Modern Vespa

Is the clutch cover oil way still at least partially intact?

the main vertical channel Yes, the upper part is basically gone.

The cases are early 77/78 P200, with cast in oil slinger; not the separate plastic slinger.

I would say that the clutch plates did seem a bit dry, upon inspection.

Perhaps I will try a different clutch cover, with an intact channel; if it fits with this basket.

I'm still curious exactly how these clutch issues would lead to the crank bearing play, but it is all connected…

Sorry about your engine troubles. That's a strange one. Similar experience with my 200 doing a careful build, but things still went wrong.

I find that on the early P cases the clutch side bearing is harder to align. The LML/PX cases have a nice big shoulder to seat against. You know when it's home. The metal tab holders on the early P cases seem less precise. I don't know if that is your problem, but I had to do a little tapping to align the bearing.

I'll keep that in mind. When I installed the big bearing, I heated the cases & froze the bearing; it dropped right in to place without any resistance. Gave a little tap to be sure it was home.

I'll be pulling and splitting the cases later today.

Highly recommend the breather mod I posted in the "random tricks..." thread, page 17. My three P125 cover channels are all (too) dremeled.

Good tip! I have considered doing a similar mod for quite some time, using a breather on a tube rather than directly on the clutch cover. Might be time to finally do this! Thanks for the inspiration

I'm waiting on arrival of new crank bearings and a case splitter/crank pusher. I'm shocked and didn't realize I didn't have this tool already! I guess I've always made due without it. The crank is still new, so I dont want to risk using a mallet.

Qascooter was kind enough to lend me his crank truing stand, and wheel balancer. I'll check the crank for true before reinstall. I used the wheel balancer to check the flywheel, which is well balanced.

I suspect there are 2 things that contributed to the breakdown.

1. lack of oil to the clutch & clutch cover/plunger. The oil stop rib on the case has been mostly ground away by a previous builder. I'm considering having this welded back on… gotta check clearance for the clutch basket first. That or I'll over fill the gear oil, and extend the breather, as per Ray8's suggestion.

2. Oil sucker problem. It looks like there was a slight oil sucker happening in the usual spot. Closer look at the oil has a bery tiny amount of fuel in it, as well as burnt black oil in the cylinder. I'll be extra cautious on reassembly. although I am very methodical on assembly, these things happen.

The instructions for most aftermarket clutches say to snap off the tab on the case and grind out the cover. If these things were the cause then wouldn't it be happening to loads of motors?

I'm about to start building a motor in PX cases where this tab has been removed by a previous owner and the BGM clutch I'm using probably requires the cover to be modified, so I'm wondering how concerned I should be about this.

I'm definitely running more gearbox fluid with extended breathers in both my scoots. The Molle clutch I have specifies it their instructions too.

Your scoot was going so nice, bummer.

I had the gear oil get low in my Stella. Part of it was an oil sucker problem but also metal feet on the center stand changed the angle. Instructions for filling say to fill until it runs out the hole, but it will hold a lot more, so now I pump in a shitload. Haven't had it blow out the breather yet. There is an FMP video about this.

You make a good point. For my situation I feel like it was caused by a combination of factors. Parts failure and/or poor quality parts could also be a factor. Hard to say for sure. I'm also considering what I could have done wrong, or carelessly while building; although this isn't my first rodeo. I'm focused on rebuilding and alleviating possible future failure, to the best of my ability.

To recap, the two main failures were the clutch pushrod disintegrating, and flywheel side crank bearing developing excessive play. Whatever the cause, these will be replaced and fingers crossed all will the well.

I usually over fill a bit, but not excessively so. There is plenty of room for alot more, so I'm going for it.

I'm thinking of measuring out 350-400ml. Anyone have suggestions for exact 'over fill' capacity?

I don't think there is an over-fill capacity with the breather mod I mentioned.

400ml is enough here with CR80's, snapped tab & dremeled cover channel.
You can feel/hear the difference vs 220 or so till it dribbles out on the stand.

10 Molle spec is 500ml

Good to know!! Thank you!

Good info Ray8 - I'm filing that away for future reference!

Where would one find the instructions for the 10 Molle clutch? Mine didn't come with any, and I Googled it with no luck.

I'll dig them out when I get home today and take pics for you.

Thanks Rob👍

Case splitter/crank pusher, crank seals, and a stack of cylinder base gaskets have arrived! Always order extra lol

- Thanks to Scooter Mercato!

Also arrived, not shown; crank bearings clutch plungers and pressure plates. Again, with some dupes; because hoarding = planning ahead.

- Thanks to Scooter Speed!

Re Re Re Rebuild coming up soon!

I love getting new tools! Paying for them, not so much. 🤣

Looking forward to the repair/rebuild.

The case splitter is so bad ass, I love mine.

Yeah for sure! Most rebuilds I've always replaced the crank, for one reason or another; so it wasn't needed. I've been fortunate in not having trouble with the actual case splitting part. This will make delicate work more efficient and done properly!

I'm being extra cautious with my 'new' crank, so this is a welcome addition; and will be put to good use

I agree!! This one is not that bad, all considered. With this project, and those waiting to be done; it is a wise investment.

I put the new case splitter to work to remove the crank. Pushed right out easy peezy.

Then I went about checking the trueness of the crank, using Qascooter's crank truing stand & dial gauge. Thanks Scott! Both the flywheel side and clutch side bearing surfaces run true and straight, with just the ever-so-slightest move of the needle; I'd say - 1/1000'th. So the new Polini crank is still GTG!

Now its onward to hopefully figuring out why the extra play developed in the fly side bearing. I'm leaning toward a bad bearing from the get go, but hard to say for sure.

One thing to note that may have been a factor, that I forgot to mention previously; was that I used to 2 different fly side bearings to complete the installation. I had 2 new SIP Premium fly side bearings. When installing the flyside race on the crank, I accidentally overheated the ring by leaving it under the heat gun for too long; leading to heat discoloration and possibly changing the hardness. So I grabbed the ring from the second spare bearing, which was the same SIP Premium bearing. The outer was already in the case, otherwise I would have used the 2nd complete set.

Has anyone ever noticed a difference in the inner race outer diameter, when comparing the same bearing from the same manufacturer? I would think that the pieces are machined to spec as a lot, not fit for each individual bearing.

For the Re-Rebuild, Flywheel side bearing I have a new Nadella/Piaggio original spec. I actually have 2. Both inner race out diameter measurments are 28.95mm.

For the clutch side bearing, I have the preexisting SIP premium; which is already installed. This is a 9 ball, c4 bearing. I'd say its still good, with only a few hundred miles. If I want to replace it I have another of the same new SIP premium, or a NA/Piaggio 8ball C3 bearing. I'm not certain I even need to bother changing, as best I can tell; the issue is with the flyside only.

I still have no solid evidence as to why the flyside bearing failed, but I'm moving forward.

Measure here and here:

DUH I feel stupid….

Measured again, at the proper positions. Flyside is +\- 0.002, clutch side is just a hair less than that.

So its not exactly perfectly true and straight

That's not too bad though. But yes, measure out there!

I did some more careful measuring, this time with my MM dial gauge.

Flyside: pin @ 180/6oclock: -0.05mm
Clutchside: pin @90/3oclock: -0.03mm
Clutchside: pin @180/6oclock: -0.04mm

If you want to take a crack (literally) at getting it closer to 0 and have a spare or two to practice on, check out this to see where and why it's off a bit*.
*A lot of cranks land at .002+, especially when shipped in a box meant to sit on a shelf ie not double boxed.

Thanks Ray8! I love 2 Stroke Stuffing! I've watched a ton of his videos, including this one. He clearly explains the process of measuring, the reasoning, and how to for truing.

This Polini crank arrived in a thick styrofoam box, fully supported all around, that was then double boxed. Not the thin cardboard of a Mazzy crank haha.

I may give this a whack! I have a few used stock cranks I could whack round a bit for practice. I've had cranks trued, just never done it myself. I always left it to the pros.

Or I may go with plan-B…. stay tuned lol

Do it! It's strangely satisfying. I enjoyed trying it.

Maybe a stooopid question, but…could ring blow be a contributing factor for crank bearing failure? The old "old style" Malossi kit I've been running has lots of miles, and some ring blow by. Its due for an upgrade, but I've been trying to go the budget friendly route; perhaps detrimentally so in terms if my wallet