Modern Vespa

That could be it as well. A new needle bearing did not come with the kit. I should have ordered one but the old one felt pretty tight since it had only had a few hundred miles on it. They should supply a new bearing with the kit since they supply a new wrist pin and the clips and those are not much of a wear item.

this would've been pertinent information at the start of this quest. you did https://www.bansheehq.com/forums/topic/174387-how-to-measure-squish-correctly/

hopefully you didn't destroy the big end of the crank. you'll for sure need a new little end bearing. oh, and new circlips. I recommend never reusing them.

measure the squish and see if you can get away with making a thick gasket, or if you'll need to make a shim gasket out of some type of alloy. or if you'll need to order a new kit.

Bearings come with crankshafts not a cylinder kit. But it is better to use the correct bearing.

totally agree

One more test idea. Hold the flywheel stationary and push down on the piston. There should be no downward movement. If there is, small end bearing/wrist pin need replacing.

Here's a thought, what cylinder head are you using on the new kit? One that came with the kit, or the original head? That ring mark on the piston is too far in, should be closer to the piston edge with the correct head and no clearence.

ohh. keen thinking jack.

mercato lists for a 150 cyl w/o a head. so using a 125 head on it could potentially cause issue. notably mercto says in their copy that a different head is needed to run that on the 125's, which they sell separately (it's a generic 150/P head).

so, I see I variety of possibilities here:
>OP bought the head and the milling is cause for contact.
>OP didn't buy the head and is using the old head, that while it might be 150 is still incorrect (possibly non-dome style) and the milling is exacerbating the situation further
>OP got the wrong parts-- piston or head

Time for the results and the solution.
Removed clutch cover, plenty of clearance, no rubbing. Feels great.
Kick start gear seems OK, have been running with it for months.
As for squish, piston area is smaller than combustion area so the solder did not even touch. Odd to me but moving forward. So that is off the table. No idea where the circle on the piston came from shown in previous pics.
Zero slop pushing on the piston. I now learned to change the bearing when servicing the piston and/or any associated parts.
I am using the original head for a 150. There is a part number cast in the head that told me it was correct in the past so I just opted for new cylinder and piston. I ran with this set up in the past but had a leak issue with the ports mating area. I copied and pasted the cylinder kit part number from the last order.
So, when installing the flywheel with this problem child cylinder, the clearance for the flywheel fan near a side port was very small. I saw a small gap so to me it was good.
I gouged out the cylinder to increase the gap but was concerned I might penetrate the port so I stopped.
I took the fan to work and chucked it up in the lathe. It was a bit wobbly. I squared it up as much as I could and shaved a bit off.
Installed everything and the sound has disappeared. I know the rule of only doing one thing at a time but I was frustrated.
My guess is the gap between the fan and side port was enough but perhaps the centrifugal force made the fan stretch and rub. The ZZZZZZzzzzzzzZZZZ that greasy was referring to was the fan wobble fading in and out.
I also wanted to apologize to Greasy for not divulging the "Pertinent Information" earlier.
I have ordered a new cylinder kit and will replace it in the future. I still need a better seal and I have a slight leak still and that gouged area bothers me. I tried to avoid scaring the cases as much as possible.
So in my defense, I am 65 years old and still work a very demanding engineering job in the Silicon Valley. I am pretty much brain dead in the evening when I work on this thing so I am spinning at times. As we know, Engineers are not the best communicators. Thanks again to all who contributed to my issue.

😑

if you had said that bit about the cylinder and the fan at the jump, one of us would've caught that. I know several of the collective here have had that problem.

likely what you milled the cylinder down by was the clearance you needed.

5 lashes with a well used clutch cable for omitting information.

glad you got it sorted though.

In my defense your Honor.... I did not think of the Flywheel gap until the next morning after I exhausted the other options the night before. I gouged it out after work, put it together, noise gone. Posted the results.
As for the "Lashes"
May I have another PLEASE !!!
Thanks again for all the input.