Modern Vespa

well...

recently i installed a polini 9 roller vriator for a forum member in Belgium(note it's a 125cc IE just like i have), i noticed he had a problem that his belt has been rubbing against the engine casing badly at the front pulley.

he told me that this was since he put in the Dr pulley 6,5gr sliders in his stock variator and he was forced to go back to the stock rollers.
hence the polini variator, he liked some more acceleration.

Wel this got me thinking because i have the same exact engine and Dr pulley setup if mine was also rubbing that badly.

So i took the cover and variator off and i noticed mine was only rubbing a little, nothing to worry about but is seems that my engine casing was a bit deeper at that point then that forum member's casing or am i incorrect and is there no difference in dept ?



ps the interval between opening his variator and mine was almost a week.

ps2 : i ut in the red springs in the clutch while i was at it to see of this will make the acceleration faster without bogging but i will report in another thread about this when i had the chance to test it.

if you do a search, I believe than groove is machined into the tranny case....
and not from belt wearage....now there is a set up that will rub, but I don't remember off hand how that is...

no, i'm sorry but you need to believe me, those groves in our engine cases are clearly not machined, i forgot to take a photo of it but it is really due to wear of the belt rubbing against the casing at full speed.

the Dr pulley setup is notorious for this problem but i tought it was only happening with people that are using higher weights to get less RPM at full speed...

he and i are using the recommended 6,5gr sliders as suggested by Dr pulley site, these should not make the belt rub against the casing but they clearly do and here comes my question why is his more grooved then mine ? (hence the refferal from me that my casing seems to be a bit deeper so it seems the belt can't rub that fast against the casing).

We don't have the GTS125 here in the US, but I seem to recall that there was a change to the engine case of that model a while back, moving the oil filler / dipstick from the left side of the engine to the right side.

I believe you that the belt is rubbing, but there really is a factory-machined groove in there as well, which is actually slightly misplaced in that it doesn't match where the belt actually rubs.

Your friend could have also gotten rubbing due to mis-assembly. If he put the thin washer on the outside of the outer half, instead of between the outer half and the gudgeon pin (bushing), you would definitely get belt rub at WOT.

that is correct, the IE version's that i and the other member have are the ones with the dipstick at the flywheel.

ok there is a machined slot already there(i think i remember something about that) but his was positively rubbing, as far as i could see the spacers where in the right place when i was mounting the polini...

There is an article from psn tuning about various aftermarket variators from a few years ago that described a rubbing belt when an aftermarket belt was used in combination with some of the variators. Is your belt stock Piaggio?

Mine is but i can't remember if the other guy has a piaggio belt...

Good point, i'll give him the heads up ! Tnx !