Modern Vespa

I have an '87 P2 EFL engine stripped and ready for rebuild. I need to decide whether to go for the new Polini 221 or the Pinasco 225 set up with a 60mm crank and up gear. I'm after good reliability, two-up 65-70 motorway cruising, good hill and headwind performance and decent fuel consumption. At 65-70, I want to keep the RPM sensible. I am happy to open up and profile the crankcase ports a bit, but nothing excessive and without needing to build out and weld the cases.

I have heard that the porting required for the Pinasco is quite mild. Does anyone know what's required for the new Polini kit? I'm after low-end and mid-range torque, rather that high-end RPM, hence Malossi is not for me.

Cheers
Steve.

Some info here - http://www.scooterotica.co/forum/viewtopic.php?f=8&t=28633&sid=6b0062555cf8151bbf95ba2dbf11b7fc

I am definitely not an expert on the subject of tuning Vespas but I have been around long enough to know that cruising (as opposed to WOT) at 70 mph two up means you are looking for a fully tuned motor. A Malossi with a shorter top gear would not be too hot. A Pinasco kit would need additional cylinder porting to make the power you require. I think you are looking for a motor that makes at least 20 hp.

ive built a couple of pinascos. The one im working on now is a 225. im 9/10ths the way there.
The vrh head needs to be bought seperately, which meant extra expense. Mine didnt match up very well with the base...to put it mildly it was a bloody nuisance. Also the exhaust stub is moulded in and is about 10 mm off what it needs for a sip road road to fit conveniently. Next time im going polini.

My 225 is still in progress
So im saying stay away from the 225. And ive not even started the bike yet

cheers

Chaps, thanks for your responses:

Ginch, that other thread discusses the Polini kit that I am considering (the one that is out of stock just about everywhere). I'm edging towards it, so long as I don't need huge crankcase ports to get the best from it.

crock, you are correct. I'd be happy with 65 mph cruise with my wife on board. We are 140KG combined at most. We've been using the PX150 lately, so a good step up from there will make us happy enough.

@Trumpy, interesting take on the Pinasco option. Do you know if the kit has been revised/improved lately, because some places refer to it as the 'new Pinasco 225 kit?

na its the same kit as the 215 except the long stroke makes it the 225.

The supplied head is the same for both kits

*edit* the only thing new about it is you can buy a vrh head for 225

I have a Pinasco installed on my P200E engine on the Rally. It was done about a month ago, and I've been overseas the past 3 weeks or so which means I have only had a few rides to date.

The porting was done by one of the scootershops in Melbourne and wasn't a huge job. Doesn't have to be done, but I think it was worth it. I don't have the 60mm crank and from my initial riding it seems lovely with great torque. I used a Worb head on it.

I also replaced the 4th with a shorter one and that has made a great difference as well.

My pipe is a Sito Plus.

All up, and again, I have not ridden this enough yet, I love the set up and it feels like it will be a very reliable tourer.

Good luck with your bike, your combined weights should be great on the bike.

btw, there is a new Pinasco kit on its way as well. There is a thread mentioning it on here.

disc valve or reed valve? (Page 2)

I think this is the one from the SIP website

http://www.sip-scootershop.com/en/products/racing+cylinder+pinasco+215cc+_81110000

Alan that one is the standard pinasco. same as i bought

forgot to add you also need the sip exhaust stub kit as the OD of the stub is smaller than a sip road (if thats your exhaust to compliment)

http://www.sip-scootershop.com/en/main/base/Details.aspx?ProductNumber=13014000

Ooops, my bad. I just read the 6 ports. Tut.

Any views or real life experience of the new Polini 'Evolution' kit (221cc)? Are Polini kits generally closer to a Malossi screamer or a good alternative to a Pinasco for reliable fast touring? I don't want a rebuild on my hands every three months !!

Looks like JimVanMorrisey got one - https://modernvespa.com/forum/post1680716#1680716

Not to start an argument but why would two people on this topic refer to a shorter 4th gear? Don't you want to stay with the stock gearing or event higher?. I get the point that the 4th gear would get there quicker but you are reving higher thus now you are creating extra heat on the engine thus reliability might be an issue.


I have a P200E with a stock 200cc but before I use to run a Pinasco 215 and a 226 Hotwing and I found the stock gear more than sufficient for the job. I also have a Sprint veloce with a Malossi kit 210 and a expansion chamber and again I find the stock gearing more than plenty but I just don't see shortening the 4th gear helping any.

I always said that going over 60-65mph on these scooters is simply nuts, safety is a big compromise. I had a flat tire 22 years ago on a Vespa PK75XL while I was riding at only 35-40 with a passenger and the tire loss air rapidly due to a puncture and that was extremely hard to control, we almost went to the floor and crashed.

At the end of the day I believe that I am sae to say that maintining a real(real GPS) speed of 65-70mph with two person up-right is asking a lot and risking a lot. My .2c

Hello

The safety issue is an interesting take, i wonder if that is why vespa never pursued a 200cc T5 .

Any thoughts on it.

Grumpy

I guess if you want to be safe then buy a Hummer. Otherwise, keep riding!

Actually it kind of annoys me that all the drivers who buy a bigger, heavier car/suv so they will be 'safe' are making it so much less safe for the rest of us.

The short 4th is to create a closer-ratio gearbox, that will allow you to run a peakier expansion chamber and not drop off the pipe... is my take on it. A friend found his top speed rose by installing the shorter 4th (166, Vespatronic, Simonini).

Hello

I have heard this about the short 4th also a huge help on minor gradients.

Grumpy

I have the stock 200 gearing and it's fine on the flat, but at a certain speed (maybe stuck behind someone) going uphill I find I'm constantly going back and forth between 3rd and 4th.

here's a full explanation. *caution* math ahead.

when you tune a two stroke, you typically trade a down-low wide power band for more power in a narrower range higher up in the RPM range.

this causes two problems.

first, it can make your existing gearing too high.

when you move the stock power peak from the stock spec of 5700 rpm to 7000 RPM or even 8000 RPM (the polini 208 is spec'd to develop peak power at 7900 rpm, but 7000-7500 is more typical in the real-world) your road speed at the power peak goes from 62 mph to 76mph or 87 mph (82 at 7500)

obviously, slapping a kit on isn't going to make your bike do 80. you don't have the power to pull it. because of this, you'll never reach the peak power and your kit won't be able to really work its most efficiently in top gear. if yo have a passenger, and hit headwinds or an incline, you can lose RPM, lugging the engine until you fall off the bottom of the power band.

the lowered 4th does not drop gearing much; it's about 3%. this drops your speed about 3 mph at the power peak in the 7000-8000 range. at 7000 rpm, your speed becomes 73 mph, and you now hit 76mph at ~7250 rpm instead of 7000.

second, a narrowing of the power band decreases the 'overlap' you have when shifting between gears.

this same 3% (isn) drop in top gear can be done by going to a 22 tooth clutch. why do people swap the 4th instead? because of the overlap.

a stock p200 makes peak power at 5700 rpm. in 3rd, this happens at 46 mph.
when you max out and shift to 4th, your RPM drops to 4250. stock engines have a very wide power band so this isn't so much of a problem. the power overlaps between gears.

however, when you tune the engine, you start to push the envelope. to illustrate this, i've attached a random dyno graph from the internet from a p200 with polini 208, no porting, and a taffspeed pipe.

so, on this graph, you shift out of third at 7000 rpm, where the power drops off. At 7000 in third have 14hp, and you are going 57 mph.
shifting to 4th with stock gearing, you move to 5200 rpm, and 11 hp.
however, -with a lowered 4th-
you enter 4th gear at 5425 RPM, and about 12.5 hp. this increases that overlap.

this 225 rpm drop in gearing moves you further up your horsepower curve, and gives you a cushion to prevent you falling off the bottom of the power band.

so in this example, at the expense of about 2-3 mph on the theoretical top speed, you gain 1.5 hp ( almost 15% more power!) while you are accelerating into 4th. that 15% more power is what can help you fight hills, headwinds, and carry a passenger.

in a more extreme-tuned engine, this becomes even more pronounced, to the point of where 3rd is just as fast as 4th because you can't get it into the power band. dropping the gearing by both dropping 4th and a tooth off the clutch can be beneficial in these cases, because any decrease in top speed you might loose with the lowered gearing is made up for by spinning the engine faster.

my Ape 50 has a similar problem right now, because i got too ambitious with the gearing. it'll hit 50 in 3rd, but drop to 40 slowly when i shift into 4th unless i wring the shit out of it in 3rd and come to a downgrade.

(when that happens, it gets freaking ridiculous though. 65+ in a tippy 500 lb small frame with a 2x3x4 cage around you at 9000 rpm can be refreshingly terrifying.)

Thanks for that.

Grumpy

Wow - thanks Rob for the thorough explanation - makes total sense now that you've explained it.

Thanks again

Rob,

I read your response towards me, it seems like you have the good theory in numbers (the math), I somewhat agree but I am a firm believer that to do the real test with real numbers you would have to take these 3 main readings:

1) RPMs with a tach
2) EGT to see if the cylinder is running efficiently
3) GPS real speed

To me a real test would be comparing two almost identical set ups but one with the stock gearing and the other with the shorter 4th. Right now no one as far as I am concern has probably done a back to back situation with the cylinder kit, two people up right at 65-70mph and changing the gearing... do you know what I mean?

Gearing has very real effects on how your scooter performs and is in my opinion one of the most overlooked bit of scooter tuning, except maybe amongst lambretta people.

an interesting side-note - when i worked at genuine, we did a model called the 'atomic fireball'. it was a bone-stock stella except with a 23/65 primary instead of a 21/68. it wouldn't pull 4th with a passenger. (unless you ditched the cat converter pipe) we gave one as a gift to the company in california that did the emissions testing for us. we later found out they put it thru the tests, and it actually managed to fail emissions because of the raised gearing. it was a great ride with a sito and one up, but a lot of people found them to be faster when you went to a 22 tooth clutch.

honestly, side by side isn't the real test on this, a dyno would be. accurate measurement of RPM, exhaust gasses, and real wheel speed without the variables of driver/passenger weight, windspeed, incline, etc.

however, since changing the gearing doesn't change the power curve, you really don't have to do the test. calculations of where on the power curve the transitions between gears fall show you really all you'd need to know.

In the example i posted, having 15% more power when you enter 4th will help you accelerate faster. there's really no way around that. it gets even more pronounced as the power band narrows with more aggressively tuned engines.

i've done a ton of playing around with gearing back in my race days and ran pretty much every possible combination of 35 and 36 tooth 4ths along with 20,21,22,and 23 tooth clutches on a 65 tooth primary. i was rebuilding that thing almost every week and was constantly swapping the gearing- even to the point of swapping to different gearing based on what track we were running next weekend. as i also ran that bike as a daily rider, i ran a lot of miles on it and it does match the math theory.