Modern Vespa

I'm building up my first p200 motor from NOS piaggio cases and all new internals. I had the engine built and buttoned up (but never run), but had to split the cases again to deal with a kickstart issue.

I've got a Malossi 210 top end, but I hadn't planned on matching the cases. Now that the cases are split again, I wonder if I should go ahead and grind away some of the material on the port on the flywheel side case. I can grind that out and protect the bearing from getting fouled.

I'm not interested in disassembling the crank side and don't want to try to match that case (too hard to keep swarf out of the bearings).

So I guess I'm wondering whether it would be desirable to match the one case but not touch the other, or if it's better to just leave the cases stock given that I'm not going to be matching the other.

[Not sure why the pic isn't showing...if you right-click on it you can download it, it just shows the case and how the port doesn't match well with the malossi cylinder; the black Sharpie was drawn using the cylinder, not the gasket]

Hmmm ?

Couldn't open it.

Maybe rename it and save it again on your end, and then upload in a reply.

No idea if matching one side will cause problems on the other side. Worth a try!

If not, the bolt on 210 is still better than stock so moving on isn't a bad idea either.

If you match only one side, all the horsepower will only go to that side of the engine. Then the scooter will never steer straight. You'll only be able to ride it in circles.

Renamed attachment...

This is helpful to know. I was wondering.

(And I don't want to drive in circles!).

Test for image

In all seriousness Yackee, it won't take you very much time to strip down the cases a little bit further to do the porting on both halves...about 3 minutes to remove the clutch, and another minute to remove the crank (if the cases are still currently apart). You'd be missing out on a LOT of free HP by not matching the cases up with the cylinder. You don't have to go "whole hog", but even some matching would go a long way. It will also get more air and fuel effciently down to the piston. And more fuel around the piston should keep it more lubricated and cool.

Which Malossi 210 kit?

The 'new' one with the o-ring:

https://www.scooterwest.com/p200e-malossi-210-kit-w-head-m3113764.html

Ok. This is a Malossi Sport. Matching the cases on both sides equally is no bad thing but not any priority. If using a stock crank and stock inlet port, I really wouldn't bother.
Most important is no air leaks when the cases go back together.
Timing at 18 degrees exactly and carefully checked. Major upjet involving an AC120 , will prevent it from self destructing.

Finish splitting it and port both sides, you have some huge transfer ports there getting nothing. I've seen a few videos online where people roughed in a port with the case assembled. I've done it a time or two myself. Taped everything off, put the sholp vacuum next to the port, sucking up shavings and cleaned up the best I could with my shop vacuum. Use some plastic and copious amount of duct tape to seal things off.

The cylinder transfers are designed to direct the gas flow up and into the combustion area above the exhaust port. If you did one side and not the other, then in theory anyway, you could have a situation where the fresh charge is more towards the not-ported side... this could in theory lead to uneven stresses across the piston and pin.
If your jetting was not quite right then stuff might happen, depending on your state of tune. It might not either.

I suggest either do both sides or neither.

hi yackee
leave it as it is is the simple approach, its not worth it
https://www.youtube.com/watch?v=G8V5Dan_d2k

pnp, with a lot of edges also works fine
a malossi sport 210 ie hits 17hp at the wheel
with just pnp with sip road
on a rally 200 case, nothing ported, this here
teninch dyno

https://cdn.germanscooterforum.de/monthly_2019_11/1743417038_rosirally-ddogmalossisport211plugandplay.thumb.jpg.11440c4a18c8cfd44b3248c683c8ce6f.jpg





of course at 2 stroke engines, every optimizing is a good step in the right direction, the small ones are hard to verify, but the sum of quite some small things, is indeed feelable

you can also edit both sides, even when the engine stays in
its easy possible, such as:
https://www.youtube.com/watch?v=H-VX3jYSmVg



the polishing group will now shout loudly, thats ok and respected
doesnt chaange that: its easy possible and works fine

asymmetric flow causes more mixing of the fresh charge with the exhaust gases and can also allow more fresh charge escaping out the exhaust port.

The way the 200 cylinder is twisted off center already makes this a bit of an issue, so I'd try to maintain as much symmetry as possible.

Matching the cases tends not to impact max power by much, but can increase power below and above the max.

Here's a pic of what the 210 Sport base gasket looks like laid over the top of the engine cases. Nevermind about that 3rd port on the case that had already been open up. That happened in the past for a 215 cylinder kit that used to be on it. A significant amount of flow will be blocked if the cases aren't flowed to match. But it sounds like the consensus is that won't add much HP or torque. I'd figure I would post up a pic so there's at least something interesting to look at.