to rewire the stator but unfortunately get the same values so it might be fully toast.

Now for the part. As CM mentioned: The fly seal was toasted but I left it in place until I got the new one in. The bad news is it looks like the bearing disintegrated (?) and I will need to pull apart the case. Sigh


Shipment time!

Sadness time :(

The fly side bearing is completely toasted and missing needles.

For future reference / searchability, there has been a lot of discussion about which oil seals are the best. As a minor contribution here is the side-by-side of the Malossi & Corteco Vitron seals compared to the original.

The two improved seals are very similar but the Malossi seal has a different design of the outer ring. (shrug)


Corteco vs OEM vs Malossi

Corteco close-up

Malossi seal close-up

Wrong choice on the Pinasco with the cheese piston. Malossi Sport MKII is the better choice. Then it's Quattrini if you want to go bigger…

The pinasco kit is not good. Bet they won't take it back

Yeah...shoulda' asked the Hive Mind here before pulling the trigger on that one...

I cringed pretty hard when you said you bought a Pinasco...

Points very well taken and return process started on un-opened box!

Lesson learned about rushing an order and why certain parts may be perpetually "in stock".

Currently leaning towards the Malossi Sport MK II 210 (1188870). Any thoughts / guidance here?

On the positive side, I pulled everything apart today and it does look like a very clean / nice build overall. The fly side bearing however, ripped itself to shreds. The area looks a little beat-up, is this something I can just polish / hone back to smooth or is it a bigger issue?

The bushing on the crank shows wear, but appears to be smooth. Should this be replaced?

Also, assuming a total noob loosened the main bearing retaining clips. Does anyone know what the torque value should be to retighten? I found just about every value except for that one

The case came apart very easily and so far my replacement list is just the fly side bearing, oil seal and new gasket to reseal. I will also put new clutch plates & a new o-ring for the cover. Is there anything else that is a must-replace?

Continued thanks and appreciation!


Flyside bearing remains

Another view of the crank surrounds - you can see a slight gouge in the upper right corner of the photo. Cleanable?

Crank appears to be smoothed and fits nicely. Should the bushing be replaced?

Anyone know the torque for these two retaining nuts?

The fly side bearing race is toast. The new bearing will come with a new race, so be sure to use it.

If you don't already have a bearing splitter, it's worth the $60 to get a cheap set at Harbor Freight/Northern Tool/etc. Removing that race without it is absolute misery.

The Malossi Sport Mk II is definitely the correct choice of cylinder this time around. If you wanted to go crazy, reed, etc., then you'd want a Quattrini M244, but that's a whole 'nother conversation

You're going to want to get some sharp grinder bits for your Dremel to do the port matching, but that's only scary when you're new to it. Ideally, you'll expand your intake timings a bit while you're at it. At the very least, clean up the intake and widen it a little bit.

Of course, either of those mean you're going to need to either do a full teardown of the cases and/or tape the crap out of everything to keep swarf contained. Given that it'll be aluminum vs. steel if swarf gets in anywhere, a little bit isn't going to hurt you, but less is still better in this case.

And for potentially-missing parts...
- Check the gear stack clearance and order a new shim if it's not within tolerances
- a new cruciform if you haven't already ordered it
- Take a look at the motor mounts. If they're ovaled or just really hard, replace those. Makes a huge difference in both general comfort and handling
- Replace the kickstart o-ring so your bike won't try to mark its territory with a drop of oil every time you park it.

Holy carnage batman! That is the race??

Have any thoughts as to why an otherwise newly-built & clean looking motor would toast that bearing so completely? Should I be deep investigating any potential root causes? Perfect! I'm looking forward to getting the right starting pieces and finally wrapping my head around the timing / flow of these engines for better performance Thanks CM - this is awesome! I was thinking about the gear stack last night - will deep dive to get the ratios and make sure they are sitting correctly

-------------------------
For future me:
-------------------------
Good gear tolerance starting place
http://www.scooterhelp.com/manuals/VNX1T.VSX1T.service.manual/50.jpg

Potential Issues with gear shims post
https://modernvespa.com/forum/post1659950

Someone installed the seal too deep.

To elaborate a bit more on what you said Ray...


Plantguy, if you install the oil seal too deep, it will block off the already too small oil channel hole that is there to lubricant the flyside bearing.


inside look of where the oil channel is

you can kinda see how crud has kinda blocked off the oil channel

and this is a look of the hole after i used a dental pick to clean out the passageway.

Thanks guys!

Whodat, amazing detail - very, very helpful! I will investigate and make sure that passage stays clear.

Crazy that such a small detail will cause such chaos!

Actually - unrelated question for you. Would you play with the stock gearing for P200 on 8in? Doing the gear calcs, it looks like 55mph at 6k rpm which is probably perfect for a backroad cruiser.

And you also have to be very careful if you decide to use any RTV on the perimeter of that oil seal during the install. It would be very easy to accidentally plug the oil channel with sealant.


As for for regearing a 200cc for use with 8" wheels...definitely yes you will want to...no i don't remember offhand what the optimal gearing is. It may seem alright on paper to cruise at 55mph @ 6K RPM, but in real life it would suck big time (unless your engine could spin up to 12k rpm). You would have VERY slow acceleration in 1st and 2nd gear (because they would be too short for the scooter to gain momentum). It would be like driving a tractor on the street. If you've ever driven a tractor on the street, then you would understand. I may or may not be planning on installing another P series engine (2005 PX150) in another VB1 this coming summer. If i do, i'll keep it on 8" wheels, and change the transmission gearing to make it optimal.

I always cut a slot on the seal so as not to block the oil hole...