Modern Vespa

Had this scooter for 22 years. Been on the road and off the road several times over those 22 years. When I first got it it was fast as fuck. I was new to scooters so it blew me away how fast this thing would fly. Now- not so much. It goes... but suttins "off".


It's a '73 Sprint w/P200 that had the following done to it before I bought it
-Malossi 210 kit
-expansion chamber pipe... it's a Sc00t RS (I know ) left hand side one
-Dellorto 30mm carb

What I've changed:
-Malossi reed block...had the port machined as per malossi instructions
-full circle crank (I read that's what you do with reed conversion)
-new piston and rings (don't know why I did this tbh)
-Cosa clutch
-SIP fast flow 2.0 fuel tap
-lighter flywheel
-plus lots of other things that aren't relevant here lol

I never touched the jetting after the reed conversion... should I have? Probably a good place to start, but can you see anything else I did wrong. Are there reed petal upgrades or shit like that?

I'm 52 and don't need to be screaming around town like a dick... I'd just kind of like the option to hahahahahahahahahah.

Should be pretty fast whatever the configuration.

It's all probably not setup correctly… port timing, ignition timing, carb setup.

Everything goes hand in hand. Tweaks are done depending on the other parts of the setup (primary, gearbox, exhaust…)

Should be fun to ride.

A 2 stroke is not like a 4 stroke 'set and forget' carb adjustment. Every time anything changes the carb needs to be adjusted. This is not limited to engine changes but altitude, weather, rider weight and even how you ride. Someone else's settings for similar, will get it near but the last few adjustments have to be done by you, yourself.

Hiyah.Scooterists have for decades been throwing money at there tiny air cooled motors,and generally speaking wasted a lot of money.Nothing compares to cc's or engine capacity,I've got a 85 T5 and a standard px200efl,can't say I've been passed at all in 40 years by a souped up Vespa or Lambretta.these tuning products are all a scam,mallosi don't recommend an expansion chamber for any of there kits.The more they rev the hotter they get,then they eat themselves.More cc's water cooling.If you wanna go fast get a motorbike!

First thought, Jack221 says it straight; and he knows his stuff. With a new build like that, especially a reed conversion; the jetting needs to done again from scratch. New setup means starting all over. Few other thoughts and questions:

When you matched the intake to the new reed block, did you also remove the rotary pad? A reed needs lots of room to breath. A full circle crank will raise crankcase compression. If the rotary pad is not removed, the full circle crank will actually block the flow of fuel into the engine.

What head with your new cyl kit?

Is the kit the Sport(touring) or MHR(race)?

What ignition? and is it set correctly?

That pipe may have conflicting effect in combo with the new set up. Consider a touring box pipe, or different expansion pipe?

Cyl head and compression will need to be set differently, depending on which exhaust.

More to consider, but thats a start

Thanks for the replies, all. I should clarify something; when I said "what I bought" what I meant was what came with the scooter when I bought it.

I wouldn't have done anything else as I liked how it rode. I went with a reed setup / full circle as it appeared my rotary pad was effed... this came from an experienced scooter guy when he was changing my bearings for me.

To answer your questions specifically GeekLion, no I did not remove the rotary pad- I never read that anywhere when I was looking into the whole full circle crank thing.But I was very new to working on these then (still don't know much) so maybe I just didn't know what I was looking for. Dammit.

It is not a new cylinder kit... the kit, the head and the pipe were already there and things were fine when I first got the scooter.

Ignition is electronic. It's a Ducatti OEM stator that I also purchased (forgot to state that) as the wires on my old one were on their last legs. So new stator, lightened flywheel and harness.

Carb setup and tweak the timing look like the directions I need to head towards.

I never said I wanna go motorbike fast lol.
What I want is to learn and what I've done is taken a "fast" scooter and made it less "fast". I'd like to learn how what I've done has affected things so I can try to fix them.

While I don't think performance parts are a scam, it takes a lot more work than people think to get a tuned engine to work well and continuous input to keep them that way. Something to be said about the simplicity and reliability of maintaining a stock engine by the book. Taking over someone else's tuning project can be tough. I think tuning should be done in small steps. Take a step, make it work and learn from the experience before taking the next step.

I like it… cheers!

I'm coming in a little bit late to the game, but lemme +1 everyone who said in however many words that there's a lot more to building a fast motor than buying parts and bolting them on.

We can talk you through it, but it might take a while and you're going to learn a LOT along the way. If you're good with that program, then let's get started

First off, which of the following did you measure/test, what was the measurement, and how'd you measure it?
- Port timings
-- If you installed base or head spacers, what'd you install?
- Squish
- Ignition Timing
- Jetting
- Cold Compression
- Pressure Test

As to parts..you said it's a ScootRedacted, I assume their knockoff of the JL Lefthand pipe?

Is the crank 57 or 60mm?
What reeds? Just a regular RD-350 or something more aggressive, like Tassarini VForce4's?

What sort of porting did you do? Nothing? Just relocating/matching the Malossi? Something more?
Did you open up the intake itself?

Which Malossi head?

I assume you're still on stock gearing.

You should go ahead and get a cheap CHT and Tach. They'll come in handy once you start dialing in the carb and potentially save you from some expensive mistakes.

You're not going for an exotic build, but you are going to something that's esy to get very wrong, very fast.

And I agree with those who suggest a box exhaust. I'd grab a SIP Road 3.1. I have a similar setup on my P200 motor and it pairs nicely with the Malossi for limiting noise/discomfort while still delivering solid performance.

So it seems like your case was converted to reed after the the rotary pad was damaged. "Machining the port" suggests the rotary pad was removed and the inlet opened up, if the instructions were followed correctly.

Did someone else do the work on the engine?

If so, you should get these details from the person who did it. The changes that were made would change the jetting. Switching to a longer stroke crank is a big change and there would be a number of measurements to check (as mentioned in the previous post).

Doing it yourself is totally possible and you will get a lot of help. Chances are what you have can be made to work well with some adjustments.

There are no details. I had my engine apart and was explaining what I was doing to a neighbour- a dirt bike guy and machinist. He told me to bring the case half over and he dremeled out the inlet port to match the "template" provided by Malossi for the reed block. And that was it... he never touched anything else.

I can't find any info on the crank I switched to as Scooterworks website has changed and has no info on orders I made from them back when I used them.
Full circle Mazuchelli I somewhat recall.

What I have DOES work... just not like it used to.

Of course there's always the chance that I'm probably 20 pounds heavier than I was in 2002 slowing the bike down hahahahahahahah

If the rotary pad wasn't dremeled out and you have a full circle crank… it won't work… you're basically getting no fuel or air inside…

You'll have zero power.

Just to add, for anyone reading and wondering which crank to buy, for an OEM crankcase reed PX; don't buy a full circle crank. Even fully opened out to the max, the crank web is still in the way. Full circle cranks are great if the crank web doesn't cover the inlet (ie. piston ported reed). In this a rotary crank would go faster. Bell crank is the best option.

Here is a thread on converting a rotary case to reed as per Malossi's (often confusing) instructions. There is a lot of info out there from people who have done it. Just to give you an idea.

Reed Valve to fix rotary pad destruction

Don't know if the dirt bike guy did something like that.

Having cracked that area on my cases when they were NOT ported out like that, I'd be very hesitant to go that route on a tuned P200.

Yet another reason to go with a bell crank, IMO.

Didn't like the bell crank when I installed it…

My least favourite out of the 3 for Reed valve use (rotary, full circle, bell)

Power didn't kick in till later in the rev range.

Didn't mind full circle, just a lot more work on the crankcases…

This is the way. The modification can be a milder version of this, but either way; the pad must be removed and opened up for a reed to flow properly.

My reed conversions I have material added to the clutch side of inlet, to allow a larger intake & flowing of the case, similar to above.

A reed conversion is far more involved than just matching intake shape and run. Crankcase compression (depending on crank), cylinder port timing, cylinder port-case matching, squish, exhaust, etc; all need to be dialed in to match the build. Unrestricted flow is key. Bolt on and go is no good, especially if You want it to run well and last.

Thanks Chandlerman... I really appreciate the thoughtful post and effort. If I'm honest, I really don't think I have it in me to go that deep. I'm very much not a gear head, although I do like to have a crack at things. I'm also 52 and I hate to say it, but whatever you teach me I would struggle to grasp (in a meaningful way lol). My brainbox just doesn't absorb information like it used to.

The kit, pipe and carb were all done prior to me getting the scooter- sorry, my original post's wording was a bit misleading- I mentioned it further down the thread. I should go edit the OP. All I did was reed block and full circle crank. I opened up the intake and that's it. I really don't think my machinist guy touched the pad... but it was 20 years ago.

Pipe... yeah mine looks like the JL one.
Which Malossi head... I don't know, it was done before I got the bike.
Reed block is Malossi.
Gearing... I did find out recently that I have an EFL selector box on a PX old transmission so maybe someone in the past ticked around with the gears?

I think I'm going to start with the jetting and ignition timing for this season (it's not very long up here and I only just got on the road in the last week or so) with a view to putting my old crank back in in the off-season and consider the pipe you suggested.

I definitely did a bolt on and go

You may not get a lot of sympathy around here for having a 52 year old brain box. I'm 54 and not even close to the oldest on this forum. My greatest weakness is being a shitty mechanic, but I just can't let go of a project no matter how many times I screw up. I will keep looking for a solution before getting out of the rain or a house on fire.

Still, I get that it's not everybody's trip. You might consider farming out your engine build. Mr. Gick comes to mind, but there are other builders too. I think you would come out ahead when you factor in the time/money/assache of doing it yourself.

At this point, you seem to have a combination of parts that are unlikely to work well together. There are some unknowns too that would require getting your peanut buttery fingers in there to figure out what you've got. Shipping is cheap. Consider throwing it in a box and having someone put it right for you. You can reinstall it yourself, which is still a lot more than many people can do. Just my $.02.

Haha I hear you buddy- I just mean l have a hard time with grasping too many technical things at once- and my scooter is most definitely not the only less than perfectly running / working vehicle/ project I have in my life. It's overwhelming sometimes.
It's been suggested that I pick one thing and perfect that and move on- I think that's what I'll do.
I do like your farming out idea- but shipping is anything but cheap in Canada. It's freakin' outrageous.

Appreciate all yours and others' responses.

Yeah… other projects. Only so much space in the garage and in one's head. Both become a cluttered mess.

Where are you in Canada? I have lived in Toronto and Montreal. I have been a dual citizen since the late 90's and have family in Guelph and the Montreal area.

probably not the right guy. I would "downgrade" the engine to rotary valve and a BOX exhaust. KISS. often less is more.

lol yeah.

Guelph, eh? I'm in Kitchener- about a 30 minute drive. I'm there all the time for work. Cool town!

Should I assume there's a "cover/ gasket" of sorts to match my old intake manifold and cover up the enlargemed intake port there now?

I don't think my rotary pad was completely pooched- it was just suggested I go reed as it was a bit damaged. I still have my old crank and intake manifold.

The rotary pad is part of the case casting. Depending on how much material was ground away when the inlet was enlarged, it probably won't work anymore.

Yeah, of course.
New case half (or quality used one)and my old crank reinstalled and I'm back to where I would like to be, maybe. Might have been the answer all along lol.

Its not advisable to change only half the case, as they are machined to spec as a pair. Case halves are matched, and each half will have a stamped number to show they are matched. IE: 117/117.

Changing only half can result in mismatched bearing races, vibrations, and an even worse running engine that shakes like crazy.

You might consider splitting the engine to have a look inside. See what was done to rotary pad, check your cruciform, and give it all a glance.

You could start by adjusting jetting, and setting timing correctly; you may very well be alright without going in deep. Hard to say without knowing for sure whats going on inside.

Forget man, it's gone.

Oh shit… thanks for that.

Cruciform is brand new and I just got delivery of the correct selector box today (had an EFL one on old style transmission- not my doing) so no more bouncing out of gear.

Timing and jetting is where I'm gonna go for now.

Thanks for all the advice, as always.

Yeah man, dig in on that jetting and timing and report back. Good luck!

found this on the old scoot.net jetting database. Same kitted motor and carb with a PM tuning pipe.

0 altitude - I'm at 1000 ft, The scooter was built at 0 altitude before I got it. I should've made some jetting changes (main jet) way back then probably.

I'll take my carb off this weekend and compare.

That'll work… but won't be great…

The AV and x7 needle setup is basically off setting each other, not in a good way…

X7 top clip is super lean… to offset the AV (slightly rich)… but only a 264 which is a little lean… but maybe the 135 would help…

It'd run ok… maybe even be fast in some areas of the throttle (from traffic lights, it should wheelie). But not ideal…

Absolutely agree, doing it all at the same time just throws in too many parameters to tweak unless you have a similar setup on something else to replicate and find yourself immediately in the right ballpark, e.g. timing, jetting, etc.

Orwell, not letting go is a sign of tenacity. Nothing worth doing is easy, but having the determination to see a job thru properly is what gets it done right. I am an ok mechanic as well, but the most I have ever done outside the norm would be some mild porting and a different top end. I am determined to keep my new to me P200 completely stock with the exception of a small improvements to make it run and operate more efficiently. I'm 68 and really don't have the mind for all the tuning stuff. I'll stay at the shallow end and wave to the smarter people than me.
Scrumpadelic - for what it's worth - you may want to remove the engine and get it up on the bench to get your port timings, check out the porting done, gear set up, clutch set up and see if there is anything left to the rotary valve surface. Since you don't have all the info on the build, a lot may be just guessing and that will get you nowhere. If you go this route, you could come up with a plan while tearing it down to take measurements, take notes and lot and lots of pic to post on here. I won't be suggesting any more that this as I am clueless when it comes to tuning theses scoots. Good luck with your project and take your time.

Thanks for taking the time and for the good advice. That'll be a winter project - for now I'm just enjoying riding for the first time in 8 years. Definitely going to look at the carb and ignition timings though.

Was this checked? The case inlet has to be opened out fully for this to be safe to run with a full circle crank.

Remove the carb and take a picture down the inlet?

I think some of us are just curious to have a peek at what kinda worms you got in that can. I totally get wanting to enjoy the short riding season rather than letting those worms out. I use one of those cheap boroscope cell phone cameras to look into stuff I'd rather not take apart.

I can do that 👍🏼