Do I or Dont I upgrade from Sitoplus to PM


I phoned PM Tuning and asked their advice to get my Vespa PX125 with Polini 177 running a little faster. He said upgrading my sito plus exhaust to a PM may add a further 5mph and take my scoot from 65 to 70 mph…

Is he still try to sell me an exhaust or is he right??



Hey ArmedForcessccatterick ta for the cyl head info…I did not realise that there was so much difference between the profiles done by different tuning houses.

I was beginning to wonder why the squish band on my Taff/Malossi head is 2.6mm (without the head gasket). I know it’s not as easy as that to workout, it’s all to do with cylinder head volume, compression ratio, stoke and stuff like that. I was gonna try to work it out with the Norrie Kerr book, but if PM tuning know it all already and can carry out the work, I’d happliy give it to them to do. BUT is your price quoted right that reads 101 Pounds for a head & re-profile job right?


i think the PM would probably be a good idea but get the engine set up properly. as one of my mates didn’t and it completely messed his engine up and it actually ended up slower than it was in the first place. now another one of my mates got his PM and then got it properly fitted and the engine set up and it made the world of difference. it was around 10mph faster.

hope this helps you decide.

by the by, another good performance pipe is the taffspeed goldline, i use it and it makes a good difference to the kitted motors. [:drink:]

Alright mate,
if you do decide on a PM make sure your head is profiled and in good condition. It took me two pistons to find out that a PM pipe doesn’t work all that well with a Taffy tuned head, so now I’ve had to fork out £85 on a new piston as well as £101 for a new PM profiled head. They do put a decent whack onto the top end though!
Keep scootin![:smile:]

Hi All,

I had my kit done by Midland Scooter Centre on a brand new PX125 so it should have been installed correctly…or set up properley like scooternut says.

I thought it was only Malossi 210’s where the head had to be reprofiled…is this the same for a 177kit???

How do I check what the main jet settings are on the scoot?
and what is the best gearbox sae 30 brand to buy?

Thank you all,



Greetings, in my opinion yes using a pm pipe will help that is if you have fitted with a bigger carb and have your valve an extended opening or reed valve, but if your using a standard carb then stick with sito, hope this help .

the price I quoted was for a brand new head + £30 to profile it then VAT on top.
2.6mm is quite a big squish band though. You only need 1mm at the outer edge to allow for piston expansion so the crown doesn’t hit the head.[:smile:]