Modern Vespa

Morning guys,

I just bought a stock 2005 PX150 and am thinking of bolt on ways to get the most out of the stock cylinder and gearing without opening up the cases. Money is tight (getting married) so this is a wedding present to myself. Please take a look at what Im thinking and if youve got any recommendations let me know.

-Swap stock clutch cog to a 22 tooth
-Box exhaust
-T5 air filter
-Larger volume carb box cover
-Remove the E-start flywheel (doesnt work/ dont use it) and put a SIP touring flywheel on 1600g
-Anybody know a supplier for a 150 machined head? Something with the combustion chamber corrected for better performance/ better cooling? Hot Rod Al used to offer this service.

Am I missing anything?

I just read an article, where was that? They pulled the cylinder and reworked the exhaust port also. Raised the power output by 50%

https://www.scootering.com/scootering-classics-vespa-tuning-upgrade-mega-feature/

Congrats on the upcoming marriage. Mazel tov!


I'm really no help on tuning at all.... sorry. I did put the SIP road and up-jetted my carb on my PX150 (and stayed at a Holiday Inn Express). Moderately more pep, but still really pales compared to the torque on my P200. I will be curious about your results and impressions after your upgrades.

https://www.scootering.com/scootering-classics-vespa-tech-part-2/

Looks like they raised the cylinder 1.5mm and decked the head to bring the squish down. I'm definitely interested in trying this....

Might as well open up the exhaust port while you have it opened up on the bench. It's cast iron not hard to do at all, and fairly forgiving, I found that out when I got my hands dirty.

Congrats on getting married. I did some upgrades on my PX150 shortly I purchased. I am the type of guy that likes to go out and measure the speed with either the GPS or the performance measuring electronic device called drag.

when I first got my PX150 with 3200 miles on her she only had a sito plus. I used to read 58mph on the speedometer tucked down which later end up to be a 50mph real top speed.


The first thing that I did was to install a Malossi 166cc which I will tell you straight up I am not impressed with but at least it increased my top speed 16 mph. I have been able to read 75 mph on the speedometer tucked down going downhill and 70-72 mph on a flat surface (tucked down). I also ran a 24/24 carb.


I am not thrilled with the malossi 166cc because compared to the poling 177cc (iron kit) it is a dog. The polini had more torque and more punch.

I am now on a swapped P200E cases and running a malossi 210cc with a 26mm carb and a expansion chamber but the tall gearing is kicking my butt, the scooter falls on its face after I put it on 4th gear. People warned me about it so I am taking the blame.

long history short, with the malossi 166cc I use to be able to rev the hell out of it even in 4th gear. now with the tall P200E gear and much larger engine I can't use my top end because the wind makes it hard to get into the high revs and use the top end in 4th.

As far is pinasco? I rather jump from a balcony before I ever put a pinasco cylinder kit again, even if you give me a free pinasco I wouldn't put it on my scooter after the terrible experience that I had with it. Pinasco crumbled like blue cheese.


You still have some interesting choices out there like the BR kit or the BGM. I would't necessarily invest on a carburetor, my PX150 achieved the same top speed with the 20mm as it did with the 24mm. people can tell you otherwise but you can tell the people to please invest on electronic measuring devices like I did and record their acceleration times then prove it.

By the Way, I like some of the mods on your wish list, like the flywheel, the carb box, T5 air filter. I always had good results with the expansion chambers specially with increase top speed.

Good luck with the project and congrats on the PX150.

I'll definitely open up the exhaust port too. Going to measure timings and squish to see what I'm dealing with this weekend.

Scooterist- I appreciate the kitting suggestions. I currently have 4 scooters 200cc + so I'm trying to do everything I can to keep it a 150. I also want to challenge myself and not open up the cases.

I'll be interested in what you end up with doing MJ. Many moons ago I had a beautiful PX150 but sold it after talking to HR-Al. I didn't want to drastically change the engine to go 60. So I sold it. Why, why, why, did I sell it! Aaaarrrggghhh.

You can open up the transfer ports without splitting the case. Get some foam that is a higher density but still squishes and cut it out and plug up hole for the connecting rod. Grind away, then vacuum it out with a shop vacuum. Also look up O tuning from freaky.

Don't know squat about tuning, but congratulations and best wishes for you and your bride!

Cheers to you and your fiance!

MJ, i know you don't want to split the cases, but you'd be loosing out on lots of free HP and torque if you didn't. The cylinder to case transfers are terribly mismatched on that PX150. So no matter what you do porting wise to the cylinder, you won't reap the full benefits. Christopher mentioned sealing off the area then doing the grinding, which you can do. I think a safer way is to split the cases, BECAUSE it will allow you to flow the carb, carb box, and intake all together. And when the cases are apart, you can double check what shape the giblets are inside (which is a great time to replace the shift cross). Matching the cylinder and carb flow will give the scooter significant boost in torque and a bit more top speed. And if you decide to do additional cylinder head or port work, it will only make it better since you have the proper flow.
I've had four of them (at once), so i'm fairly versed with the '05 US PX150.
My list goes something like this...
-new engine gasket set.
-new shift cross.
-new fly side bearing and seal (because they're small and prone to lots of wear).
-flow the barrel to the case.
-flow your stock 20/20 carb and box to the case inlet.
-box exhaust (i happened to use a Sito+)
-keep the stock filter.
-keep the stock airbox cover.
-I'd try that 22T clutch as well.
-keep the stock flywheel (because it's fairly light, when compared to a stock P2 flywheel).
-a new small end con rod bearing and clips.
-for extra credit, you can polish the con rod up.

That list should let you cruise at a true 55MPH (stock is around 47-48mph). It will also keep you away from a machine shop for the time being. That (super inexpensive) list it will give you the best bang for the buck, and you'll have a quick turnaround time to get it back on the road.

And you do know that the PX has a clutch innerlock switch right? So if you don't pull in the clutch lever, the starter won't engage. I'm just wondering why it doesn't work. Post up pics of the PX!

And the speedos are so far off on the PX's, that you can't base anyone else's claimed top speed on theirs unless it's verified with a GPS. Make sure to get some baseline speed numbers from your GPS before you start on any mods.

[quote="scooterist"]Congrats on getting married. I did some upgrades on my PX150 shortly I purchased. I am the type of guy that likes to go out and measure the speed with either the GPS or the performance measuring electronic device called drag.

when I first got my PX150 with 3200 miles on her she only had a sito plus. I used to read 58mph on the speedometer tucked down which later end up to be a 50mph real top speed.


The first thing that I did was to install a Malossi 166cc which I will tell you straight up I am not impressed with but at least it increased my top speed 16 mph. I have been able to read 75 mph on the speedometer tucked down going downhill and 70-72 mph on a flat surface (tucked down). I also ran a 24/24 carb.


I am not thrilled with the malossi 166cc because compared to the poling 177cc (iron kit) it is a dog. The polini had more torque and more punch.

I am now on a swapped P200E cases and running a malossi 210cc with a 26mm carb and a expansion chamber but the tall gearing is kicking my butt, the scooter falls on its face after I put it on 4th gear. People warned me about it so I am taking the blame.

long history short, with the malossi 166cc I use to be able to rev the hell out of it even in 4th gear. now with the tall P200E gear and much larger engine I can't use my top end because the wind makes it hard to get into the high revs and use the top end in 4th.

As far is pinasco? I rather jump from a balcony before I ever put a pinasco cylinder kit again, even if you give me a free pinasco I wouldn't put it on my scooter after the terrible experience that I had with it. Pinasco crumbled like blue cheese.


You still have some interesting choices out there like the BR kit or the BGM. I would't necessarily invest on a carburetor, my PX150 achieved the same top speed with the 20mm as it did with the 24mm. people can tell you otherwise but you can tell the people to please invest on electronic measuring devices like I did and record their acceleration times then prove it.

By the Way, I like some of the mods on your wish list, like the flywheel, the carb box, T5 air filter. I always had good results with the expansion chambers specially with increase top speed.

Nothing wrong with the 166, you need to run a proper carb (Dellorto phbh30) and be prepared to convert to reed valve.
A flowed crank, 22t upgear and nice sport expansion you'll be eating GTS300's all day long.

Congratulation on getting marriage, if u were close i will hug you for sure

As for the 150cc original tuning, welcome to my world as i seek the better performance of the standar engine for years, i once have a polini 177 given from Brother M but shamely i damage it so back to standar once again

As for ur list the 22 clutch teeth is the best as i once try the 23 and i lost badly in 4th gear, for my next enginue i will use 22 sprint clutch teeth with px150 efl gearing as well, already had the worst skin on the barrel as its flat and i will make the transfer port in the cylinder to almost straight and yes raise the exhaust port and maybe i will make my own homemade big box exhaust.. And yes stay in 10" tyre, will work on the timing as i probally will be using a lighter flywheel, oh yes i will modified the carb to have a fast flow fuel as well

Good luck on the wedding and the project as well and cheer

Just stick a SIP 2 on it, up jet, that's all you may need.

So here's the latest plan for the build-

Open up the exhaust port
Machine the head
Deck the cylinder
Raise the cylinder up 1mm
22 tooth clutch
Switch to a 24/24 carb
Add the Polini 24 Vortex kit
Switch the flywheel to the SIP touring
Switch the exhaust to a Sito+ I have lying around.

The piston has seen better days and the cylinder was seized both on the intake and exhaust sides. I'll buy a new piston tonight but just hand hone the cylinder. A lot of the stuff listed above I have already so it'll help keep the costs down.

Are you going to the next size up piston? If not Looking at this piston if you o-tune it a lot of the marks would go away. Could also be a good chance to try it for the fun of it.

I like that list but would substitute the polini Vortex with a T5 air filter and Pinasco Box cover. My preference is to maintain the stock bellows and cool clean air.

Oh man, a Series America! I love the color MJ and am sorely disappointed in myself for selling mine many years ago. It just didn't have enough speed, and I didn't want to spend a couple grand, or tweak it because it was in great shape.

After talking with HotRodAl on the phone, it all just was adding up to be too much to spend at the time. Now I wonder....

So I just wanted to add an update to this project. Unfortunately all the replacement pistons I'm finding are for low compression early model PX's so I reached out to Hot Rod Al for advice. He's going to help me fit an oversized smallframe Polini 57.8mm piston into this cylinder. I'm not sure what black magic it takes to make that work, but the thinner piston rings and rings closer to the top work better in higher revving engines. I wanted this project to be special and its definitely getting that way!

Hopefully in the next few days my piston will be delivered from SIP and i'll have more updates and pictures for you all.

Who is turning your cylinder for you?

Just wanted to add an update. The marriage has been delayed until July for worldwide reasons but Hot Rod Al got the smallframe piston to work and raised the cylinder 2mm and did his black magic on the rest. Head was decked and reprofiled for touring use. Ignition and flywheel stayed the same. I removed the air box thinking I would have to machine it some to fit a 24/24 carb but it was already opened up enough. I swapped the 20/20 for a new 24e Dellorto, no Vortex. The clutch I wanted to rebuild as the stock 150 Cosa springs were way too soft for my liking. While I was in there the plates were new so I used the old plates but installed the new Malossi springs and the 22tooth center. The spare Malossi plates are sitting on the shelf for another time.

Anyways acceleration is as much as a P200 in the first 2 gears. 3rds ok but 4th is a long linear climb to top speed. Tucked in with good temps I got max 62mph (GPS). I'm going to ride it for now but Scooterwest has Malossi 166 kits for a pretty good price so I'm tempted to slap one of them on and see what kind of speeds I can pick up with the bolt on top end.

I've been following this since the thread started and I've read all the Scootering articles. I've got a nice Stella, mostly stock except the exhaust and the air filter. It runs great, but it it can always be better, right?

The idea of opening up the exhaust port and skimming the head seem like really easy, really attractive options to just make what I've got that much better.

I've even got a spare head and cylinder I could send off, but then I need to re-seat the rings correct?

If I'm following all this correctly I:

1. Pull head & measure squish.
a. head currently uses a copper gasket and has a groove machined in the mating surface. Do I need to replicate that?
2. While waiting for that
a. cut new base packer gasket
b. raise exhaust port slightly (I get lost with all this port timing stuff)
3. Put back together and haul ass with 1-2 more HP.

Is there anything I'm missing? They do this to a PX125 and I've got a Stella but I'm guessing the process is pretty interchangeable.

I'm also operating under the assumption that this is all just "optimization" and so I shouldn't see much of a difference in reliability.

Thoughts?

Hal

Hal,

Take a look at this link. https://www.scootering.com/scootering-classics-vespa-tech-part-2/
This should answer all your questions.

Since I dont have a local machinist I reached out to Hot Rod Al and he helped me out when he wasnt doing his other work. The only thing different that we did from that article is raise the base up 2mm and rather than use paper gaskets, I bought pre made aluminum base gaskets from SIP. Al says the paper ones eventually compress and will cause leaks.

No groove in the mating surface for the head, both sides have a raised circle. You can completely remove the gasket if you polish and true up both surfaces on a flat piece of glass. I use a spray copper gasket material, between the surfaces once polished.

You can clean up the intake also. Remove the bar between the two reeds in the reed block. Then put in ggr hot reeds or rd350 boyesen reeds.



https://youtu.be/90NgpMjWcCk

Just wanted to follow up on this thread in case 8 years from now someone responds.

I stopped with the HR Al smallframe piston in a stock jug, 22 tooth clutch cog, 24/24 carb, Polini box exhaust. That was getting me to 62 mph fully tucked in top speed.

I splurged for a Malossi 166 kit. Bolt on it got me to 64 mph. Couldn't Get any further due to gearing.

Splurged on the Cosa 2 upgear kit. That combined with a Sip road 3.0 I'm now topping out at 72 mph, fully tucked in (200 lbs). I could probably squeak a few more out if I matched the case transfers but I wont.

Hope this helps someone down the line.

Sounds impressive MJ!

Just wanted to know how the performance of the SIP 3 differs from the Polini box?

My butt dyno feels more low end grunt and the biggest thing was the ability to rev out higher. I dont remember the exact increase but I definitely did get a few more on the top end once I switched from the Polini.

Fit was better on the Polini but enough cursing and a soft mallet got the Road 3.0 to fit. Ive since sold my Polini box to Scooterist's friend in AZ.

Cheers MJ. Clearance to the ground wasn't an issue I take it?