rb 225 or 250 your Opinion

[sean brady scooters]

all malossi kits use exposed studs ,wether ally or cast,166,172 210....

pinasco use enclosed ,which seem often to suffer from 4 point siezes.
polini use half and half...

[tony]

yeah but that pinasco issue could be down to dodgy cast material, crap pistons or simply too tight a bore clearance.
Sean, mugello is that exposed or enclosed?

[sean brady scooters]

i dont know tony,
hav,nt got one here,and so cant check matey.....
i really dont know what difference this all makes myself,its just an observation.....

but i,m sure charlie could shed some light on all this...
let me know if you can....

[tony]

ok.. its an interesting one.. falc is enclosed.. The barrel has to remain more stable with the more metal there. Less flexing to be sure.

[johnd]

yeah but that pinasco issue could be down to dodgy cast material, crap pistons or simply too tight a bore clearance.
Sean, mugello is that exposed or enclosed?

Mugello are enclosed.
I seem to remember reading somewhere of people using a grinder to open the polini 208 stud channels up between the fins to aid cooling.
Would this work?

[GPMatt]

it should, i mean- afterall, the studs are only to line up the cylinder, the cylinder head will secure all sealing faces are tight- providing it is straight.

by drilling them out, you may have 'play'.



Also, the RB 250 studs are no closer to the piston than the falc 150 studs are. The only difference is their location around its circumference.

eg: 2 are closer to the exhaust port side of the piston on the RB, however i've not heard of any 'well built' RB's seizing on 4 points which would indicate heat retention in the studs.


just food for thought....

[sean brady scooters]

but,on vespas,specifically 200,s they have a locating stud in barrel base to crankcase mouth...
t5,s have the sleeve around one stud in the head.