Modern Vespa

I'm at wits end with this Malossi 210 kit.
I'm on my 3rd clutch seal. Each seal, I get about 50-100 miles of perfect ring. Then it slowly degrades. Eventually start pulling in oil through the seal at the crank. This is a '79, grooved case. I've run black and blue seals. New Crank, New bearings, clearance measurements. Squish, timing, jetting, all check out. Factory install tool, perfectly seated. I have never quacked a clutch seal install in dozens of builds. Much less three in a row.

Need some pictures. As you are describing it is very unusual.

This was the last time it was open. No visible damage. Oil obviously getting in around crank. This time I installed a blue Corteco seal. Haven't pulled it apart yet but, ran beautifully, then started acting lean on the last leg home. Now smoky idle, can't pull off from 1st gear. Leaned idle down but, will "flood" and die.

Soinds like ethanol damage

You should look to ethanol resistant seals

Agreed. Neither the black or blue are ethanol resistant. Use a BROWN Viton/FKM seal.

I use only ethanol free fuel. So, there's that.

Either way. The brown seals are far superior

Any link. USA on shore? Gotta replace anyway. Might as well take a shot on the brown.

Did the kit come with seals?
https://www.scootermercato.com/Scooter-Parts/Malossi-Seals-and-Bearings/M-6618069

https://www.vespajets.com/product/bgm-vespa-clutch-side-oil-seal-e10-brown-viton-lml-px-pe-rally-ts-gtr-sprint-v

This seal is the one you need, where in the US i don't know.

Got a picture of the crank seal surface? Tested the crank for straighteness?

This.

I've had cranks twist out of true and kill seals multiple times. Also, check if the big end pin has pulled out of the web at all.

It's always been the fly side in my case, but that could just be bad luck.

Once it happens, you need to get the crank back to true, then weld the big end pins or it'll just keep happening.

Thought so as well. 3rd seal. New Crank. New bearings. Also, I've owned same bike 20 years and did stock overhauls 3 times previous without issue. That's why the cursed logic is at play.

www.scootermercato.com.

Product: M 6618069 Malossi Viton Oil Seal Set P Series ScooterMercato.com.
Price: $36.40

Link: https://www.scootermercato.com/Scooter-Parts/Oil-Seals/M-6618069

The BGM seal jack posted is also good. I use both the Malossi and/or the BGM.

Its actually difficult to find these in the states for some reason. Why doesn't the market carry more of these type of premium seals, and other premium parts I dont understand. I am very particular in parts choices, and all things; so find myself having to go directly to the overseas vendors for many things.

New crank could have been crooked to begin with though.

Kind of a sadistic coincidence but possible. Frankly tired of pulling this thing apart. Also, worried if the crank isn't crooked, pulling it in and out won't help it. But, I guess I gotta give it another shot.

You could try checking it in place. I have no idea if it would work. You have to pull it to replace the seal in any case.

And, yeah, I know the feeling of endless frustration when it comes to splitting cases sometimes.

Only thing to wonder before I pull the trigger on these, they seem (from the picture anyway) to have a metal edge rather than rubber. Is that an issue with the grooved seal edge on the earlier P-bikes?

Yep, I'm hoping the issue is more stress, heat, and increased crankcase pressure blowing stock seals. But, you are correct that I can't get to the seal without pulling the crank. So, I'll have to check it out and cross my fingers. Already dropped some Benjamins on a new crank. Hate to have to visit tariffville again.

Actually yes You do need the rubber edge seal. Jack posted a link above to the correct BGM seal, but likely You'd have to order directly from Scooter-Center. Check with www.Scooter-Speed.com in California, they may have it

*I have used metal edge seals in grooved cases without issue, but cant vouch for or take responsibility for success or failure if You choose to do so.

Is this done with a runout gauge?

No you don't. Granted, the groove on groove setup works fine on low compression (e.g. factory) engines, but it can be challenged on high compression kitted engines.

I use metal edged viton seals with loctite (and have been for 20 years), and despite hearing that that's not how it's done for ages, the metal on metal with glue method has never failed me, nor those around me who do the same.

Blue or black (nbr) seals suck ass generally, but they likely wouldn't fail that fast, that consistently, without another issue accelerating their failure. I agree the crank seems like a prime suspect.

Seem to me if the crank was so run out that it destroyed a clutch seal in 50 miles, you would've noticed a massive amount of vibration right out of the chocks.

The clutch is another angle. Being that is the only unchanged item from build #1

Well yes; like I said - I use the metal seals regardless of the groove or no groove; but thats not the 'proper' way to do it.

Regardless, those black seals are trash and I only recommend the brown viton seals. To elaborate further on my personal choices, I only use the Malossi metal edge seals for the clutch side; as the link I posted above. Add some Loctite 603, and its a job well done. That said, the edge for the seal has to be super clean, not scored or chipped, or buggered in any way. If the lip is not great, no seal will work well.

All that said, as many have pointed out; I would look closely at your crank being the culprit for wrecking multiple seals in such a short time.

Balance Factor/Crankshaft Balancing
When a crank is really bad, it's possible to see the flywheel wobble.

This calls into question the flywheel as well. I am using a stock 5.5lb flywheel. I won't get around to pulling it apart until this weekend but, I will look at the entire rotating mass. After the second failure, I suspected a bearing issue. Found the fly side to be a little heat burnished. New bearings and crank followed. Now just mapping out my rabbit holes.

May be possible that:

A) Bad/Poor quality crank out of the box (Mazzi race cut from SIP). Add Higher RPMs, torque, etc... Progressive degradation and seal damage as a result.

B) External vibration from clutch and or flywheel at high RPMs deflecting through crank damaging seal. Potentially damaging crank

C) Poor quality, stock type seals and materials unable to handle the higher heat, crankcase pressure, torque.-Best case scenario.

D) Blowing up mailboxes and toilet papering neighbors houses as a kid has finally unleashed a karmic punishment that requires repeating the same assembly/disassembly process.

Some other notes:
Compression tested around 155PSI
Breather removed, cleaned and confirmed free each time I got into the engine
Timing dead nuts 18°. Mechanically verified TDC and 18ºBTDC marks with dial indicator to piston and degree wheel before setting with timing light.

Nothing of note. In fact, ran quite smoothly. My Pinasco 177 kitted GT vibrates more at speed.

Haven't gotten back into this yet. Decided that before I tear this engine apart again, digging the garage out from under itself would be in my sanity's best interest.

No progress to report. Turns out step one of "rebuild the engine" is "find the floor."

I can't speak for everyone, but most of us have been there.

+1

I kinda live there

+2


Every time I open the door to my shop I get anxiety.

+3

I have to roll out one of my scooters before I can slide into the garage

I broke out the Home Depot card. Now I have an over-budget cleanup fueled by Cafe Bustelo and 0% interest for 6 months.

+ 7. My shop is typically super clean (ocd), and I still have (personal) problems getting to the fun projects....

Well done on the Cafe Bustelo. Bonus points if made in a moka pot

Brown Viton is the way to go. Get a Viton flyside while you're at it.

Double-lipped, the kind that's 1mm thicker than original (fits fine).

Seal in hand. Motivation in toilet... LOL

Taking a trip to SoCal for Mom's 80th this week. Will be back at it soon.

Curious if the Mazzi cranks are just flexing under pressure. Consistent with first 3 rebuild symptoms.

1st: Ran about 50 miles, was able to tune it in. Performance flagged off and started sucking oil.

2nd: same crank, new seal. Ran for about 1 to 2 warm up runs, sucked oil. No visible seal damage.

3rd: New Mazzi crank. New seal. Ran beautifully for several.around town. Did a 60 mile ride, started coughing up about 5 miles from home. Limped it. Tried to start next day, blowing oil.

Yet to get into the seal for inspection.

Have the brown Malossi seal.

May just bite down on one of these regardless of the condition of the seal.

https://www.racingplanetusa.com/crankshaft-touring-rotary-valve-57mm-stroke-vespa-px200-p-222960-1.html


That and a BGM lightened flywheel.

Did you check if your crank was true? Is the pin not fully in place?

I've been burned by Mazzi cranks a few time, but if you get them trued up, then weld the pin, they'll hold together.

Also, is there a reason you don't go to the 60mm crank?

You're almost certainly leaving loads of power on the ground because you probably still have absurd squish and random port timings.