Modern Vespa

New here, from Portugal!

Starting this thread to show the progress of rebuilding my LML Star 125 2T Rotary, that I bought last year as my first scooter. I have some experience with offroad and street bikes, zero with engine tuning.

The chassis and engine are stripped and now I'm collecting the parts I need to rebuild the engine. I'd like to reach around 22-25hp:

- New bearings, seals, gaskets and Clauss Studios full mount kit
- VMC Stelvio 177 with Meteor piston, lateral side plug cast head
- Long stroke crankshaft MAZZUCCHELLI K2D
- 1,5mm shims for the head to run 60mm stroke
- Carburettor DELL'ORTO/SPACO by SIP SI 24.24E with throttle slide SIP 4.0
- Transmission 23/65??
- Sip ultrastrong clutch??
- Polinibox exhaust??

Anything I'm missing or should reconsider?



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Welcome!

First off, 20+ HP is not plug n' play territory. And doing it on a rotary, even a 187, is a pretty good trick that most people never achieve. 15-18 is a much more realistic goal, especially for a first build.

Now that I've gotten that out of the way, the first thing I'll say is that you're probably going to need a tuned pipe or a big box exhaust like a megadella.

Also, let's talk about some more specific goals. Are you looking for a highway tourer? A stoplight racer? Do you need a wide power band or is something peaky ok? What sort of top speed are you needing?

And, of course, how frequently are you willing to rebuild the motor? Because highly tuned motors need about 10-15x the maintenance of a stock-ish build.

Next, you need to add aluminum to the cases so you can open up the transfers, then get to work on the cylinder and piston with a Dremel. You'll also need to open up the intake, both length and width. The exact timings of the intake, transfers, and exhaust are a bit of math, more than I have time or information for here.

If you're trying to get that much power, a reed valve intake from MRP or similar would most likely make it easier.

Oi tudo bem? Hope this is a shopping list and not an inventory.

The stelvio 177 doesn't have 20bhp in it (even tuned). Other kits that have are available. When we know what performance is expected, advice can be focused.

I'ts hard to answer those questions without any scooter experience. I bought it mainly to commute with low fuel consumption, to spare my car that is high on petrol (~12L/100km). Let's say I will use it for commute and occasional B road. I guess a wide power band is always a plus and 70MPH seems plenty to me. I have a Hornet to reach higher speeds.

What rebuilding intervals are we looking here? It will see 2.500-3000km/year and I wouldn't like to rebuild it in the next 20.000km.

The last part is what scares me the most, adding alluminium to the cases is clearly more that I can chew, unless there are clear instructions somewhere. I would like to keep it rotary.

Thanks for your feedback.

A few pics








Cases wire brushed. Too bad I don't have vapour blasting near.
Waiting for Clauss mounts now to proceed.

Welcome to the forum. Contact username: PSMA. He is from the Azores and he rides with a few fellow scooter vespa riders.

As per your goals, 25hp ain't going to happen. The 166-185 cc kits gives you around 15 hp. you will have to do very extensive work to achieve 25hp and not to mention the amount of money involved.

I just did a cheap Malossi 177cc iron cylinder kit on an incredible price range, I paid $249 and that is a steal!!! the amount of performance that I got is worth every penny. The cylinder kit allowed me to hit a bit over 65 mph(up nearly 15 mph). I added SIP road 3 exhaust box and although I did not improved on top speed I did improved the acceleration dramatically.

I'll be honest, not many people ride on a LML kitted at 70 mph(GPS), 99% of the kitted 125-150cc can't reach a 70mph GPS, most will do between 63-68 mph (GPS). I just don't want you to set a unrealistic goal, my speedometer hits 75 mph on the 2005 Vespa PX150, my GPS says no way Jose, I am doing 10 mph less than what the speedometer says.

Get yourself a mid entry cylinder kit(Malossi , Polini) and do an exhaust box and don't look back. You leave in an island and you probably want to have the midrange torque of the exhaust boxes.

As far is the Polini box, from all the test that I have seen it is a total winner. You can't go wrong with it. Functionality, power and price. don't forget to contact member(username ) PSMA, he is in azores, he is on this forum and he rides with fellow Vespa riders.

What would you say a realistic cruising speed is for your setup? What happens when you go up a hill, do you slow down? How about a 10 or 15 mph head wind? With my DR177 all those slowed me down 5-10 mph and she was screaming wide open. A realistic cruising speed was 50-55 mph on two lane highway.

^^ you are spot on. In my opinion a realistic true GPS speed for reliability is what you said(50-55 mph) if you are dealing with hills, or wind and perhaps around 55-60mph(GPS) on a flat road with little to no wind.

PSMA is from Madeira, I'm at Azores.

Okay, I will not get 70MPH, I'm fine with 65MPH, if that's what everyone is getting from this kind of setup.

I already have the Stelvio. The question is, will those parts work fine together?

I believe a VMC Stelvio + 60mm crank + 24.24 carb + some big box exhaust will work great together. I actually think that setup will have no trouble hitting 70mph, though I wouldn't expect much above that.

Three things to think about. First, you do not necessarily want to put all of the extra 1.5mm between the cylinder and the head. You might want to put some or all of that under the cylinder instead. Putting it under the cylinder tends to increase peak horsepower. Putting it under the head tends to give you a broader power band. Second, you might want to match the LML crankcase passages to the transfer and boost ports on the Stelvio cylinder. I was able to match LML cases to a cast iron Malossi 177 without breaking through. Don't know if that is possible with a Stelvio. Third, you might want to check the intake timing on the new crankshaft. I have reeds so I don't know much about that.

^^ Good to know. I just hit 68mph speedometer indicated with two riding up-right (not tucked down or hunched down) and I even went and weight myself with the helmet as well as my son with his helmet and his school back pack.

218lbs (99 kg)of your truly plus 176lbs( 80kg)=394 lbs (179 Kg round it up to 400lbs). Do I think I hit almost 70mph? he'll no!!!!

Even with just me tucked down I have hard times hitting 66-67 mph(GPS) and that is after 25 seconds of full throttle just to get that speed. It is so important that everyone uses the same standards oof measuring (GPS) so that we can eliminate the factory speedometer errors.

Sounds like my experience, I use a GPS for all measurements to help reduce error. A hill or headwind would slow me down up to 10-15 mph from that top speed. I never tried tucked down, never going to ride that way for any distance.

^^ I also don't ride tucked down with the exception of testing top speed and even for that I don't go more than 25-30 sec. Most of my riding is up right or slightly down but not much. One thing I noticed is the huge impact of what you are wearing. There are some jackets that have too much wind surface area and some of them have open sleeves by the wrist that let too much air through. Even the visor on the helmet makes a difference and having your knees within the fairing.

The tire pressure must be optimal. These small tires manifest the low pressure in a detrimental way, the tires feels wobbly when they are low. I do have to agree with you that a GPS is a must.