OP
@scooterist avatar
UTC

Molto Verboso
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
Joined: UTC
Posts: 1550
Location: Tucson, AZ
 
Molto Verboso
@scooterist avatar
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
Joined: UTC
Posts: 1550
Location: Tucson, AZ
UTC quote
Well, first of all, I want to be fair for those of you that warned me. Rewind a few weeks ago and I was whining that my PX150 with the malossi 166 cc sounded like the engine was going to exploded on the hwy. The engine sounded hight pitch after reaching 65mph and up.

I was basically riding on Interstate with cars traveling much faster than me so I had to be at minimum 65mph and in the slow lane. I rode the PX150 at even 72-75mph speedometer indicated but it literally sounded like it could just seize.

(here is the original post) need your advise (PX150 gearing for HWY)
I called a couple of places and I did some research, to be specific, I called the service and parts department at scooter west. One guy suggested "buying a bigger bike", another guy went and explained me about the taller gears from malossi, he even told me that I could just search for a used set of P200e gears.

One of the technicians/sales person at scooter west told me that if I decided to go with the taller gears on my 150px with the 166cc kit he says that I would significantly reduce my acceleration.


Well, I ended up putting a p200e motor with a malossi 210 cc, sito plus and the original P200 gears on it. I went for my first test ride and I was all smiles at first. I was hitting almost 55mph on second, I reached 72mph in third (PX 150 speedo)but the moment that you shift to 4th the scooters loses speed and can't rev past that.


A few people told me and warned me that I needed perhaps a shorter 4th gear. Now I have a small dilema, the scooter doesn't rev as high as before while cruising at 65mph or higher which was the main issue that I had (previous PX gears were too short). The problem now is that it seems like it hits a "wall" with the rpm and it is very hard to go past that speed.

Now that I went through all of that, it makes me wonder if the malossi gear kit on the PX150 was even a reasonable choice.
UTC

parallelogramerist
Joined: UTC
Posts: 5176
 
parallelogramerist
Joined: UTC
Posts: 5176
UTC quote
Having that short 4th gear in a tuned engine can make all the difference. Though it might seem like one tooth difference isn't very much, it can be quite a bit if a tuned up engine doesn't have the torque to pull it. The old cast iron Polini 208 had plenty of torque to pull the standard 4th gear, but most Pinasco 215 and Malossi 210 kits didn't quite have enough.

I'd split the cases, install a short 4th, then that would (or at least should) get you past "the wall".

...and isn't a PX150 speedo indicating 72-75mph equal to about a 63-66mph? Get a GPS on there to get some real world numbers.
OP
@scooterist avatar
UTC

Molto Verboso
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
Joined: UTC
Posts: 1550
Location: Tucson, AZ
 
Molto Verboso
@scooterist avatar
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
Joined: UTC
Posts: 1550
Location: Tucson, AZ
UTC quote
^^ Yes, the speedometer is about 11mph off, I do use a GPS and I have tested several times before. I miss the polini products a lot. My malossi 210 is OK, it is decently fast(I have one on each P series) but I wholeheartedly agree with you.

At this point it would be a pain in the ass to split the cases. I might slap in one of my expansion chambers and go for a test ride. What short gear would you recommend?
UTC

parallelogramerist
Joined: UTC
Posts: 5176
 
parallelogramerist
Joined: UTC
Posts: 5176
UTC quote
I would recommend a 36 tooth 4th gear. If I understand correctly, you have an older P200 transmission? If that is the case, then you have the non-EFL transmission. You'll need to use a 36T 4th gear that's used in the early (old) non-EFL P125- https://www.sip-scootershop.com/main/base/Details.aspx?ProductNumber=17812400

There are differences between the EFL and non-EFL transmissions, and you can't mix and match.

http://www.sip-scootershop.com/files/catalogue/index.html#/493

You'd be MUCH better off biting the bullet, and split the cases.
As is, swapping on an expansion chamber will probably make your setup even worse. It will probably rev awesome through 3rd gear, but your 4th gear might end up being useless.
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9705
Location: Nashville

12 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9705
Location: Nashville

12 Days Since Last Explosion
UTC quote
I'd start by doing a pocket dyno (record the sound, generate the dyno off that with the GSF Dyno or SIP Pocket Dyno) and figure out what your performance curve looks like.

If you're not getting enough horsepower to push you through the air once you start to accelerate up where wind resistance becomes a serious problem, as you transition into 4th, you're screwed, with or without the short 4th.

The dyno graph and some spreadsheet work will tell you if you're going to have problems or not.

I have a sheet I use for these calcs. You can get a version set up for my Stella and modify your clutch tooth (I run a 22 instead of a 23, but other than that, I run P200E geareing), weight, etc.

The parts you really want (HP required for a given speed) required custom macro's which only work in libreoffice draw, but it's free/open source software, so don't let that hold you back. In case that's too much work, I've added screenshots of the graphs for a P200 setup.

Also, after you got the 210, did you confirm it's set up correctly by the PO? Jetting, port timings, squish, any porting work done, airbox flowed to carb properly, no leaks, etc.? Each of those can make a big difference.

Once you know the exact nature of your performance issues from the dyno and can confirm that the motor is already being all it can be, then you can figure out exactly how your current setup is failing rather than just trying stuff or throwing money at it and hoping it gets better.
HP required at the speed you'll be at by RPM for P200E default gearing
HP required at the speed you'll be at by RPM for P200E default gearing
HP required at speed in MPH for P200E default gearing
HP required at speed in MPH for P200E default gearing
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