Modern Vespa

Long time reader, first time poster.

I recently replaced a seized top end on my 1981 P200E. It has 36,000 miles on her odometer.

I was already on the fourth oversize piston (and re-bores), so I opted to get a BGM replacement cylinder kit:

https://scootersoriginali.com/products/vespa-cylinder-kit-200cc-rally-200-p-px200-bgm-original

I also got a new BGM exhaust stub:

https://www.bgm-tuning.com/en/product-category/motor/auspuff/auslasstutzen/

I went ahead and cleaned up and re-used my stock cylinder head

After assembling the piston, rings, wrist pin bearing and wrist pin, circlips, carefully mounting the new cylinder and tightening down the re-used clyinder head, then mounting my BGM BigBox Touring muffler, my black cylinder shroud is all out of alignment.

There are 3 touch points there:
-The 8mm bolt into the top of the shroud near the spark plug
-The lower bolt that also goes through the fan cover
-The sheet metal screw at the top that also goes through the fan cover

I can only attach 1 of the bolts/screws and the others won't line up. Take off one, and try another, now the other two won't line up. The sheet metal screw is the worst; it's lined up horizontally but off by a half inch. Maddening.

Some other information:
When I removed the BGM Touring muffler at the start of this project, there was an extra "tab" on the lower screw that goes through the cylinder shroud and fan cover. This is to mount a spring from the tab to the brackets on the muffler. There was only 1 spring, and it was stretched pretty good.

When I re-installed the BGM Muffler (using the BGM exhaust stub), there is no way the spring can be used. The distance from the hole in the tab to the bracket on the muffler is too close.

I read a rumor that the cylinder shroud for a P200E is different from a PX200E, but can't confirm that.

If I look inside the cylinder shroud I've got, I can see is it made by RMS, and has PX next to their logo.

I have taken the scoot for a 5 mile, low RPM ride around the (25mph) neighborhood and everything sounds good.

I'm hesitant to take the scoot on a real road; there are significant gaps between the fan cover and the cylinder shroud. Seems important all the air from the fan gets pushed through to the cylinder shroud.

Anyone run into this issue before? I've been searching the Modern Vespa web site and doing google searches on and off for a couple of days and don't find a thread for this crazy problem.

Any help greatly appreciated.

Well that kit does say up to 1980

Measure and compare

Shrouds are the same for both 200s. Is there a chance you installed a nut under the distance nut that goes on top right stud??

SaFiS:

Yes, I seated a flat washer, spring washer and 8mm x 1.25 nuts on each stud. Tightened in a star pattern. Then installed spacer bolt on top right stud. Not sure if that spacer is making contact with the nut. I will check.

Winner! Just the one

I have removed the cylinder shroud. Can confirm the spacer is seated on the nut.

However, according to the diagram, I should probably remove the spring washer from between the cylinder head nut and the spacer.

I'd put the bottom screw in (the one the exhaust spring hooks to) and then drill some holes that match where the two others go. That way the plastic isn't stretched and if you need to, buy some generic rubber grommets from the hardware store to fill the old holes.

MJRally:
I mentioned above there is not enough space to fix the tab on the lower bolt and the spring.

Could I have installed the muffler too well?

Doubt it, I think the plastic shroud is the culprit.

That said, don't use the exhaust spring and only use the bottom screw as designed. Drill a hole for the sheet metal screw so it aligns. The spark plug cap will hold the top part.

If you can't even manage that, time to spend some money and get a Piaggio one.

MJRally:

I was able to get the sheet metal screw to seat without drilling, as well as the lower screw fitted, no spring to the muffler. That sealed the gap between the fan cover and cylinder shroud so I've got good air transfer.

I cut a (goodly) portion of the cylinder shroud around the spark plug hole. This allowed the shroud to fit better, and actually accept the plug socket for tightening, and then the spark plug cap itself. I will take your advice that the spark plug cap will hold the top in place.

As far as the spring on the muffler, I tightened the lower muffler bolt really well, and will be checking on it after every 50 miles or so. The 8mm nut at the top of the exhaust is also tight; no visible blow by after about 20 miles in the neighborhood.

Thanks again.