Px125/150 upgrade.

[Meds]

This is my first foray into P range upgrading and tuning so im aftter some help.
I'm looking at building a balanced every day bike based around a small block P range engine that's capable of providing P2 or better performance and reliability.
So here goes
BGM 177 kit (I have their RT195 kit on a lambretta and like it)
60mm crank ( probably mazzucchelli)
SI 24 g T5 carb
P200 gearing
BGM box exhaust,

I have chosen the the BGM kit and exhaust as I have a RT kit matched up with a BGM clubman and they work well and make it easy to ride.

Not sure about the gearing or the carb choice.
I have read that using SI carbs with 60mm cranks can lead to failures.
I have also read that the SI24g carb is as good as the SI26mm.

[boxofbits]

I am thinking the same set up but with a phbh 28 carb Can't find many people who have them set up yet with some miles under there belt,but willing to give it a go.Gearing was going to leave it and see what it like

[Meds]

this kit doesn't seem to have much use yet, I'm sure someone will have a bit of info
Looking at the dyno graphs and the power it's outputting I figured taller gearing would suit it better.

[sean brady scooters]

what do they reccomend with the kit ,prob best to follow their advice on such matters

[Padge]

most (if not all) small block vespa kits will benefit from upping the clutch from a 21 to a 22 tooth sprocket (most wont pull the 23 of the 200) leave the rest of the gearbox "as is" and DO NOT put a p200 4th in it! malossi and polini large block kits recommend/use a t5/px125 4th gear or they die on their a$$. A sip banded cosa clutch with sip fast road springs and newfren plates
If using a crank with modified inlet duration they always seem to not run just quite right on an si carb so I've always found them better with a 28/30mm pwk or phbl
as for exhaust, i'm sorry, but no box exhaust will come anywhere near a decent expansion (and there are many many dyno charts to prove this)

[Meds]

Cheers Padge.
Might need to rethink my set up.

[Padge]

yer welcome Paul

[cartmel808]

I have a DRT 22t clutch gear & 65t primary combo with an otherwise standard px125 box in my quattrini m1xl... 1st & 2nd gear are still very short... even with the up-geared clutch & primary - so I would suggest fitting a longer 1st & 2nd cog to the 125 box.


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[hat]

The one thing i would say is that the 24g T5 is not easy to set up correctly for a PX. The range of jets available is much smaller. You would be better off going with the 24/24 P200 carb

[Bofs]

Simple and easy option...buy a P2 engine, sell your 125 engine, total outlay maybe £300. Job done.