Modern Vespa

fly side seal rubbing? Baby chick caught in the stator? Can you feel any rubbing or resistance if you turn the flywheel by hand?

Are you sure that is a leak?
Sounds a little like rubber.
Oscillates withe the motor resistance.
Feel like I wanna take the fly wheel off and see if it goes away.

It's definitely 360 degrees of squeak.
Does it squeak if you turn the flywheel by hand?

No squeak when turning by hand.

Just rolls through all 360* as normal.

Spark plug is tight. Cylinder nuts torqued to spec.

Last edited by Birdsnest on Wed, 15 Mar 2023 02:07:15 +0000; edited 1 time

kick start o-ring?

(can you tell I'm grasping here?)

I'm willing to try anything at this point… even baby chicks in the airbox!

Pull spark plug wire or the like - so it cant start.
Use a drill to spin it up.
Squeak?

If no - something kick start related.

Seems to accentuate with each stroke of the piston.
Would suggest head leak if its a leak.

Or - the rubber on your kick start peddle is slipping.

Try a different pair of shoes

definitely seems to be kickstart-related.

Try kicking it with the clutch held in to keep the crank from turning. That'll help isolate it further.

Tried new shoes …and with the clutch lever pulled.
No squeaks…

https://youtube.com/shorts/Pohbg2MJU0k?feature=share

Last edited by Birdsnest on Wed, 15 Mar 2023 02:33:41 +0000; edited 1 time

Seems like we're back to something crank-related, like a squeaky fly side seal or maybe a stator wire rubbing.

Try pulling the flywheel and test again?

Ok.
So I would pull the spark plug and try again.
You are gonna wanna use what ever shoes you want...

Don't pull clutch this time.
Should isolate head leak if thats it.

fly seal or head leak - is where my current money is.

Thanks all…hoping stator wire… that might be it!
Will update on the 'morrow…

First thoughts are cylinder. Most likely the head. Crankcase pressure test would find it.
If it doesn't stall when over 4 turns out on the mix screw. It's enough to do damage over a long time.
On the other hand, could have a squeak toy jammed on the exhaust.

I was assuming that the motor was pressure tested successfully. If not, then disappointment should have been expected.

coming in hot with some strong "I'm not mad, I'm disappointed" dad vibes!

I had a few theories that we shared on the slack employee chat last night, but no ham wagers were laid.

^^^^
/giggles

Updates this evening...stay tuned.

There's no need to punish people who install motors without pressure testing them. The motor will do that for us.

^^^
chuckles

Crazy day yesterday. Got home super late after an 11 hour work day.
Put on TX garage clothes (Read - banana hammock, steal toes, work gloves...sorry for the mental picture...) and pulled the plug:
kicked it over:
Still squeeky.

Mamma bear then came out and reminded me, unhappily... that we needed to leave to meet friends for grub. I asked if I needed to change? Lead balloon. :-/

Back into civilian clothes and no more garage time for the evening.

Flywheel removal this evening.

The hunt continues...

.
~

Sorry sorry… there was some poetic license there to draw the ire of G-man. Just shorts and boots and a sleavless t-shirt. (That's probably enough to draw his ire anyway.)

Leak is isolated *I believe* to the Airbox/carb zipcode. More soonish.

🔜 .

Disturbing mental images aside, I'm pleased you've apparently located this annoying 'whistling' problem essentially externally.

Based on how he was dressed, I'm guessing the bike was trying to wolf whistle at him and just having limited success.

Well, he is working on "The Spanish" and it's had lots of salty nuts cross it's seat.

The gold sequined g-string only comes out for special occasions!

Like engine start ups!

You know the rules about shop attire… house pants are minimum. Closed toe shoes at the very least.

No stem ware.

Don't wanna live in that world.

Last edited by Birdsnest on Fri, 17 Mar 2023 14:01:27 +0000; edited 1 time

Frankly you, Sir, have read my basest thoughts that were until now successfully repressed. Thanks a LOT!

Last edited by V oodoo on Fri, 17 Mar 2023 09:05:22 +0000; edited 1 time

And you, Sir, are not helping!

I'm no philistine, I'm just clumsy and I don't like broken glass on the floor. and I don't like doing dishes-- especially the wine glasses!

I like drinking wine out of thick-rimmed, dishwasher safe wine glasses even less than either of those.

Still searching.

Squeeks McGhee is hiding in the carb/airbox area.

Checked gaskets, swapped carbs.. I thought for sure it was sorted when I found the airbox/case gasket appeared to be poorly cut from the factory. I recut to make sure it wasn't covering the inlet, put everything back together, and it sounded good for 5 or 6 kicks.

Then I rode it around, and gave it a few more kicks and my friend Squeeks was back.

Pulled off the flywheel and looked around... didn't see anything.

Gonna try a different airbox... but fear we may be in for another engine drop.
*kicks dirt*

Ella tiene una fuga.

Probably clutch seal... but damn it if didnt run pretty well.:-/

Need to maybe do a smoke test and find out where the leak is for sure.
Anybody have a link to the old smoke test thread?

Also... in other crazy news the rear shock spacer delaminated from the metal plate and the whole back end dropped down as I was removing the rear wheel.

Glad that happened on the stand and not under load while rolling. Eek.

The shock buffer….

Always nice when problems happen in the garage and not 30 miles from home!

here's a link to CM's lube based smoke show:

https://modernvespa.com/forum/post2572209#2572209

It sounds so much more interesting when you put it that way...

gotta punch it up for the google SEO and keep it interesting!

*murmura ininteligible*

I did not make a smoke machine or fashion a vespa engine bong.
I just opened it back up.

Frustratingly... I can't seem to locate any crazyness or obvious area that would be leaking!?! Should have made the bong I guess.

I did find a weird scratch on the lower part of the flyside cylinder pad. Almost like a piece of metal got dragged by the crank. Crank looks good though?
There is some signage of swarf here and there. More than one would want to see.. but I cant figure out the source. All the gears look good. Seals look good.

I'll replace the seals again since we are here, but at a loss still...

*se rasca la cabeza*


Hmmmmm

Agree... Can't see much trouble there from this pic. I only have questions so far.

How does the crank look, and also the other case half crank recess and rotary? Scoring anywhere? Any clues about where the swarf originated from? All carb screws accounted for? Piston, rings and cylinder head in the same condition as they were before you closed the cases? Seals look good? Did you float the crank after the motor rebuild and the cases were buttoned up?

What a relief that you and the scoot are none the worse for wear after the upper rear shock rubber gave out.

Looks like maybe the crank wasn't seated true in the bearing or the bearing may have been slightly tilted in the race.