Modern Vespa

Numbers on those charts are not wrong, just only part of the story with the rest of the factors affecting them +/- 5 degrees. So transfer duration for peak power at 7000 rpm somewhere between 115 and 128 will work. For 8000rpm same. 9000rpm same. Getting the degrees right is one thing. Angles, crank, inlet, exhaust (port/pipe), bore, stroke, weights can all wildly change the outcome. Experience and experimentation.
Best approach is to decide where and how much max power you want and hope you have enough torque left to get there.

I think another 0.3mm on the BGM will be enough for the last try. Torque is even more important to your set up. Low gearing helps but still need the torque.

Although for the science maybe taking it up to 128 degrees after testing 126, could be good information for the record. Once the tuned MHR is on it probably won't come off.

^ Makes sense. Did you mean this while holding 186 Exhaust or lifting them both.

As it turns out - I've got a cross country trip planned coming up in just over a week - just not on the scoot.
That said - the scoot is coming with me.
Time permitting on the weekend - I will pull the motor and give it a servicing including clutch discs - and a lift.
TBD based on available time.

*Edit: Question: given that the Polini box has moved my peak down to ~7KRPM, would it be more effective to get more aggressive with my grind shaping and square up the exhaust port top or do an overall lift?

What would be the trade offs between the two?

Gents - and lady.
Can y’all educate me on what and when these felt like gaskets are used under a cylinder?

Do they pack down over time?
Are they a known good or bad thing?

Normally only use aluminum ones with some high temp rtv.

Have wondered about using these for very subtle adjustments.

Those look like factory gaskets, I have a few that came with new gasket sets ordered.

Put one in the vise between a couple of bits of flat sheet metal and do it up tight. Take it out and measure.

Christopher - I think they came with the kit. Yes.
Ginch - good thought. I was more curious about why one would choose to use felt - what are the trade offs kinda thing. Like you - I imagine they compress - but not to 0. And I would think they seal pretty well?

Has anyone else chosen to use these with good or bad results?

Tks all!

Better than a vice - measure squish before... add one (as needed) and retorque the head. Measure squish again (hopefully the value you are looking for)...

If they torque down and don’t deform then surely they are up to the task.

But it’s squish you are trying to modify - so surely best to measure that?

For what you're doing they will be ok. For long term I prefer aluminum.

Try the lift before changing the exhaust port.

Cylinder off yet? How's it wearing?

Thanks guys.

With the trip so close - it woulda been reckless to get in to the motor with just a few days before exit.
I mean the scoot is running so well!

So after dinner - I went to the garage to organize things - and...
decided to pull the motor while I was there.
By midnight - the squish had been measured Pheas' style (you can see the marks) and the inlet had been port matched and opened a little to the manifold.
🙂

Interestingly - While I had dry fit and measured squish last time at .8 (I think) when I re-measured I got 1.0
I am assuming that the generous layers of Hondabond added .2mm - but using the buzzwanlge and a feeler gauge - I got 181° of exhaust port timing.
That is within 1° of my ring measure method (not 1mm - 1°).
That's closer than I could have hoped for really.

So I will refit it all tomorrow.
I have a long list - including adding a bung on the exhaust for the 02 sensor, and doing a paint patch job where I have bare metal.
It won't be pretty - but it should keep it form getting rusty if it sees some rain along my way.


A piston top that even Jack could love

Inlet has some room to grow - so I used the Voodoo stuff some tape in it method - only I put it sticky side up so the dust sticks to the tape.

Ready for re-assembly

Not a whole lot of sealing going on here is there? Or is that an illusion?

That high res screen Ginch has at the office busted me.
That was once filled with JB weld.
On the second or third time replacing the cylinder - the JB came out with the cylinder removal.
Since that time - and through a handful of cyl replacements - I have swapped to filling that indentation with Hondabond.
Ugly - I know - but its worked so well I had forgotten about it.
Moral - on shallow indentations - RTV which stays flexible may work better than JB.

¯\_(ツ)_/¯

Note a "small indentation" on your flywheel too. Yah big bully.

Question - why don't y'all get the cases built up via tig?

https://www.youtube.com/watch?v=ttMgQoIHJLs

At least the piston is looking great. Right on the very leanest point of perfect, exactly where you would expect for CM jetting.
Is the cylinder back on yet? No time to waste. Will need a slight upjet and a few runs before the trip.
And, need to get the BGM experiment done. After a lap of America it might really be done.

Pheas' - not really sure what happened to that response.
Funnily - I had watched that video previously.
Good learning - and loved his arm rest!
Plan to build a welding table when I return.
(I might have acquired a TIG welder - just haven't opened it yet.
Will take a bit of practice before I try it on my cases...)

Cylinder is on.
Base gasket was .5 previously.
Didnt have a .8
Managed to find one .7+
Calculated timing is roughly 125.5/ 182.5/28.5
Maybe a half point higher.
Suspect it will be to my liking and plenty torquey for touring.
Perhaps will require one richer setting.
We'll find out.

Have some other work on the bike before I re-assemble.
All sorts of small touch ups and repairs.
Also have some clutch discs, brake pads and disc that will all go on before exit.
All those speed runs and 60 to 0 stops have taken their toll.
Gonna be a marathon before getting outa town.

Back - unloaded - and riding again.
Good to be home.
Where we last left off - I had lifted the cylinder a hair more.
My rear dyno says Im up in HP but little less torque in some areas.

Will make sure I am fully tuned in and do a few speed runs - and post my port timing info.
In the mean time - few questions for the crowd - I'd welcome some feedback.

- When I went to the Polini exhaust I added springs. I suspect the springs are creating some weird noise - sort of a washing machine sound. (HA! I am that guy calling the shop saying my car sounds like a washing machine - what's wrong?!). Sort of a surging sound that is unpleasing to my ear. Is this common - is there a cure y'all like?

- I have the 28mm carb on now - replaced the 25mm. Question: all things remaining equal - will larger carb lose some torque in trade for peak HP - or is it a linear gain with larger carb if previously under-carberated?

Like you've never been away. Good it all still works after the exhibition tour. All sorts could have happened and didn't.
So, final set up of BGM, then onto Malossi?

Bigger carb (correctly setup) should give more torque. As more torque comes from burning more fuel.

GSF should show up if anything is missing. Weekend weather not looking great for test runs. Pretty much the same here.

Damn miracle really. Got it - and helpful. Tks for weighing in.

Lifted cylinder requires me to shift up to front of seat and lean over handle bars.
Said that to Chandlerman when in Nashville.
Response: "what's your point - isn't that normal?"
So I altered riding style and got on with it.
Didnt take long to think: jeez - this is great - maybe just a BIT more HP.
I am such a knuckle head.
Somewhere in this thread - Ginch noted - why dont you just decide where you want to be in the end and go right there rather than take one step at a time.

No idea how crank (not even the PX thicker taper) has held up to all this.
Just hope to upgrade before I throw the rod through the case wall.
Seriously y'all - these things are pretty damn rugged.
Hat tip to vespa engineers and their Italian vino.

For all the seized melted pistons we have all managed - Swiss/Christopher/me/Others! I am looking at you! we are lucky the bottom end holds up so well to such questionable tuning work.🙂

Jack - others - pipe up on the following:
All the tuners seem to end up with reed valve option.
What are the negatives/tradeoffs of going reed?
Low RPM torque?
Noise?
Whats the gig?

Thought it would work. Gives it a bit more of a classic power band hit. Can get addictive. Malossi will hit harder when tuned Might find the crank limit yet. I just brought a spare crankshaft for my 221. Don't need it but it's ready. Rotary is actually better than reed. More max bhp (for the same area) and no moving parts to snap off and fray. However, reed has less blowback, making jetting easier. Reed has more mid power. And the big one, reed is bigger. Much bigger. I don't like reeds. Noisy and expensive but there is no other way to get the big power. No going back either........ but who would want to?

Don't want to put the moz on you, but my recent BGM rebuild was due to a blown big end bearing. The guy that gave me that advice was not saying your first Vespa should be a 306, he was really saying just skip the steps where you think an Indian stator off ebay looks just as good as the one you see at the big shops. In my case I kept thinking that I wanted just to be able to go just a little bit faster. Think you should be fine.

I think the thing with reeds is that you can get a far bigger intake than the rotary, as Jack says. Plus it frees you up regarding the crank... like a bell or cut back crank or cut back case where there is plenty of space for gas to flow past the crank rather than through.

I often hear the one about rotary being more powerful than reed, but not convinced that it's our style of rotary that they're talking about. If you search for a rotary valve, this is the style that comes up and this is the style that's most often discussed. Allows a big opening and the ability to alter the timing with a disc swap.

Our style of rotary is actually better than side entry rotary, as the flow is inline with the piston and feeds each side equally. The issue with our inlets is they are so small. Awesome piece of 2 stroke engineering, just in miniature.

Piston ported without reeds is the worst inlet design ever. Bar none. Period. Just though I would add that for comparison.

LOL! I'd forgotten about that. You don't even realize you're doing it after a while, until you jump on a bike that *doesn't* have that much power and just feel silly-looking as you throw your weight forward for no reason. Not only are they rugged, but if you look at them in the context of being something that was going to be cast, then finished by a machinist, you realize all the subtle design decisions which boiled down to, "Do we make this optimal from a performance perspective, or design it so that some guy standing at a drill press all day will get it right almost every time?"

The Vespa engineers did a really good job of that, IMO. I compare it to the 1962 vintage outboard that came with my boat. I opened it up a little bit and realized that the thing was designed with no consideration whatsoever of the fact that people might need to work on them at some point down the road. And don't even get me started on the abomination that is non-metric measurements... Jack already answered, but the trade-off's of reeds are:
- more potential surface area, and thus airflow, torque & HP
- less blowback
- more moving parts -- reeds wear out and have to be replaced periodically. Rotary valves last effectively forever, so long as you don't gouge them too bad
- higher cost
- more crank options
- no intake timing to worry about/tune for

They have a slightly different sound than a rotary, which is noticeable when the cowl is off at idle, but it's pretty minimal. Some people say they're noiser, but that could be blaming the reeds for the result of the reeds (more flow and more power), so take that with a grain of salt. In my testing, the difference between a reed and a rotary on 187's was 104 vs 201 dB, so well within the margin of error, I'd say.

Funny, I was just looking at a dyno sheet for a Pinasco 225 with reeds on Facebook. Guy says he did no port work just normal cleanup. He put v force 4 reeds in for the intake. Different pipe but still, makes me wonder if I'm leaving a lot on the table not going to a reed. Maybe their dyno is really optimistic? That's a 20 - 30% gain at 6500 rpm over mine.

https://www.facebook.com/195581880638988/posts/1334752656721899/

Looks like he was already running a side draft carb, plus they swapped the crank at the same time, so more than "just throw on a reed."

Still, at some point in the turning process the flow into the crank case will be a limiting factor, and a reed, flowed or bell crank, and opening up the intake is the way you do it.

Hard to know my exact millage right now.
Maybe 4000- 5000? Wild guess.
Motor feels good - but have been struck by how well it's held up.
(nock on wood).

Great stuff on reeds y'all. Thanks.
So wadda bout the crank?
Which is the gold standard when using reeds? (Bell/other?)
Oh - and why do some choose the LML cases vs vespa ones?

Questions are somewhat loaded...
I have a spare cylinder/piston & I was also offered a set of LML cases that Vader had been working on that have been ported for reeds.
Could build up another 187 to have as my back up without too much investment.
Random ponderings...

I always thought it would be interesting to run a LML with a 2 reed setup side draft. Then put in a 4 reed setup and see the difference.

I did my first couple of porting projects with the LML reed block, a 24/24si, and a DR 177. I got that to about 14 HP, but it was always a bit touchy. That flat little reed block just can't be opened up enough to really move much air. The VForce 4, on the other hand, I'll guesstimate has many multiples the flow area. That adds up , to the point I can run a PWK 34. It's super fast. Passes everything but a gas station

Ha!
Well - I hadn't even considered the different types of reed blocks.
These are the cases I was given.
My apologies for showing them when not Vader clean - have been in storage a while.
Some nice porting work was done on the inlet.
Does look like they may have a repaired crack that might need a closer look.
Assume there is a gold standard read block for side draft that would make sense. I don't have the original read block for these cases.




Will have to clean up the repair area to have closer look. appears to me to be a weld - then covered with some epoxy - presumably to stop any leaking.

You can see the crack starting at base of the oil fill boss

With the size of that reed opening, I don't think it had a stock reed setup anyway. There's no guts there, would you be better off finding a used motor for all the miscellaneous parts?

Maybe - but...
- read block - aftermarket
- electronic ignition...
- fancy crank that is shaped like a bell or something.
- have a cylinder and piston
- Whodat ruined me by introducing me to the EFL transmission - so shaft/gears/xmas tree/shift box all new.

That leaves the clutch cover and kick starter from an existing motor re-usable.
🙂

Now if you only had a really cool old patina’d Allstate to put it in ... oh wait

That case is the same as a rotary PX150. I have a couple of the LML reed cases and have found them to be pretty good.

It does depend a bit on where you're going with it, if it's 'just' a spare motor then it'll be absolutely fine. If you want a bleeding edge build with twin overhead bells &/or whistles, then maybe not so much?

So where are you going with it? You have a 200 case tucked away don't you?

My approach is frequently more Jackson Pollock than it should be.
Cases were gifted - but not a must to use.
Don't want to really invest time in something that would be just so/so.
Will have this spare 187 cylinder and piston.
Perhaps these aren't the right cases for the build.
For a 187 - what is the gold standard for cases?
(is the answer to this P200 cases?)
🙂
Will have to have a close look at the crack in any event - that may make them a non starter.

Indeed...

That one is still slated to be an electric screamer.
Of course - it needs a bit of body work first...
Should have it done within the decade.

[quote="charlieman22"] No. They get a 225 Pinasco for touring and easy setup or Malossi MHR 221 for tuning sport madness.

Guess which one I’m asking Santa for ;P

Malossi cases would have to be the high point of case-dom. 150 cases would still give you the option to run a BFA 225 cylinder if you wanted.

Those are rotary cases that were converted to reed.

The reed-designed LML cases have a very different intake.

I also included a shot of the stock two-petal LML reed block for comparison.






stock reed block (with porting plan)

Looking into the MMR reed block for RD-350 VForce4 reeds

Ahhh!
Thanks gents.
Now I get it - LML (later?) cases came as reed block design.
The ones I have are (older?) rotary cases that were modified.

Still following along here.

LML had a partnership arrangement with Piaggio and they cast standard PX150 cases - amongst plenty of other parts for Italian produced scooters.

After the partnership ended, due to the terms of the arrangement they were able to keep producing scooters. At that point they started making the reed cases... the first significant upgrade to the design since they moved away from piston porting.
LML were also the reason Piaggio took up PX production again after announcing the end of the model. LML did pretty well in Europe once the main distributor there forced them to address the quality issues.