Modern Vespa

Cool. didn't have the whole story - coming late to the scooter scene...
I had the sense that "LML" cases were preferred by tuners.
Turns out I was half right ^.

So if you are going with "small block" cases as some like to call 'em - then LML reed cases have some upside.
The ones I have are rotary - ground out for reed.
Perhaps those wont be the base to utilize...

¯\_(ツ)_/¯

While it looks pretty big, the intake casting is not big enough for say, an RD350 type reed to fit into. It does mean though you don't need to worry about breaking through when opening up a rotary case.

but at the same time, all the guts inside the Piaggio cases are higher quality (and stronger). If you want the best of both worlds, swap in all the parts from inside a PX EFL engine into a Stella case. But good luck finding a PX EFL engine in the US. Most likely the engine would have to come out of a 2005 PX150.

Thanks WDC.

Ok - back to the current build!
There was a ride here this weekend - SWARM La.
Great route - like a best of for Los Angeles:
Mulholland / Topanga Canyon / Sunset Blvd.
Went to meeting spot by highway.
65MPH whole way.
Scooter just singing.

Arrived to find MJ Rally up form San Diego serving up donuts to the early arrivers. qascoot - no buttermilk bars - but I looked for one in the box!
Hebert was there as well with the trusty Bajaj.
Good crowd - though didnt really know anyone.

Had my usual 3 stages of a rally.
1. Oh - isn't that scooter with a side car cute.
2. Oh man - why isn't he lining up at the back?!
3. Wholly cow.

We drove some crazy curvy roads - orange unicorn wound its way to the front group and stayed there for the ride.
Much fun was had.

Just as I got back to the house after 80 something miles - the exhaust got really loud.
Over coffee this am - took a look. The Polini is dead...
Pulled out the well worn SIP Road II and did a little clean up.
See below.

Boy I can tell such a difference between the two.
SIP has more revs in it - at least 1000 - of usable power.
But it doesn't have the Polini's grunt.
No second gear wheel lift threat here.


The Pollini when I took it off - gracious - it was unhappy.

Out came the road II - and the grinder...

That center divider was just rattling around free inside - so I welded it back in place.

You don't want me doing your kids stitches

The Orange Unicorn leaning in. Rider up at the front of the seat. She did me proud in the twistys.

Quite a job on that exhaust CM!! I mean both of them but in different ways...
How old is the Polini? Just pretty new isn't it? Funny I read something the other day about more revs from the Polini... but maybe it was a poor translation?

Chuckled at that.

Polini is all but new.
No more than 150 miles.
Crack appears to be self inflicted.
Though I have to say - the box is made of tinfoil.

There is very little clearance for the Polini with my leaner subframe.
While it can only pivot away from the sub frame when the suspension compresses - on return - it was probably hitting.
Just before the ride I softened the rear shock adjustments.
Felt great - but I apparently allowed the return from compression to go past the resting point.

Polini really looses steam over 7200 RPM - and has weaker over run - but is punchier at 5K RPM.
The SIP Road II pulls to 8200 - which is fun - but I want my torque back. Just too thin below 6000.

Speaking of thing - kinda shocked the polini just disintegrated like that. Geez. Metal normally bends and stretches a little - this just cracked like glass.

I'd like to put a Polini back on (or maybe some other fancy box).
Mightneed to indent the pipe - as I don't want to move the subframe.
Wonder how that would affect the resonance.
Feels like some experimenting is about to go down.

Maybe I will try to weld that catastrophe of a box back together and put a dent in the pipe to create more clearance where the mark is - see pic below.

Wadda y'all think?


So this is where it was hitting - really doesn't look like it was striking very hard. What would happen to my resonance if I heated this area and spooned it in a little?

Quite a hoot by the looks of it. Seems like you're settling for holly cow.

Not sure that exhaust was touching enough for that kind of damage. Might be restriction and frequency.

Time leave the exhaust cracking and falling off to the Lambrettas and to try an actual expansion. Left hand side with a quiet silencer. Won't be any louder than a box but will go properly. Especially when the Malossi 187 is on.

If you specifically want a box, first attend to whatever caused that issue - clearly not wear and tear. But it might be worth giving the Megadella a try. You would need to contact them to work out which is best for your timings (and the MHR timings too) as they have a range of box types. Think it has to be through FB, not sure there is a site.

you would have done better losing the centre divider.... its a mechanical baffle and resticts the power output

Well - that is a shame.
I am always up for a little experimentation... I rode near a lotta guys with expansion pipes & silencers.
Most seamed about as noisy as mine - maybe a little less Harley thump to them than mine.
I don't mind the noise level with silencer - comparable in my view.
But... Wouldn't this put a couple HP of peak on at the cost of it at 5K RPM?
Is there such thing as a torquey pipe?
That might be cool - and right side exit pipes look like they would avoid any interference with subframe. Is that a thing?

Was surprised by how it looked absolutely shattered rather than just bent or cracked.
I should have noted: after running rich for my entire trip - I got back and received the infamous EK rods. I put in the 28 on Friday before the ride - and the bike just screamed. I then rode near WOT for 30 min on hwy to get there. Rode hard all day - and the shattering occurred best I can tell when I was on the Hwy home or just prior - had to slow for traffic and thought - geez - that's kinda loud... these are also cool. ironically - if they are same as a pipe in performance, then a pipe would likely be a better fit. On the other hand - looks like perhaps they are the answer to my question above "does anyone make a torquey pipe?"... Might need them to make it so the pipe sits down a bit lower and not so close to the frame... Will have a look at their offerings. Thanks!


Piece of metal was entirely missing from in front of bracket, & its true the hole is blown right where the pipe ends inside the box.

Oh know that is a bummer. Have seen boxes in the past have similar failures at the mount patch area like yours. Think vibration might be an issue. I've thought about a rubber vibration isolator between the exhaust tab and case bolt.

Great seeing you Charlie and the Orange Unicorn at SWARM. Missed MJRally and the doughnuts though.

Thanks. Was wondering if anyone had seen that kinda failure before. Kinda agree with what you and Jack are suggesting. Really doesn't look like it was hitting hard - though it could be combination of all.

Rubber mount is brilliant - of course!
Why do we have the only exhaust systems in the world that are solid mounted?
High temp grommet in the hole would do the trick I imagine.
Like that.

Meanwhile - porning the internet for exhaust systems.
Though I often use that term to describe endless dive in to the internet abyss for something - I should warn: Careful if you search FB groups for Mega Della. Just sayin.

Cheers.
-CM

Let us know what you find, interested in trying one myself.

So... The boys at Megadella (again - NOT Mega Della!) suggested their slx 8 coni mod 182904218 (pictured below).

Looks like this line is for:
- small block rather than P200 based builds
- comes in 3 flavors itself - one super torque - one less so - one higher rev

The recommended the middle one.
Geometry frankly looks pretty similar to the Polini.
Doesn't have the honking big expansion pipe going in to the box.

My take away is - the giant expansion is best for high RPM but you trade torque.
Ik,Ik, state the obvious - but prior to seeing their designs - that relationship hadn't fully sunk in (I assumed it was more about specific geometries and lengths).

Not sure I will find value beyond the Polini - though perhaps something subtle in its rev peak.
Anyone wanna throw in their comments?


Here is the Polini

Here is the one Megadella suggested. Looks like the pipe is a bit longer but shape and size seam similar

Bottom of the Megadella - doesn't have the cool looking expanding(sion) of pipe under the box like their others.

What method did you use to contact them?

You've never even tried a real expansion. Boxes are a compromise. There are all sorts of expansions and one for every job. I like pipedesign exhausts because they perform as stated. There are many others that would do the job. There are expansions specifically made for higher torque. Sure you could adapt the mounts to fit how you like.
Why would you not want more power?

You might be misreading me.
I'm not fearful of the mounting - its critical - but its just something to manage.
I Like the right side exhaust but it might interfere with the leaning mechanism at the tail - so traditional left side may be the call.

True - I was concerned about noise - but after being surrounded by 100 other scooters many with expansion pipes and silencers - I realized they weren't any louder - though I found them kinda tinny vs the thump thump thump of my box.

What really has my focus is power & torque curve.
Don't wanna be stuck having to shift down all the time - and then experiencing the "much louder than desired" effect 'cause I am at 6000RPM screaming along at 25 MPH... Nope - didn't miss this.
If I was building a 221 or > CC - there would be a lot of room for error.
Nothing like displacement to cure your low RPM torque woes.
With my set up - torque and HP at lower revs have a razor thin margin between knock your sox off wonderful and thisthingisapaininthearsetodrive.
Reticence on making the next move is wringing out enough knowledge to nail the Malossi build.

I really don't give a shit if the BGM or Malossi produces more peak power.
My real interest is in threading the needle with a killer build when I move to the Malossi. Wanna have min 12HP/8.5nm at 5K RPM. More is great - but that is the line that makes it dynamite to drive.

Off to porn the pipe design site.
Looks interesting.

.
Lemme try that again.
Love the peak power and the revs.
With cylinder lifted to .8 from .5, the subtle drop in power at 4K-5K makes me miss it.
Still rides terrifically - but that effortless throttle response to 1/16 of a turn has dissipated.
Polini box - tho not very durable... edged me back in - but of course leaves some top end power on the table.
Hard to know if the pre-res on a pipe would be sufficient - tho the peak would get a nice bump.

Ah - much better with a coffee in me.
🙂

Had a good look at the pipe design website.
Very cool products.
Small company - if you send them an email - the guy that builds is the one that responds.

There are two pipes that look like they would fit my bill.
Both snake backwards first - so that they don't come as far forward.
This looks like it would clear my subframe at the front.
They tuck neatly on the non-motor side - and I think it would clear the subframe.
I am getting some measures to make sure.

Below some tantalizing info.
Have to say - one thing that stands out with their posted charts: reeds make a big difference!
Hahaha - I went looking for a pipe and got hooked on reeds.
Seriously - what's wrong with me?


The Daytona - all snake like to fit under motor a bit while keeping the longer resonance length that apparently is good for torque. (little torquier than the Cobra below)

Tantalizing - and close match to my build. However - this is an old Polini exhaust. It's that 4500 RPM spot that is hard to know how it will translate to my riding style.

You need a new drug. Imagine this is you with your sidecar rig in the garage!
https://www.youtube.com/watch?v=N6uEMOeDZsA

I'm tempted, when I split my cases to just get it over with and put in a set of reeds. On the other hand I would like to see what I get out of an optimized rotary valve. If I went reed, I would have to get a 62mm bell crankshaft optimized for a reed setup.

Been awhile since we did some tuning.
Or posted some new dyno charts.
Or fabricated anything.
So I thought I would totally avoid the paying job and do a little of all three t'day.

Hate to waste stuff - and couldn't bare to see the oily cracked mess of the Polini in my junk pile - so I pulled it back out - and sprayed it down to see what I had.

What I had was a total mess!
Good grief - that thing had more cracks in it than a football huddle.
So out came the sander - all recorded in RGB for your viewing pleasure below.

When I wrapped up - I figured - might as well run some dyno speed tests with the SIP Road II before I pull it off - then put the Polini on and do the same.
Note: I am now on 11" tires - which while low profile - are at least 8CM-10CM larger circumference than the tires I ran all prior tests on.
Thrown off all the relative measures from the past.
So I will have to sort out how to adjust accordingly - but in the mean time - this is a great comparison of the two exhausts/ really captures it.

Oh - and one other thing - boy does that Polini sound great in comparison. Thump thump thump at idle is extra pleasing.


Bit of a disaster

Flap wheel applied indiscriminately - except over the logo - which I decided to detail for no apparent reason :-)

Some project Binky CAD work done to template the repair plate using card stock

Repair plate welded on - with some spot weld holes near the crack lines to help solidify everything

Hit the welds with the same flap wheel sander and things started looking up.

Mounted it - then put a bracket on. This time - I designed a thin bracket that will bend and morph if needed. Blindly tacked the welds and managed not to explode the tire. Done!

hey hey hey! back to tuning. the GSF dyno really captured exactly what I feel. Starting to pay more attention to that torque vs HP. Note its actually higher on the Polini. You can feel it!

Did you adjust the tire diameter in GSF dyno?

Christopher,
Missed your earlier comment - and Swiss's so all covered here: Unfortunately - all my prior GSF numbers had the tire circumference at 134 - while the real size was closer to 128.
That means they were all over-stated.
But of course - I am guessing at drag coefficient and other settings that are likely understated.
So the dyno results prior to today are probably reasonably accurate in absolute terms - and quite accurate in relative terms - relative being comparison between the changes.
Its a cluster.

So now the conundrum is: I have to alter all my old tests with 128cm input and re-run (not gonna happen) or I need to adjust something up in some manner.
For example - below are the same tests with the CD value at .6 rather than .5, and rolling coefficient at .06 instead of .03. Now it looks more like we should expect in absolute terms.

¯\_(ツ)_/¯ Go look at the dyno tests for all the motors on pipedesign.de if you want to get some relative reads on what reeds will add. It's pretty dramatic. A new drug? Swiss! That's like giving an alcoholic a gallon handle of Jack Daniels as a xmas gift. They gotta wonder - is this really my friend giving me this?

So what brand and what sized 11" tire did you decide to go with?

First - nice job on the exhaust (again)!

How about a mount like this type? I'm sure you could get it to work fairly easily. But don't want too much flex as it'll transfer any shock to the exhaust stub. A viton type flange would fix that though. They're known as bobbins/cotton reels etc etc



I think with the reed vs rotary in the PipeDesign dynos, you would probably find that the average size of carb on a reed engine is much bigger. That would probably account for more of the difference than the reed by itself.

Also, way to go spelling guy! A sentence with 'read' and 'reed'... a trap for young players.

Don't nock it.
🙂 Nice! Yes - this would do a good job and allow a bit of deflection at the mount rather than just ripping the top off the box. It's true there were a lot of larger carbs on the reeds. I would have to go back and see if there were any 28mm or smaller carbs shown. The HP on the many charts I looked at left me kinda gob smacked.

Box repair: best thing that happened to me all day. Put on Heidenau K80's with 110/70/11's before I went x country.
They are mounted on SIP 2.5/11 wheels.
This means no "wide tire" mods.

Had been running 100/80/10's and I liked them - but I was hoping for:
- a slightly taller tire now that I have added all this pulling power
- test what it was like to run less sidewall for tracking and grip with the sidecar effect

Also - while 11" sounds crazy tall - I realized that the 110/70/11's were actually slightly smaller than the 3.5x10's I used to run. (those were like marshmallows)
The new set up is firm - and can jolt a bit over rough rode - but man do they ride great in the corners and feel more stable on the highway. Net net - I like em.

No "nocking" here - I was impressed!

So is there much choice in the 11" tyre range? I went from 8's to 10's mainly because there was a choice of 1 brand (at the time).

Seems like all the usual suspects:
https://www.sip-scootershop.com/en/search/110/%E2%80%8B70-11?dim=2

I really liked the way it rode in the rally last weekend.
60 MPH hwy run all the way there and back - was almost fun.
In the corners and crowd when riding aggressively - two thumbs up.
But just puttering around - its harsher than my old worn 10's.

I softened the rear shock (which lead to the whole exhaust debacle) to offset it a bit. More adjustment available - and I might make use of that.

I think I am on 11's to stay.

Nice work on the comparison. No re-jetting between pipes? Welding getting much better btw.

Would be nice if this was compared to an expansion pipe? Daytona is a sound choice. Get it double walled and it will be even quieter. Once you've run a properly set up expansion, you'll never go back. It is addictive but not much else to get excited about these days.

Or you could just call it good, you know where your at now and optimized for your current setup. Moving forward you can still have a benchmark for relative comparison.

Nice to hear about the 11" tires and wheels, that's what I'd like to try when I wear this set out.

Last edited by Christopher_55934 on Wed, 18 Nov 2020 17:55:51 +0000; edited 1 time

Dang Chuck nice job on the Polini want to know about the 11" tires and wheels.

Thanks y'all.
Enjoyed showing off the welding.
Gotta get on some TIG next to get to full on pretty.
Maybe a little xmas gift - if I manage to clean up my garage sufficiently of all the crap that's built up in there. Since you are focused on making it more suited for some hwy cruise - I suspect you would like them.
The 70 sidewalls I chose are short - purposefully as I wanted to reduce any lateral flexing due to side car. Really worked well.
80's would be a bit taller than a set of 3.5x10's but add some smoothness if that was your priority - and would be just a hair taller than the 3.5x10s.

To my eye - the ones I have on look really nice - no different than anything from the 70's or 60's GS with 10" wheels on em. good eye. The SIP II might have been well suited to a bit leaner rod than the Polini - but the run is only measuring WOT and I did adjust the clicks to get it close. Ha! I am in discussions with Pipe Design for exactly what you describe.

Method to the madness. Thinking when all said and done - I may find a set of reed cases - that I could take my extra parts and put together a beastly motor. 32MM carb/reeds/bell/MHR/Pipe.
What exactly I would do with that motor is anyone's guess - but it would look shinny and cool on my stand waiting at the reddy to be dropped in - or perhaps it would find its way to being the daily driver...
Keeping these things from multiplying in your garage is tougher than avoiding teen pregnancies.

Circling back to the 11" wheels (see what I did there...? ), it's just a matter of picking up some suitable rims and tires to match, right? Nothing changes other than that?

I just want to be certain before I get all excited and start ordering stuff that might not fit.

Last edited by chandlerman on Sun, 29 Nov 2020 11:37:09 +0000; edited 1 time

CM1 - something happened to the URL's you posted so I can't see em.
But yes - no wide tire chopping half the swing arm off nonsense.
Just plug and play.
Think you could like em - and now you have to decide if you are going 70 or 80 series in height.
70 will be harsh if you have no adjustment to your shocks (or have your shocks set to max stiffness as I did! Ha!).

Here are the ones I bought:

Pro tip: you can get them to mount your favorite tires by adding "workmanship" 1 for each tire. See below.

I did not realize you could get them to mount any tire you wanted! That is good to know. I thought you were limited to only the ones they sell pre-mounted.. or tire and rim separate for your own assembly.

BTW, I am interested in this, but wondering what the benefit and reasoning is? Also whats the clearance on fenders and rear frame once you add these slightly larger tires?

Welp...other than going with K61's instead of K80's, I just pulled the trigger, so we can compare notes on the ride once they show up.

Swiss - I had two things in kind:
1. I wanted to decrease my side wall. My scoot with sidecar has more lateral forces than most. I thought it might be more controlled.
It is.
2. I liked the idea of a taller wheel AND tire for highway/ faster speeds.

My only comment to the gang is - 70s are harsher than 80s sidewalls.
So consider the trade offs between the two as 80s would make u a little taller but only slightly more than 3.5x10s.

As for clearances - it is certainly tight getting past the front mud guard - and rear changes mean shock bolt removal.

But I had that with the 3.5x10s as well so nothing new.

Really love these when I am driving it hard.

Let's see how CM1 feels about his after he has em on

I was wondering about having to remove the rear shock bolt. When I went to a longer rear wheel stud, it was interesting getting the tire back on. I figured when I went to a 2.5" rim, I would just pull it to save scratching up my wheel.

I have the 110/70-11 K61's mounted both on the front and rear of my Pink PK (stock 200/short 4th). I did try the HUUUUUge 120/70-11's, but they were just too tall of a tire for my stock cylinder to propel it up the hills in fourth gear. And yes to what Charlieman said about the 70 series tire being more harsh of a ride. Exact same concept of puting low profile tires on a car. The other downfall of using the super wide 110/70-11's, was that it's an overall heavier tire...which means that it has a higher rolling resistance...which means slower acceleration and a slower top speed). I wouldn't ever put these tires on a dedicated track scooter since it would make it slower, but for straight up bling, the 11"s are spot on. I'm glad i mounted them on my PK, but i wouldn't go mounting them on all my other scooters.

Did you get a 110 or 120 width, says a 120 would fit?