Modern Vespa

Oh, yes. K58's. I wasn't that impressed with them as a rain tire. I had a few pucker moments with them (when compared to a Conti Zippy)...

- I had a front wheel drift going about 35mph on a wet cloverleaf highway offramp.

-I used the K58's on the racetrack on a rainy day. I had HUGE front and back wheel drift with them. SO much so that I pulled out of the race two laps in. It was like I was on ice. No one else seemed to have problems with their tires that day. I had much better luck with their super gummy "rain/race" K58 version, but that tire wears out super fast.

I was thinking the same thing...who cares about a loud tire on a two stroke?...until I installed them and got a reality check. It also made the scooter vibrate enough that I though something happened to my crank. I was happy when those tires finally wore out. Others might not have the same issues with the K58's. I tend to push the limits a little more of my tires, and I expect them to perform as they're advertised.

Gracious - good to have you guys pontificate a little around the issues. Lemme recap it here - love the input.

Frist - general spec:
Tires:
Going tubeless for safety.
1. 3.5-10 Conti WW K62 (fairly flat profile) for rigid sidecar set up
2. 100/80 - 10 Heidenau K80's for leaner sidecar set up.
The idea being - sportier cross section profile will be more appropriate to leaner - and flatter profile will perform better with non leaner set up.
I'll have two very different types of tire to test with.

Exhaust:
- SIP road II

Inlet:
- Polini venturi. Will C how I like this as a stand alone and then with exhaust to see what effects I get separate and in conjunction.

Cyl:
Polini 177

*new motor mounts mean engine will need to drop - still no plan to split.

WDC: Got it - thanks - and have already experienced similar myself. compound and tread pattern can be felt

Jack: Virtually... we will find out. Like the thinking here - matches what I heard on the street. Wider squarer exhaust port = max out power while maintaining torque. Logic I heard. GS rings are solid wire. Std. Polini are cast. Significant strength difference - especially over long span like squared up exhaust port.
Still may choose to just chamfer ports and bolt on as is out of box.
Happy to map and take measures.
Swap a base or head gasket.
Wanna learn.

Question to the expert tuners:
What would be the set of specifics you would recommend for optimizing the porting for torque?
Do you need to see std specs first - lemme know - I'll post?
What spare gaskets - if any - should I have around for the install?

Jack and Swiss: Getting gearing right holds some value here.
I don't know my ratios - unfortunately.
First and 4th feel a hair tall.
2nd &3rd less so.

I've not really dug in on clutch very far - but like the idea of a PNP strong clutch - that doesn't cause carpel tunnel - and has a one less toothed gear on it.

I've read enough to make me dangerous regarding set of specs.
Heavier basket
Number of springs
Honda discs
Smaller drive gear
But haven't done full homework on this one yet.
If it is truly plug and play - perhaps should be higher up on my list.

Assume I will have to disassemble to get info on gear ratios, clutch teeth,etc?

First batch of stuff - wheels/tires/venturi/exhaust/ swing arm mounts - arrive t'day.

Thanks for weighing in ya'll!

I'm not going to try to impact your decisions at all.

3 simple questions.

How many miles have you done so far on the bike?

How many do you plan to do on a 2 stroke motor?

How many of them do you want to spend running in a cylinder kit?

Gt6 - valid point.
Appreciated.
Boxes delivered to porch last night.
Sip Road II/Venturi/Tubeless & rims.
Project advancing nicely for me on the "certainties".
Parts will go on bike this week.
Cyl - not ordered yet.
Will c how much exhaust extends range of drivability.

Managed a few hundred miles + since acquisition.
So run in is considerably longer than a few weeks...
(tho bike was not really serviceable when first brought home).

That said - I suspect I'm in the two stroke business for long haul.
Just can't see giving up the gears/riding experience.
Install of cyl. sooner or later is in the plan.
Soft plan also imagines second scoot... what can I say.

One elec - one 2 stroke?
One leaner - one fixed?
The fixed is it's own fun to drive.
You have to stay on top of it and work it - see below.

Still suspect smaller gear on new clutch might have quickest bang for buck.
Speaking of which...

Would welcome some help from crowd spec'ing a clutch and cog that would:
- Be reliable/strong/but reasonable actuation effort
- Have slightly smaller gear than stock

Assume I am at 22 teeth - I understand that's stock.
Would need to drop to a 20 if I am understanding correctly.
Which basket, what plates, etc. not as clear.

Solid choices, cman. All the homework you're doing is going to pay off.

Unless you're in a huge rush to get everything done at once (rhetorical proposition since we all know tinkering is never "done") I'm going to suggest you take the One Change At A Time approach to this. Do it in the name of science. Let's see how things work PNP before making any irreversible changes... actually see whether and how much of a difference new part A makes before grinding or modifying it or trying it with new parts B, C and D. You aren't going to be making enough power to be worrying about exploding clutches. A 7 spring should be plenty. If you want smoother, easier puller I'd go BGM Super Strong - pricey and overkill, but a sweet upgrade. While you have the engine dropped for the mounts, pull the clutch and see how many teeth you have on the cog now. Pretty sure you aren't going to want more teeth.

This is gonna be fun.

SCG - Thanks!
Pipe goes on this week.
Probably the venturi as well...

Was surprised to find so many running at least one bike with venturi.
Believe Patrick/OKT recommended leaving idle alone when adding venturi.

Curious about what you guys think.
Current plan:
- Up main 3-5 points for box exhaust.
- Up main another ~10 for venturi

Seem reasonable?
Also - insights on idle jet - do I leave alone?

Wadda ya'll think?

Been through a few clutches. Figured I go easy on them, shouldn't need anything special. Had I bought the Superstrong at the beginning, I would have A. Known much less about clutches B. Spent less on clutches C. Spent less on tow trucks. I love that the design does away with rivets etc, making the wearing surfaces much more robust.

How much extra load is a sidecar going to transmit to your clutch? And considering what you've spent so far, it doesn't seem like overkill in any way.

Yep, Superstrong with CR80 plates; clutch done.

The easiest way for you and Swiss to get the main jet ballpark is,

With a hot engine running on the stand, hold it wide open on the stop until max rpm, keep it there for a bit, ignore the neighbours.
Spluttering, not getting 8000+ rpm (or rpm about 1000 more than you could ever get in gear) and garage full of smoke is too rich.
Revs like a race bike and makes you scared you will break something expensive is running too weak.
Revs right out clean to 8000+ and possibly with very light splutter is good to go.
From here you can fine tune on the road.

Worth checking the plug when doing this?

Ha yeah good advice and ive definitely done that enough to my neighbors. Now i throw my tools and jet kit in the glove box, ride the scooter down a few miles to a parking lot along the water looking out at Manhattan where no one will care if I'm noisy, then throw it on stand and rev it out like you said and mess with carb. It's far enough away that the scooter is warmed up by the time i get there, and i won't be pissing neighbors off, just random homeless people hanging out on the rocks along the water!

Careful parking near the water. If she jumps into gear while revving high it will be like the start of Quadrophenia all over again.

PP takes many miles wide open to get enough colour to check

Lol. that's why I park facing the street when doing that!

Read clutch advice.
Just about to respond.
Commend/thank the crowd for sage input.
Just my luck - would be during a rally - rivets fail.
Just before hitting respond
Read Jack's jetting tips for Swiss & I.

Hahahahaha. Belly laugh.
One thing for certain - you can count on effective if reckless advise to be dispensed here. No extra charge.

Don't think these guys crossed the pond - but it seams you have solid company.
Tks!

and remember to bring ear plugs for two reasons. #1, it will save your hearing. #2, you won't think your scooter is loud as it actually is, that way you won't feel as bad when you're rousting the homeless.

I'm already hard of hearing from years of playing the drums with no protection!

I did think you were taking the piss. But then I'm like... maybe I'm missing something and calling him on it will be offensive. And I don't know wtf 4 stroking is. Maybe I'll just see where this one goes on its own...

"Supposedly Cousteau and his cronies invented the idea of putting walkie-talkies into the helmet. But we made ours with a special rabbit ear on the top so we could pipe in some music."

I even had a Team Zissou Vostok... but ironically let water in the first time I surfed with it on. Kinda too small anyway.

want!...
http://kelticsidecars.com/

My neighbors already refer to me as "that guy".

Exactly.

So my primary is 67 (4 counts - 4 times 76...) and my current clutch is 22.
Thinking the smart play would be the 20 tooth BGM superstrong CNC CR80.

Appears to be for a 67 tooth primary.

1. Is this the right part?
2. What do you guys make of the 67 tooth primary - did the builders grab a non stock primary to gear it down already - or was a 67 tooth primary stock?

Thanks!

https://www.scooter-center.com/en/bgm8296/clutch-bgm-pro-superstrong-cnc-cr80-type-cosa2/fl-for-primary-gear-67/68-tooth-vespa-px80-px125-px150-t5-125cc-cosa-sprint150-rally180-gt125/gtr125-ts125-gl150-super125-vnc1-11001-super150?number=BGM8296

Edit - appears that both the 21 & 20 tooth version run with the 67 tooth primary - so also need to choose which...

Well done getting the clutch out.

For next time you can remember where the notch is and set it so the key is at the top. Cosa clutches are easier.

Be sure to do the clutch nut up extremely tight. Loose clutch is the quickest way to destroy a crankshaft.

20 teeth is too low. 21 most likely but 22 might work too.
Once kitted and jetted there will be more torque (hopefully). I'm thinking 21.
Have a look about for the Superstrong Cosa clutch. MMW make one too.

Thanks Jack.
The fishing of the woodruf key out blindly from the gear box was some kind of crazy diving save - I assumed I had just learned a tough lesson when I felt a little click through the magnetic stick and pulled it up. The words - "No f*king way" just rolled off my tongue.

Pheas' - consider the magnet on a stick my new favorite tool.

Question: are the Super strong clutch models you are referring to different than the BMG link I posted - thought that was the one (though that has 20 teeth).

Plan - re-assemble with current - now I know its 22.
Put pipe on and venturi.
Jet - and see if I feel like a little smaller cog would serve my riding needs well.

It's rare the key actually falls into the gearbox, so lucky it went in and amazing it came out.

This the MMW. Not seen a complete CR80 version but would cost way more than the BGM.
https://www.sip-scootershop.com/en/products/clutch+basket+mmw+superstrong_93247000

and another cheaper choice (but riveted)
https://www.sip-scootershop.com/en/products/clutch+sip+cosa+2+race+for_93403200

Then again, is Ultra better than Super?
https://www.sip-scootershop.com/en/products/clutch+sip+cosa+2+ultrastr_93403300

The BGM complete comes with CR80 plates, so like going with women shopping, back to the first one you saw.

Nice job!

I kept telling myself gravity was on my side - musta hit the primary and spit forward - until I had to give in and get out the magnet... Lesson learned on rotating so key is facing upward. Indeed. Good chuckle.

Does anyone know what the stock gears in my bike are for the counter shaft and drive shaft? 1962VBB.

Ginch posted this elsewhere - very helpful - but not sure I have right existing numbers plugged...

http://gearingcalc.free.fr/

Yes if you search for gears for your model, SIP has a page with everything listed. Maybe in the pdf on the right hand side. It tells you what meshes with what, including non-stock options. There's another one for clutches...DRT make a bunch of clutch gears that fall between the Piaggio ones.

Glad you found the gear calculator useful...the visual output works much better for me.

Pretty sure VBB gearing is the same as Super.

Primary: 22/67
Input: 13, 17, 22, 27
Output: 57, 52, 48, 42

But remember VBB's came from the factory on 8" wheels. The 10's on there now effectively upgear it.

I'd personally go 21 on the clutch. The closer ratios make for a quicker bike. Maybe hold off on a new clutch for now ... stick the 22 back on and see how it goes with the kit .. you can always swap cogs later if you want more pep.

ps way to nab that woodruff

Ginch/SoCal - Thanks.

- I plan to assemble with existing 22teeth and drive.
- Both sets of wheels and tires have arrived. Conti 3.510 are as tall as bike wheels - nothing like the 3.5-10 I already own. Had to double check they weren't 11's. The 100/80 - 10s are as calculated/expected.

Not sure what to make of it. Point being - not just 10" wheels, the size of tire has enormous effect on circumference. For interest sake - will post some pics and measures.

- RE gearing - been through SIP online and catalog pics - struggled to figure it out. They list VBB 1st gear. no 2-4. Don't list VBB under counter shaft at all best I can tell. Perhaps I have the wrong section?

The build it and drive it and then determine clutch size - is solid advice and the track I am on. Pipe and new motor mounts go on this weekend. Perhaps venturi if I get lots of riding time in. Have three very different height tire set ups to run with - should be interesting.

Headed back to LA.
Wife texted me this pic this afternoon with no qualifying verbiage.

[/img]

So - I was replacing my motor mounts.
Next thing I knew - I had the motor on the bench with the cylinder off.
You know - while I was right there and all...

Thanks a truck load to SoCal for bailing me out with some timely and insightful handholding. Life saver. Thanks!

Found a little crazy SEA stuff - that is to be expected.
Good - case is ported for third port - and nicely.
Weird - Big squish and a head gasket sealed on with some form of high temp sealer.

Ok gents - let's hear some opinions.

- Base packer .55mm
- Base metal gasket .25mm
- Piaggio D cyl and piston (assume it is a few sizes over) - no scars - nice shape - both look new (which matches build sheet I got with it)
- .87MM - 1mm head gasket (also - not a typo) - could be as much as 1mm
- .9mm - 1.1mm TDC to top of cyl.
- Head + gasket = 2.8 - 3.2

- Squish measured with solder = 3.7-3.9

I assume I am getting a little compression from head gasket and packer when I torque head down - and measure with solder - thus the difference.

Do I:
- Remove the packer
- Remove the head gasket
- Do both
- Do neither - reassemble - hey - its been running really well - and order that three port polini
- Other?

Anyone have an opinion?

Now thats big. Raising a stock cylinder means someone knew what they were doing but with that kind of big squish and the jetting you had, then maybe not quite so much. See all those detonation marks on the head. The old piston was probably a total mess.

As the head is off, you know someone who can skim that head flat? You'll get a new one with the Polini and unless you're into antiques, it's garbage anyway.

If the head is skimmed flat, the cylinder can be packed up until 1.1mm squish. This will give slightly more torque. Taking the packer out will make it go worse, making it bigger will go better.

Jack,
Interesting take.
Question:
Why not just scrape the head gasket off. Would make squish about 2.5 ish. , down from 3.5 ish.
Leave packer and gasket at base as is (.75 total cyl lift).

Wouldn't this take me in the right direction without machining ?

With 2.5 all you would notice is it starts easier. If you know someone with a lathe or a
surface grinder it won't take long. While it's off.

Thanks!
Got it.
The gasket is tough to be certain of thickness - but few re-measure's this morning have me convinced it's 1mm.
Using measured Squish - that would in fact take me down to 2.5 ~ 2.6 MM range.

Taking that you like the .75 lift of cal (.5 +.25 packer and gasket) for torque.
What would my target range of squish be - low and high end - if I were to mill.

Would piece of glass and some sand paper not get me there fairly quickly also?
Much appreciated.

-CM

Looks like you kind of back-stepped into a little o-tuning. Hey, why not?

Scratching my head trying to figure out what the point of the 1mm head gasket is/was. I'd scrape it off along with all the goo holding it on.

It's probably a waste of time/money sending the head off just to get machined flat. Stock heads don't really have a proper squish band anyway. When you buy a kit, it'll come with a better profiled head. For now just get rid of that head gasket, and use glass and sandpaper (or valve grinding paste) to get a nice flat mating surface. If you can get a .5mm off, great. It'll take a lot of lapping.

Does it look like any work has been done to the cylinder ports? If not, I'd take out the .25 base gasket, and just leave the .50mm, but I don't think you'll notice much difference either way.

Given new cyl in near future - strip and lap of head is preferred approach. Excuse to listen to music and have a beer while doing brainless work.
Thanks!

But now I've gotta ask the crowd - cause the alchemy/dark science thing is hard to rally behind - like to know what I am trying to achieve!

Question:
- What is affect on torque and power band in general from raising cyl? Do I want to go up or down?
- Relative to port shape and height - What might I do to try and optimize a high torque mid range power band for my application?
- What Squish am I trying to achieve for my desired power band?

I will be right back here with the Polini in not so distant future I suspect.
Help a brother to fish so I quit steeling your french fries! (Chips, not crisps).

Thanks guys.
- CM

I replied yesterday but must have forgotten to hit submit! I was very eloquent and succinct... oh well there's always next year...

Mike is absolutely right. That ashtray has no squish band... no matter how much you machine it you will not get anything meaningful. A real squish band directs the gasses to the combustion chamber proper at the right velocity, and inhibits detonation by being too small an area/gap...

Ginch - SoCal - Jack,
Thanks. Very helpful.

I can see what you mean about the squish band - stock head seams to have more of a beach entry pool at the shallow end then a wrap around squish band.

I determined that I am going to put it back together like it was - add the Road II and see how that one component behaves on its own.
What ever the builder did back in Indo - they had some specific ideas - and its run nicely.
Then for fun - and to feel the difference - pull the head and take the gasket off/ perhaps mill it down - just to learn how it was affected.

But I am not sure how much squish actually exists in a stock head - based on that small flat shallow section on single side.
New cyl I assume will have something more impressive on that front.
So may skip that step.

Sooooo.
Head back on - installing BGM super strong clutch.
Ground away some of the obvious interference points on case and clutch cover - then dry fit. Was just taking some beauty shots of my dremel work - you guys know I like to dremel - and realized I had an issue.

Significant interference between clutch and cover - not even close to fitting.
Went to internets - FMP has his grinder out doing full on ice sculpture work on the inner cover to fit the clutch rather than the nip and tuck work I had done on mine.

Oh boy - here we go...

However - he provides some measures of covers and says there are 25 or so different ones - and mine is significantly larger then the one he had to grind.

So I took a closer look. I have two washers - not shown in his video - on my crank shaft. They shim the clutch outwardly. Perhaps these were put there for the clutch that was used - but not required?

If I remove them - clutch seams to seat nicely on raised crank shaft journal - and fit under clutch cover.

- Do I need to get out the grinder and go wild on the clutch cover?
- Or were these shims added and not required for the BGM install?

Thanks!

*Edit - see from exploded views that there should be 1 - not 2 - washers in place. Question though remains - do people remove this entirely to create clearance - or is it mission critical? Assuming it is - does the taper face out or in towards engine? (see pic)

I'm see while I was changing country they talked you out of it.

Those offset heads are, let's say not good. Agreed.
Dropping the cylinder any will reduce torque and it will be worse.
My fear was mostly for the compression. Essential for torque.

Didn't mean for you to spend money on that old doorstop. Just meant get someone to do it for a beer. Half mm on glass takes all day.

Here's the quick pre Polini suggestion. Clean off the head gasket. Put another 0.5mm base gasket on to make 1.25mm. reassemble. Ride. Maybe up jet one size.

Superstrong. Grinding out the cover takes forever. Not gone through one yet but it feels like it could. As the plates wear it will grow so needs clearance too.