Oh yes. No problem. Your engine should be able to pull the bike up to at least that. About 75 mph is the theoretical top speed with that gearing. I don’t think you will need the Scorpion pipe, as a matter of fact I think the Sito will be a wiser choice, since it has a broader powerband (read: easier to pull the gearing at lower revs). Also, it is much more quiet than any real expansion chamber.
You’ll loose some of the hp at higher revs with the Sito, but you will get a bike that is easier to drive around town/at lower speeds.
Running the Polini 177 with the original carb is not advisable, especially not with an expansion chamber fitted. (Hot, hot!) Consider fitting the SI 24/24E (Piaggio original from the P200) to get enough cooling at higher speeds. You can keep the autolube, the carbs are identical except for the increased size. The original inlet (not the carb) of the PX125 is a huge bottleneck, by enlarging the transfer ports to suit the Polini 177 and widening the inlet by 2mm front and back you will get a really feisty little engine!
People are often referring to the Polini 177 as seizure prone, but I think different. You need to run it in very carefully (at least 900 miles/1500 km), set the ignition dead on 19 degrees and make sure the carburation delivers enough fuel to cool the piston crown properly (read: at least 24mm). Also, fit a NGKB9HS or equivalent heat range spark plug. If carried out, the Polini 177 is as reliable as any other tuning cylinder for the PX125. By using an octane booster, you get rid of the pinking/knocking which can be a problem when running at higher revs. Not all Polini 177’s have this problem though.
Original von pyperb:
I read your post with interest:
So if I just buy a Polini Upgear kit and say a Scorpion pipe this will be enough to get me to 70+??
I would like to keep my existing carb cos the autolube but if I don’t change it will this become a bottleneck??
Also if I add these goodies is there more change of the Polini kit seizing?