Modern Vespa

So Cal - first - big thank you for all the hand holding provided off line as I have worked to get my hands around this.

Second - see below answers. Chuckle - yes. The ports that let the fuel into the cylinder. Transfer ports = Inlet. The distance from the top of the transfer ports to the top of the cylinder, with a 1.5 mm base gasket in place, is 48.14. Using the calculator, if I plug 48.14 in, with a PBT of 1.95 I get 117. When I used the buzwangle, I measured 117 degrees as well. Ditto answer to 3 Correct.

Hey Socal, since you asked, I found five minutes to jump in here

The calc's all work, assuming a 57mm crank and 105mm conrod.

The results are what I'd be worried about.

On my Sprint, the timings are 124TD / 172 ED, and that's about the lowest I'd want to go, because I was looking for a wide power band with a long stroke and a Polini 177.

I'll have to catch up on this thread and see if I can help out more tomorrow afternoon.

Gotta run now, but good luck!

I replaced the M7 studs on my LML case with M8's, but for a different reason. The only difficulty you may find is that the 200 studs - M8's - are a bit too long. However I'm sure you can work around that, you just can't cut extra thread as the shaft is thinner than the threaded portion.
Doesn't matter if the current stud hole in the head is conical, just drill it.

I just measured one so you can see if this is an option for you... with the bottom screwed in until there is just no thread visible above the face of the case, it's 117mm until the top thread starts.

Actually the biggest hurdle I found was enlarging the hole in the thin base gasket. I angled a couple before getting it right.

Chandlerman! Thanks for weighing in!
More on that to come... Would welcome input on your experience.

As for the stud.
Yesterday I called a well known shop to order some 8MM studs.
Went something like this.

Me: hey - I need 4 8mm studs, but have a question before I order. Any reason you can think of that the current ones were turned down to fit 7MM nuts at the head? Will I run in to trouble just boring out the head 1mm larger to fit the 8s?

Guy: Dude - is it from Vietnam? BODGE!

Me: No, it's from Indo, and yeah - I get it - but any idea why they would have taken the time to turn down the studs for 7mm nuts? Seems like a nice way to add some strength with the 8MM studs. Kinda a clean job too.

Guy: Dude. BODGE! Them BODGES are BODGES. I have no idea why. BODGE!

Me: Yeah. got it. It's just that someone took the time to turn them down - just wondered why. Are there any other differences that might have caused them to opt for that?

Guy: BODGE word BODGE word BODGE BODGE BODGE ASIA BODGE.

Me: Well, ok - are the studs otherwise interchangeable?

Guy: BODGE BODGE burp BODGE.

Me: ok - let's order 4 of them with some nice flange nuts - I think I can do a nice repair with them if I can match what was done.

Guy: BODGE! use the internet and just order them there from us. BODGE!

Me: Will do. Thanks for your insights.

If the word bodge had been part of a drinking game - I would have been three sheets to the wind by the time the call ended. Ahh - and there it is. They have to be threaded down the shaft - where as you point out - they are narrower than 8mm threads - so they were cut at 7mm and used with stock head nuts from that model.

Ok - I am off to try and sort out how to repair case - threads are rough on this one hole - so planning a helicoil fix for the top portion and use of the threads in the bottom portion that are still good.

Some careful drilling in order.
Fire a quick post if there is something I need to know about helicoiling my case!


until then - BODGE!

And that was when it left indo... you should see how much more bodgey it is now!

I've seen a number of people say that Time-serts are much better than helicoils. Got helicoils in one case and it's not really as tight as I would have expected.

They're right...


It's initially a larger investment, but it's worth it to me after the first hole that needs to be fixed. I don't know how long since i quit using helicoils. I switched to Time-serts a long time ago. I keep a fair amount of lenghts and sizes in stock in my shop. As long as you have enough material around the hole for the oversized insert, they're the best thing ever. One place that i always install one is in the oil drain in the engine case. Everytime i split a case, i install a time-sert (whether is needs it or not) in there. No matter how ham fisted the idiot is behind the wrench, it will take great effort for me to strip the threads.

I do have time-serts in my lammy case for the cylinder head studs. There's no slop, it's a nice tight fit.

And that's being kind.

Gents - hats off to the crowd.
Killer input - total difference maker at every turn.
Helicoiled which worked well enough but have Time Cert on order in my size based on ya'lls input.
Bolted up and checked out how the cylinder decking turned out.

On to the numbers.
Took 1.75 off the cyl.
Had such a good laugh with the machinist I think he went overboard on nailing it. When I asked if I needed to lap it, he just looked at me like - you are not going to make it better.

1.5 + .2 base packers = 1.70
Exhaust Port 119.00 Buzwangle 46.11 measured
"Tansfer Ports" (So Cal - that's for you) 173.6 Buzwangle. 34.35 measured
PBT .20 (avg of three measures)
Squish: .96

Tomorrow will turn down one of the 8MM bolts for 7mm nut to match others.
(Do I need a 24/24 carb? )

One interesting thing that showed itself through the discussions:

SoCal likes the set up he has with lower port timings. Rugged and grunty with reasonably dangerous top speed for tube tired 8"ers.

Jack likes the sparkle of 118 min for my set up - and I used his targets which seem well founded - we are there.

Chandlerman set his up with 124/172- and doesn't think it should be any lower (maybe higher?) Wanna here more pls.

Suspect everyone is right - and that other variables come in to play. Not exactly the crowd to sit still if disappointed...

One thing I plan to do: throw a 1mm head gasket in after break in and compare to see how important the tight squish is in my set up.

Once I can safely take the head on and off without loosening up the studs that is...

Cylinder studs are a real issue. Helicoils are the first thing to try. Especially the green German Bullhoff ones. Timeserts are what is used when its all gone wrong. Once a timesert is in, the hole is so big, there is no other option.
Personally I never take the cylinder studs out, ever. Never ever never. Swing the engine to slip the cylinder off (faster). I use sleeve nuts on all 4 at the head. With the longer thread they never strip or wear out.

Yay, cylinder is cut. With a real measurement of 46.11 from deck to the main transfer and PBT of 0.5mm, then you have 120/174/27. I suggested before 118 as a minimum, so you're there. Going to go ok. Without the side car more duration would be better but this will do for now.

Another option ... M7/M8 repair stud:

http://scooter-speed.com/vespa-cylinder-stud-repair-sip-m7-m8x140mm-8005-15065900/

Nice find!

That looks to be what was in my case.
Guess it's a thing.
Makes sense.
Perhaps I will forward to the other part's supplier.

Trigger warning. You will not be able to un-see this once read.

Bought some of the 8mm/7mm studs locally (appear to be a SIP product) and got back to assembly.

I assembled, torqued to 10 lbs, and pressure tested - where upon I heard a hissing coming from under the flywheel. Pulled said flywheel and stator to inspect. Significant streams of air could be felt on my face as I got close to the leak - the motor would not hold air.

Bad flywheel side crank seal - or was it?
On closer inspection, I could see bubbling at the seam between the seal and the case. The seal itself seemed fine.

To replace, I will need to split cases - which I have resisted for a handful of reasons.
1. Who knows what kind of stripped or ugly things I will find that will need proper addressing.
2. When I split, I will replace crank (60mm), change gearing, new kick start gear and pads, bearings, seals, inlet timing... So I want to do a nice job of it when time comes.

However - I don't want to get in to that all until I run it a little with the new cylinder to see how I like/what I learn - i.e. determine what my gearing should be.

What to do, what to do.

And then it came to me... (best viewed with hand over eyes, peaking through fingers to avoid being blinded).

I'm getting skeptical of what's the inside of your case might look like now. P200 cases are getting harder to come by, but used Stella cases pop up. They would also be a great building block to get more torque for pulling a side car...especially uphill. I'd just be hesitant to put any money into your existing case (such as transmission, crank, bearings, ect.. when all those same parts would cost roughly the same price as the internals for the Stella. I always like to start a build on a know solid foundation (as in engine block). At this point, you could transfer your cylinder kit and clutch over to a Stella engine block.

Doesn't look like it was peened at least... and that's a good sign. It's allowed to be old and worn.

And as a bonus, fiberglass motors are very light!

I've ear-marked my VBB motor for Brother E, otherwise I'd try get that to you. I have no idea how I will get it to Brother E at this stage tho. Hopefully Bali.

But... I do have another VBB motor in bits. If you need anything (cases...) then I'll show you the condition of the pieces and work out if useable.

How does your leak detection system work? Is it easy to seal the carburetor and exhaust?

WDC! Thanks for that.
I knew there would be some howls when I showed off my new sealing technique... couldn't help myself - was chuckling as I posted it knowing the tomatoes and beer bottles would start flying.
In truth, it'l probably last longer then the actual seals themselves.
It came out pretty damn tough/rugged - only took 15 minutes to do.

TBH - I am not so scared of the current motor/case.
The 8mm studs were a solid solution I would have executed myself.
The fly side seal - well - the cases are not young - it's true.
But there was non sign of bodgery there - just a bit worn.

However - your point on a more robust set of cases/ or p200 advantages all makes sense. But in the mean time - gonna make the most of what I have. Thanks brother. See above - agreed - cases are a little worn - but I have a good machinist lined up now - and my sense is - the cases are really not in that bad a shape.
Save that shipping money for a round of beers should we find ourselves in the same hemisphere.

Hibert - I had the carb off. I used a piece of aluminum plate cut to cover the carb hole - with a piece of rubber pinched between it and the case. There was a very slow leak there - I could probably do a little better job but it got the job done for me generally.
I used a rubber plug shoved in to the exhaust stub to seal that off.

The leak down tester was from harbour frieght - and I wouldn't recommend. It goes to 100PSI - I only needed 5-7lbs so the gauge is totally the wrong scale. It helped me find the leak - and the engine is frankly tighter then ever now that I made my custom patch - but there are other solid low cost leak down tester's that make more sense.

Just in time to make date night - I rolled it out of my garage and shot this:
Not bad - given the carb was completely empty of gas.

All things considered

Tough crowd...

I'd say that's a cause for celebration! With a beer or something...

I don't have an issue with the hondabond fix. Leaky seals probably kill more Vespa motors than anything, if you're talking Root Cause. I use Loctite 603 on all my seals, but that requires you do it at the time of install.

I do stuff all the time that would send Purists to their fainting couches. For me, it's about pragmatic fixes and improvements. So long as it works for you, screw those guys!

Thanks gents!
So nice to be back on the road today.

Heroin.

Need some milk? I can make a run. No problem honey.

What's that? Dog needs kibbles? I got it.

Meet for lunch few towns over? Great!


Bike runs great.
188 temp was commonly seen.
Had a few 30 - 45 min runs.
Had to work to get to 225.
Shifting around 5500 and using about 1/4 throttle most of the time - cause it runs so willingly up the revs getting there.
Torquey. Fun.

I'm probably one or two steps rich - nice way to break it in.
128/BE3/160AC.
Keep in mind my fly seal leak was operating as an auxilery air injector previously with same jetting. Sealed tightly now with my composite patch. Getin' a lil extra pleasure outa that one every time I twist the throttle.


Will optimize this jetting - then perhaps experiment with a BE4 stack of some kind - I suspect jack has in store for me.

Sounds like you're all over it Charlieman, well done. I knew there was a reason I like you.

I had all sorts of advice when I started in this obsession, including "if you use anything at all on gaskets, use grease. That's how they were done originally". Never really understood that... the naural progression from that is only use grease used by the factory and only the particular colour they used.

Maybe this had something to do with needing to run with the carb box lid off?

I second that. Sealing the seal with Hondabond was an ingenious and ez fix.

Considering six months ago charlieman here had never even laid eyes on a Vespa engine I'd say he's done a pretty remarkable job.

Looking forward to seeing how the porting works out once the top end has been run in... which, with all the grocery runs, should be sometime tomorrow afternoon.

I second this! I am amazed by what CM, the spongeman, has soaked up and makes happen. It is very fun to follow along, well, really more like trying to keep up.

Plus, I don't get upset by little thing like setting my scooters on fire... Yeah, for me, I view what I do as "renovation" rather than restoration--it's about bringing the fun & style of vintage scooters into the modern world. It's all well and good if people want to do concourse restorations or run points ignition and 6V lighting, but that's not for me. Automotive technology has come a long way since the 1960's, and I see nothing wrong with taking advantage of those improvements.

I'd rather bring as much modern tech as a two-stroke geared scooter will allow. More power, better performance, modern features in a vintage package. To the inexperienced eye, they look totally vintage other than the LED lights and maybe the sound of the motor, if they even know what it "should" sound like.

Yeah generally agree. At the end of the day there's only a handful of these old, slow scoots I'd actually consider as candidates for a full blown nuts and bolts restoration. I admire museum quality work, but for me, it's about having fun with what you got. My only rules are respect the design, try not to make irreversible changes, and don't forget the cotter pin.

The other problem with museum-quality work is that you wind up with something that's too beautiful to actually use. I'm a big believer in having bikes that I won't get upset if something happens to them, i.e. my fleet of "Shifty Rats."

Or, to quote my dear, departed dad, "If you ride it like you can't stand the idea that something might happen to it, just shrink wrap it and leave it in the garage."

Shifty rats FTW!

I got left behind when the numbers and TLAs started occupying every other word space.

But still got some popcorn left...

Actually made me laugh out loud... love it.

One of my first posts got a response that was taken down by the moderator for breaking rule 1-3: don't be a dick.
I happened to see it before it was removed.

The gist: "GTS - Google that shit you moron. Type "Site:Modernvespa.com topic" and read the results"
So I typed it using "disk brake conversion" or what ever I was trying to get info on.

Google produced every post in chronological order of all disc brake conversions that are on modernvespa. I was kinda knocked out. (hey - I'm getting old and this shit is getting tougher to keep up with).

This time - the "composite bandaid" post returned me (along with a hand full of laughs from you guys) the loctite to seal bearings insight. That's a gem.
Like the search term feature - you guys might know it as normal - but it was totally new to me.

Up next - the piston ring design concept to allow full bore diameter cutting of the exhaust port... who wants to be limited to 65% when you can go 100%? Can't wait for the feedback on that one - am sure some of you guys must be experimenting in this area.

I swear - since joining this forum - everything I see around the house looks repairable to me with a dremel, some JB Weld and occasionally a little fiberglass.

Craig - I suspect your on to something.
When the carb has flow resistance (like when bellows are on) the case sucked air through the seal.
So no matter how rich I make it to compensate for the extra air - the volume of gas air mix was lower (and I could not get the performance out of it).
By removing bellows and box top - the carb flowed freely. By going richer now - I could get the right mix, but also keep my volume up = more power.
Guessing - but that makes sense to me.
Will experiment with adding back the bellows and carb box top - would love to have them back


BTW - your tireless efforts and documentation on air leaking testing & discovery were a great primer. Tks!

Not us guys, but this guy... https://youtu.be/JGK-Sa89Pmk
If you haven't seen him before, he's great. Recently he cast his own cylinder, and is going to use the piston discussed in the video in it. With an exhaust port at 100% of bore... He's dropped that for the moment as he is shortly to run a 50cc "motorcycle" (self built apart from cylinder) at Bonneville.

I have seen him before.
Agreed - he is great.
He is frequently sipping a cup of coffee or late night with something brown in a highball.
Creative as hell - with Finish stoicism.
Fun to watch.

Due to happenstance - right when you and Jack gave differing opinions on how wide I could make my exhaust port without eating rings - I saw his video, and it just clicked.
I figured maybe others had experimented with this (I am not sure I registered how recent his postings were).

Best I could tell from his video on the piston, he really doesn't show how it works - or if he did it was over my head.
The screw top piston seemed complicated - perhaps that is for other purposes.
He mentions its a "retained ring" though - so you can imagine how it keeps it from falling in the wide open port. I am sure there is a lot of finessing still needed (half the piston wall is gone after all).

I have an idea about how to execute in a fairly simple manner.
Also thought about how you might manage dealing with piston tilt as it goes past the large mouth bass exhaust port.
I have no idea if any of it will work.
Thought it would be fun to try with my extra Polini piston - just to see if it functioned on the bench.

For those of you who haven't seen this guy - check him out - good entertainment value as well. Perhaps the Piston experimentation should be it's own thread.

that was a fun video I liked the end when it shows light in the exhaust port.

Maybe the screw top piston has a double dykes ring or something that can't go beyond the inner retainer like a u

Seems like the side car is going well. Nothing wrong with bodging the bodge, you can sort it all when there is no choice but to split. How that driveshaft is holding out I don't know.

If you are still running with the box lid off, then this jetting you have is not for you. Much higher power kits run perfectly with the box top and bellows on.

Remember half of what the Norwegian guy says is only about small bore (50cc) engines . I wonder how fast a 50 Special could go with some of these ideas?

That's not the piston he's going to use, he's got one made by this guy. Note how much lighter the piston is than a standard one - about 2/3! Which surprised me as it looks heavier. However if you watch the second video you'll see it has the trapped ring - which he described as a "reverse Dykes" (L shaped).

https://www.youtube.com/watch?v=YEaE6BHyjzg
Of course he is unhampered by stud location or case design, since his case is milled out of 2 blocks of aluminium and with no gearbox to worry about. I'm not sure what class he'll be in but the unlimited class seems to have a record of 144mph.
Certainly the pistons that Mark Atkinson shows in the video above are a good deal bigger than 50cc.

50 Special has no studs. Port could be a wide as the metal will take it. Doubt it will make 144 but 70mph could be a target.

Mark Atkinson does racing twins. Mostly 400 and 100bhp+ Some of this technology works for us too!

Ah yes of course, the 100 Sport motor Voodoo sent over had the short studs that hold the cylinder down. It seems like a good idea, nice to see one of the manufacturers use that system to make something a bit more adventurous for a largeframe.

Got it.
So that's pretty cool.
Maybe he can make pistons for vespas...
But knowing how this crowd likes to do it themselves - here is a less complicated concept to stop what he calls "cross over" and add retained piston ring to a std Vespa piston we all have.

Trick I saw on the highest reving Datsun motors As a teen - Was to use floating wrist pins (normally pressed in) with teflon "buttons" in the end to keep the pin centered. While that was for different reasons - it is a cheap and simple means to plug the through hole.

A pin pressed from under the piston once the retaining style ring was put on could retain (ring would need hole and extended "L" portion. )

In this case - our standard pistons could remove cross over, and have retained size.

Thoughts?
How big a deal is "cross over" ?