Modern Vespa

Swiss - I had to take a closer look to really see the hole.
Now that I have - perhaps there is a simpler fix.
Looks like the exhaust port has a stub that is screwed in.
The hole is just behind the threads.
If your stub is - or can be modified to be - longer with no threads for a small portion - it can cover the hole.
Further - if it can go until it bottoms out to the edge I am showing below - it would seal that off?
How about just having a ring welded on the port stub so that you can bottom it out? Can you show a picture of the stub?

That might be more work than needed. Especially if they replace it. On top of that hole, the threads for the exhaust stub seem to be cast poorly as well. I have tried repeatedly to get the exhaust manifold threaded on and it just wont thread on. It's not the manifold that is the issue. It's brand new, and I double checked it was the right part for this cylinder. Ordered it from Mercato.

Here is pic of my new exhaust manifold.

Got it.
Well - now seeing - if you wanted to - you could take a Dremel to the first 2 or 3 threads - and then run it in until it bottoms out - covering the hole.

But of course - you would have to be able to run it in!
Sounds like the threads on the casting need to be chased.
Send that thing back!

🙂

Installed primary and finally figured out a problem I had when doing the same on my Stella. Original discussion here:
https://modernvespa.com/forum/post2371849#2371849

The SIP needle bearings I bought for the Stella didnt fit and were not as rounded on the ends as the LML original which led to the primary not rotating freely. For the Stella, I just ordered new bearings from mercato and they worked. I saved the SIP needle bearings that were new at the time and just installed them into this primary. Once torqued down it rotates freely with no issue. I was talking to greasy about it and he confirmed that there are slightly different needle bearings based on P vs EFL model primaries. Quirky little difference that you would never know and was barely noticeable as they measured exactly the same length and thickness... only difference being the P needle bearings are flat ended, whereas the LML/EFL needle bearings are rounded ended.

Replacement barrel on the way, along with some needed random parts to complete engine.

They did not want me to send old barrel back due to cost of shipping, so this defect barrel will be experimented on to see if I can get the hole fixed up, and also to see exactly how wide I can dremel the exhaust without breaking into the stud holes.

Jack, this means I will do the extreme of what you think is ideal for working a p200 stock barrel. I'll even open up some transfer ports in the skirt. No fear on the already defective barrel.

Just got an unexpected call from Dave @ Mercato. He heard I had problem with the p200 barrel and wanted to let me know that he had same/similar issues with the taiwan made p200 barrels and stopped carrying them. He confirmed everything that I was seeing wrong with my barrel, one being all this leftover artefacts from casting was not cleaned out of the ports.. so there is a lot of rubble/roughness in the ports that he said his tech had to knock all of that out using screwdriver and essentially a wire brush. Second problem which he said was why he stopped carrying the taiwan barrel was the exhaust thread issue I noticed as well. The threads that are cut aren't cut straight on, but slightly on an angle so when you try to thread the stub in, the stub can't get onto the threads because it hits up against the cylinder/fin wall. I asked if he was able to solve that problem, possibly by dremeling the fin wall on the side that contacts with the stub. He said he just threw those barrels out. Kinda shocking that SIP sells these barrels if they have so many issues.

If the replacement coming from SIP has similar issues and doesn't work then I'm ordering the part from Dave @ mercato because he confirms he sells the Piaggio original part.

I'm gonna see if I can dremel the barrel opening at the stub to get the stub threaded on, but even if that happens it might not allow the exhaust to mount properly since its gonna be on a slightly off kilter angle compared to stock.

Part I originally ordered was the SIP Serie Pro p200 barrel with GS Piston:
https://www.sip-scootershop.com/en/product/cylinder-serie-pro-200-cc_41470700

They sell the Piaggio original which instead has the ASSO piston:
https://www.sip-scootershop.com/en/product/cylinder-piaggio-200-cc_41470800

I thought the Serie Pro kit was simply the Piaggio original cylinder with an upgraded GS Piston. It appears the barrel is not Piaggio but a Taiwan copy.

They also sell a P200 barrel without piston, just by itself:
https://www.sip-scootershop.com/en/product/cylinder-200-cc_41470710

The descriptor for this barrel by itself says "Grade D - adequate repair" and does not have the Piaggio logo on the item page. I thought this was weird cause it was the same barrel depicted for both the above. I am now thinking this is the Taiwan copy barrel with casting issues which is also included in the Serie pro kit with GS Piston, and the only way you can get the piaggio original from them is to order the kit with the ASSO piston. So if you want to get the Piaggio barrel with the GS Piston you need to order the original kit with ASSO piston and the GS Piston by itself.

You have a lot of options now. Your original rusty 200 cylinder could probably take that GS piston.
Cancel the Taiwan replacement and get an iron Polini 207. Just like stock reliability when set up right.

^^^^Someone mention cast iron Polini kit?....

I've got i believe the piaggio original cylinder already on way. I ordered the piaggio kit with asso piston. Too late to cancel. Another time on the polini!

And yes I've got the original rusty cylinder i may do something with as well if i can't get the exhaust stub to thread on this defective one. Already took the dremel to the fin area to widen it to fit the stub. Still couldn't get it to thread on and it even felt like the threaded section is not even or right thickness cause the stub just doesn't want to sit flat to start threading on. Gonna keep widening everything a bit more cause one section still feels like it's blocking the stub. Regardless even if it won't thread on, even more reason to use the cylinder as an experimental one to see how wide i can get the exhaust port before breaking through. This would give me a better understanding if i want to go wider on one of the usable stock barrels.

Still waiting on replacement cylinder. International shipping is extremely slow lately.

But I did get the new cruciform from scooter mercato and went to assemble the gearbox, but realized the selector rod needs replace cause it won't thread on smoothly to new cruciform. Thread is slightly damaged.

While I was in there examining the threads I noticed some damage to 2nd gear as well. The inside surface of 2nd gear where the cruciform slides into and out of gear has some chipped/raised edge damage in the slots where the cruciform locks into place for 2nd gear. Those fractured sections are pictured below.

Bummer... Good find though! Shifting is going to be much smoother!

Yeah. Not sure if it really is an issue cause the cruciform doesn't even contact that surface of the inner ring, but when I noticed it, I took a dental pick to it and was able to pick off a flake of metal. So I figure its better to replace so that any other flakes of metal from those sections don't fall off into the engine. Not even sure how those fractures happen given the cruciform doesn't contact that section. I can't even see that lip of metal on any photos of other P 2nd gears online so I'm guessing it was an old gear cast from the 70's that they replaced at some point.

Ordering these parts from Scooter Mercato cause my replacement cylinder is shipping excruciatingly slow! It's taking the grand tour of Germany right now. 2 days in Gersthofen, 2 days in Munich Airport, 2 days in Frankfurt, now 2 days in Koelne. I wish I got the same vacation!

I've found that when it comes to scooter parts, patience is key. I'd love to just go down to AutoZone and pick up whatever I need, but niche machine means....patience....

I'm just thankful we don't have to make our own parts!

Cogs are fine. Clean them up and put them back in.
Selector shaft threads do get damaged. Lot of strain on them. EFL ones seem to wear even faster than the old type. I use a new one with every new cruciform. If the cruciform breaks off the shaft at speed you'll most likely die.

Still waiting for a German delivery myself. Been weeks already. And not exactly far. If it doesn't come soon I'll be recyling some old parts to get running again.

A certain German delivery took a month to arrive for the Orange Unicorn.
Just hit the doorstep a few days ago.
Woulda bought it state side - but it was custom made - of thin stainless - two walls thick - hand rolled on the thighs of a German virgin.
Well - that's not completely true - cause it was tig welded and that woulda really burned.
Anyhow: That was a damn good find.
It matched my experience - and you explanation here does as well.
When I built my EFL transmission - wrong needles would spin fine - until the counter shaft nut was torqued (one next to the clutch cover).
Then it would bind.
They measured the exact same length - but that little end detail was present - and it was all it took.

Nice one Swiss.

A month is pretty quick for one of those rare specimens. Update your own thread. Bet you're excited to see what that does.

Smells like Pipe Design Spirit...

You were correct. It was apparently flashing left over from casting. I took the dental pick to those fractured overhangs and was able to scrape them all clean and flush to where they were supposed to be. Guess the Italians were rushing home for pasta that day in 1979 and threw this gear into the pile without cleaning it up after removal from the cast!

Ok I finally got a piaggio original cylinder with no defects/issues. Dave @ Scooter Mercato came to the rescue. I ended up with 2 defective cylinders from SIP both from the Taiwan manufacturer (both refunded.. so I basically just paid shipping costs for a GS Piston from them). When the piaggio original arrived from Mercato, I recognized in 2 seconds why these two cylinders are defective and have holes where there shouldn't be.

The Piaggio cylinder has threads cut about half inch into the stub/exhaust hole, and the stub hole drilled for the threads ends right at the bottom of the threads. These Taiwan cylinders, the threads are cut 3/4" to an inch deep, plus the stub hole drilled was drilled another quarter to half inch below the end of the longer threads cut. This means that stub hole is drilled about 1/2-1" deeper than on the piaggio original cylinder.. which is why they break into the mounting stud holes. So fair warning to anyone reading. Do not order the Serie Pro P200 kit with GS piston, or the P200 barrel without a piston from SIP as both of those contain the defective Taiwanese made P200 barrels. Hopefully after my two refunds from them, they will go through and check all their remaining stock to remove any other defective items from their stock.

I'll post pictures later this week when I get a chance. Busiest week at work.. Super Bowl 55!

Taiwan P200 Barrel

Stub hole drill depth: 15.16mm
Exhaust Stub thread depth: 9.76mm

Piaggio P200 Barrel

Stub hole drill depth: 7.66mm
Exhaust stub thread depth: approx 7.5mm

So the Taiwan P200 barrels get their exhaust stub hole drilled about a quarter of an inch deeper than they should be.. which leads to breaking into the nearest mounting stud hole.

Used the worse of the defective barrels to make sure my target exhaust width wouldn't break through into the mounting stud holes.

Stock exhaust width measurements for this barrel:

arc width: 39.64mm
chord width: 37.33mm
exhaust width percent: 56.14%

Target exhaust width percent: 65%
chord length of a 65% exhaust width = 43.22mm
Arc length of that chord length = 47.06mm

So I had to widen the exhaust by approximately 7.5mm total and 3.7mm each side.

This was accomplished without breaking into the mounting stud holes, but as pictured, the widened exhaust passage is shallow and a venturi instead of a deep wide opening. Going any deeper on those interior walls would have definitely broken through stud holes.

When I get back up to NYC next week I'll break out my narrow calipers to measure exactly how much material thickness is remaining between stud hole and exhaust interior wall to get an idea of just how close I got to breaking through. Once I get this in-depth picture of my tolerances I'll apply same principals to the good cylinder.

It's going to work. If you screw in the exhaust stub tight, it's possible to Dremel through it to smooth out the transition. Get it all tidier and symmetrical, as far as possible with the angled outlet.

The GS piston windows might need some work to line up better.

Don't forget to chamfer all ports top and bottom. They do look a bit rough.

What will the final durations be?

I'm not actually using this cylinder. I just dremeled it rough and fast to make sure it wouldn't break through. When I go to do the actual cylinder I will definitely keep it smoother.

I've been curious about what work needs to be done to the GS Piston in terms of dremel work to smooth out and or optimize the ports.

And as far as that test cylinder, I profiled the exhaust port and raised it approx 3.2mm to hit 180 degrees, and all the timings measured on that including rotary valve would be:

1mm squish
119/180 transfer/exhaust
31 blowdown
121/74 rotary timing with 195 degree admission.

I would just use that cylinder. Tidy it up a bit and try it. If it is too much, then do less on the next one.

What exhaust pipe?

The GS piston will need all three windows raised for a 60mm crank, how much is 1.5mm + any base packer + a bit. The window sides usually need some alignment but you will need to dry fit in the cases to decide how much.

Quite a bit off topic, but that really looks like a Joy Division t shirt you're wearing

Good catch! Close to a Joy Division shirt..which I would wear if I had one, and why I bought this one when I saw it!



https://www.scooterworks.com/T-Shirt-Scooter-Pleasures-P13563.aspx

SIP Road 3 I'll have to take a closer look when I get to installing everything. I did just take some measurements of both the GS Piston and Meteor Piston ports to compare. I'll post pics and measurements later, but the summary.. all of the meteor piston ports are larger than the GS piston ports.

I know this is not accurate area increased calculations, but just basic comparison of same measurements.

Meteor Piston
width: 66.25mm
height: 82.55mm
compression height: 48.25mm

GS Piston
width: 66.17mm
height: 82.75mm
compression height: 48.86mm

Norrie Kerr talks about the compression height of a piston and Im probably calculating this wrong, but it seems he was saying compression height is the length from the top of the piston crown to the center point of the cudgeon pin. I measured the length from the top of the cudgeon pin hole to the top of the piston crown, then measured the width of the cudgeon pin hole, cut that in half and added it to the previous measurement to get my compression height numbers.

EDIT: revisted compression height and I measured wrong. It is not top of piston crown to center of cudgeon pin, but edge of piston crown to center of pin. So I should be measuring from where the piston crown meets the piston wall.

And while I was out in the garage taking piston measurements, I also took measurements/tracing from the Piaggio original P200 barrel.

38.9mm exhaust height
approx 47.42mm transfer height
gives a 165/128 and 19 degree blowdown timings untouched with a -1mm squish.
37.88mm exhaust width = 54% width.

widen the exhaust to 47.06mm to get 65% exhaust width, raising it 3mm to get 177/128 24 degree blowdown. Plus profiling the exhaust to be squarer at the top and slightly rounder at the bottom for ring safety while still getting the 65% width increase.

Just got a care package from Greasy with p200 oiler carb box and front hub that he was kind enough to sell to me. He was also very generous with lots of additional extras included in the box.. tons of gaskets, seals, fuel tap lever, patches, beer coozie and even a vintage porno mag! ha!

Now that I've got the carb box bottom I can finally finish rebuilding this engine and get it ready for testing.

The v100 project has been keeping me busy in the meantime and that is almost back on the road. It will be a productive few weeks if I can get the p200 running on test bench with having just gotten the stella running in good shape and the v100 back on the road all in the last two weeks. I guess it makes up for the past 2 years of turtle pace!

p200 air box complete from India--advice?

So this thread and Safis mentioning how rare these parts are becoming now that they haven't been made by piaggio in a few years... got me revisiting my carb box to see if I could rescue the seized parts and save it all for reuse another day.

I did just get a working oiler box from greasy when I gave up on this one after trying unsuccessfully to remove the oiler valve a few months ago. But this time I was able to finally get that oiler valve out with tons of heat and much effort. I did put some scratches into the carb box bottom where the oiler gear rotates and on the seat where the valve tightly slides into. I think I can clean up those scratches with some light sanding and everything will work with a deep clean and new gaskets on the oiler valve. Was also finally able to remove the plastic bushing holding the spring and bearing into the box bottom which proved elusive last time as well. Tons of heat softened it up. I'll be replacing the plastic bushing and now that I have the bearing out, I can finally measure it to see if I can find suitable replacements locally, given these bearings aren't sold on sip or listed on Mercato's website. For anyone who is wondering... bearing is 3.95mm diameter. If you want to throw money at obscure random small parts.. here is a titanium ball from mcmaster that could be used for this part:
https://www.mcmaster.com/9288K33/

Now I have a spare oiler box and parts for if/when I need in the future!

Pulled this engine back out to finally finish off and get running now that my other projects are in a good spot and not consuming 100% of my mind.

I cleaned up the original carb box oiler hydraulic pump seat which I had put some gouges in while trying like hell to remove the hydraulic pump from the carb box. Light sanding 400 grit to smooth out the gouges and then a quick pass of 1000 grit to make it nice. With everything cleaned up, the hydraulic pump still would not fit into the carb seat without way too much heat to expand the seat. So instead I took a small piece of 400 grit and lightly sanded the hydraulic pump all around it top to bottom, removing some imperfections that were in it and finally got it to slide into it's seat in the carb box with the right amount of resistance instead of being impossible. Once I add the o-rings, they should do their job of sealing the hydraulic pump so that the oil stays in its channels and works properly in the oiler.

Mounted the crankshaft so that I could finish off with more accurate measurements of the brand new piaggio original barrel. This one was the 3rd one.. got this from Scooter Mercato after the first two from SIP had casting issues as mentioned previously. All my previous measurements for barrels are discarded.

New measurements as follows:

Exhaust: 38.95mm from deck
Transfers: 47.44mm (avg) from deck
PBT: 0.26mm
Stroke: 59.76mm
Conrod: 110mm

(These valve measurements are after the pad has been grinded wider)
Rotary Open: 49.08mm (avg) from deck
Rotary Closed: 26.96mm (avg) from deck

Current timings:

Exhaust: 162 degrees
Transfer: 124 degrees
Blowdown: 19 degrees
Rotary Open: 122 degrees
Rotary Closed: 76 degrees
Total Admission: 198 degrees

This is with zero base gasket. With zero base gasket, the meteor piston rests approximately 2.56mm above the bottom of the exhaust port when the piston is at BDC. This means if I wanted to get the piston flush with the bottom of exhaust port at BDC, I would have to raise the cylinder 2.56mm which would make the squish on my zero squish head way too large at 2.82mm total. So I think the piston will sit wherever it sits at BDC in relation to the exhaust port bottom.

I'm thinking my total squish should be 1-1.1mm? So that would be a 0.74mm-0.84mm base gasket.

With a 0.74mm base gasket to get 1mm squish, and absolutely no exhaust grinding, this would be the timing:

exhaust: 165
transfer: 127
blowdown: 19

rotary open: 120
rotary close: 75
admission: 195

I'll need to go back through this thread to remember what was discussed in terms of exhaust grinding for target timings, and exhaust port width shaping.

Exhaust Port width I labeled wrong in the port map scan uploaded. the width on that is the arc width, not the chord width. The exhaust currently has a 35.51 chord width and is 53.4% width. If I wanted to target 65% exhaust width, I'd have to open up the exhaust 5mm on each side. Not sure if that is possible.

I had the same issue on exhaust width and stud placement, I widened mine out as far as I was comfortable with and moved on.

I did a practice Dremel a few months ago on one of my defective barrels and i think i was able to get to target, but was not comfortable doing a deep cut, so i ended up getting there by cutting it into more of a trumpet shape where it was more shallow a path until the end where it flared out quickly to get to the target width. I'll probably do something similar and call it a day.

Found a video that has a few nice tips I hadn't seen before about optimizing the stock p2 barrel. Specifically smoothing out the boost port with a long strip of abrasive cloth?

It's alive! Started up easy once it got fuel in it, and the idle screw adjusted properly. Sounds great! Left the jetting fat for now till I get it in a frame.

5-10 hrs of cylinder and piston prep work 3 weeks ago and just when I went to start it, I broke my only kick start lever. Had to put back on the shelf for last 3 weeks until new one arrived.

I can't remember the exact details, but I think it is set to:

179/125 cylinder timings with 27 degrees blowdown.
198 degrees rotary admission

The actual measured squish is 1.38mm.

Work done...

On the stock P200 barrel, I widened the exhaust port to 65% width... which was about 5mm wider on each side I think. Its a wizard sleeve situation, not a deep pathway in order to avoid the stud holes .

I raised the exhaust port somewhere around 4mm. I then decked the head and the cylinder top flat. So that probably took a little off the original PBT measurements which is why my timings are a little higher than targeted. Also buffed the crap out of the exhaust port with progressively smoother dremel sanding bits.

I then used 100 grit strips of emory cloth to smooth out the boost port best I could for half an hour or more.

Next, I custom cut base and head gaskets to hit my target squish with the 0 squish MMW head I used. The custom cut gaskets are what took the longest!

Finally, I dremeled the GS piston ports wider and raised the openings closer to top of piston to get nice big openings. I then used the same emory paper to make real smooth rounded edges to all the piston ports, and finished them off with progressively finer sanding bits on the dremel.

I did not do the full ThatScooterThing package.. I didn't cut the side ports out of the barrel skirt, nor did I match the cases to the barrel or do any other case dremeling besides the rotary pad lengthening for 198 degree admission.

Timing set to 17@idle to start. Idles great at 1100-1250. Definitely rich as it dies at 10 min idle once it gets warmed up and the plug fouls.

Still need to drill the carb float passage as i left it standard and have big fat mj in there probably not getting full flow out of.

Carb randomly came with this jetting:

190/be4/116 and 50/120 idle.

Current starting point on jetting just to get it running:

160/be3/125 and 50/120 idle.

That's 9 mj sizes larger than stock to account for 60mm, larger rotary, and sip road 3 exhaust. I might need to go up higher on mj for all those increases. Once it's in frame and running I'll get better sense.

I left the fat idle in it just to be safe on first start. First things first.. Idle going back to stock p200 idle of 55/160. Since this is a stock cylinder with only long stroke crank and more rotary timing, I'm expecting 55/160 should still be good.. Or if needed only one size richer to 52/140.

How the hell did I not see this thread...?

So great to see this build!

Running well by the sounds of it. That's been a while coming. Try getting the idle slow enough to count and then you know there are no air leaks.

That Chinese cylinder is rough but works. With the now big exhaust port its going to feel totally different to stock. I expect it won't be winning any races with the smaller transfers but will have a very noticeable surge as it comes onto power. Would expect peak to be about 7000rpm but over run may be less flexible.
Next time you have the piston out, the gas flows from inside to out, so the silky smooth port entry should be the other way around.

That jetting AC190 BE4 116 is German stock jetting for a 200. This will not suit yours; exhaust port is now too big. You might want to keep the BE4 but with an AC120. 50/120 should be good to get going with.
Better not running with that air filter. T5 one is ok. Vortex is preferred. None is a good compromise.
How long before the frame will be road worthy?

Ah damn.. I aimed the piston smoothing wrong direction! didn't even cross my mind.

I could swap it into my current stella at any time just to get some runs on it and see how it differs. My plan was to wait till i'm back up north middle of next month and get the matching p2 frame back together and running.. which requires a couple weeks of work. Some rust proofing clear coating on the underside, and replacing the fork race/bearings plus tank cleaning/etc then get everything back on plus a bunch of new electrical parts I do not currently have.

Or there might be another frame option down here that I am looking into, just when I swore I was done buying more vespa projects for a long while!

So who knows.. next week if in current stella frame.. a couple weeks if that option down here comes through, or a couple months if I wait till I get the frame this engine came with back on the road.

BTW, I don't think this cylinder was made in china unless thats where piaggio original parts are made there now. The 2 Taiwanese ones I did not want to take a chance on. Those are on the shelf in NY. This was the piaggio original purchased new from Scooter Mercato, which itself could be made anywhere these days, or it could be made in Italy. I have no idea, but it is the OEM barrel.