Modern Vespa

As part of my engine rebuild, I replaced the mounting bushes. After just a few minutes riding (still setting up the carb) I noticed that the inner metal part of the bush has started to work its way out of the rubber. It seems that the shock mounting is wider than the engine mount. Is this normal or should I try and space the gap with washers?

It is normal shock mount wide. I noticed that this metal tube always tend to slide onto side and decentering.
You can try to press metal tube to center it. But I also noticed that if it starts to slide once it will slide again and again.

This is SIP bush, I thought that it can help with tube sliding into it and mounted it on my P and PK.


But just now checked on my PK and... it was hold only for 700 km after new SIP bush was mounted. Maybe someone knows better what can causing tube sliding? I can guess only main engine bushes but on my PK it is new and have no any damages or worn.

Mine is this version from BGM:
https://www.scooter-center.com/en/silent-block-set-shock-absorber/engine-bgm-pro-made-in-germany-oe-10mm-x-48mm-vespa-px-1984-t5-125cc-pk-bgm7956

I'll see if I can push it back in and add a couple of washers as spacers to stop it moving again.

Did you by chance use grease/oil/spray lubricant to mount the tube in the rubber bushing?

No, it came as a single piece, ready-assembled.

I would go another direction then. Use the SIP bushing with a 9mm tube. My .02 cents.

I use 20mm socket to hold bush on place and long bolt to push metal tube.

Had a good look at it today. In fact, I don't think it's a problem. The inner metal tube is as long as it can be between the sides of the shock, so it's going nowhere. There's not even space for a single washer. The rubber bush is the same width as the engine mount so as long as it stays there all is good.

And after only 210 km tube was slide again. Don't know what to do to prevent it. Will try to change rubber bush.

For a shock on one of my P's, i created a spacer washer out of 1/8" thick HDPE plastic (cutting board). The i.d. of the washer slips over the spacer tube, and the o.d. is about the same diameter at the shock mount on the engine case. I installed one on each side of the shock bracket.

I am guessing that there is some 'lean' to the motor due to normal silent block wear and the pin is not square to the shock so it walks to one side. Operation-wise, it shouldn't make any difference at all other than metal-to-metal contact between the shock bracket and the lug. Stick a washer in there.