Modern Vespa

The stock roller wights in a Liberty150 are 15.4gm....ScooterWest sells a 'performance kit' which includes rollers nearly 3gm less!

These much lighter rollers will give me "a huge unlocked power increase", per SW.
I'm no expert on scooters - but my experience has been that were I to use these much lighter roller weights my engine rpm's will significantly increase all across my ground speed - until top speed is reached.

So my engine will be revving at higher speeds - and I'm sure that translates to more powerful pull-aways from a stop....and 'power'! any time I goose the throttle. Because I'm simply carrying more revs.....all the time.

Yes? Or am I mistaken?
Because constantly carrying more revs seems like a good thing for those who don't mind thrashing this little air-cooled engine.

For those few of us who don't WOT their scoots...what say you to us?
What am I missing?

O.S.

I have the Malossi Multivar kit installed which includes the lighter weights.

Seat of the pants tells me the engine stays in a higher RPM range at all speeds, so maybe that translates better into the sweet spot of the powerband?

What I really notice is that it revs higher before it starts moving. So, it feels more aggressive taking off. That might be the white clutch spring, too, though.

Top speed doesn't seem to be much different. WOT is 60-65 MPH on level ground and no headwind.

I'm seriously thinking of going back to the stock weights and clutch spring, 'cause I prefer a more relaxed power curve and less "grabby" acceleration.

Horses for courses...

Heavier weights spin out more quickly, because they are ... well ... heavier. So all of your pulley ratios will happen at lower RPMs. But you need the power at lower RPMs to do so. Lighter weights let the engine rev higher to spin the weights out, so same ratio, higher revs. It's great for smaller motors with less power for quicker takeoff.

At some point, though, you will achieve your highest ratio and then it's all up to RPMs for top speed, so the heavier weights get you there at lower RPMs, hence higher top end because your engine has more revs left.

The trick, especially in little bikes, is finding that sweet spot where you have a good power curve.

I tried all sorts of weights in my Aprilia 50 before I settled on some that gave me decent acceleration (I had a real dip in my throttle response right after takeoff that just a 1/2 gram weight change took care of) and left me enough for an acceptable top end. IIRC I settled on some 6.5g sliders.

I always ran 15-16g weights in my 150. It seemed to be the best balance between acceleration and top end. I mean, if you don't have decent top end on a 150, why bother?

I installed the Malossi kit to include the outer pulley, scooterpartsco.
Transformed the scooter, pulls hills like it never could. Better acceleration from a start if you want it or you could just putt around if that's your thing. Weights with the kit are 11.5. If you just want to change weights try 12.5 and nothing else.
I will never go back to the stock set up.

.....and your engine revs throughout your ground speed?

O.S.

Thanks. I appreciate your input!
I tried the DrPulleys in my Kymco - yep snappier take offs because they act like lighter rollers....but did not like the revs I was pulling at my customary ground speed of 30>35mph cruising.
I went slightly heavier on the DrP's and have stayed with that for years now. Figure my engine will last longer.

O.S.

No idea, higher than stock. Engine in a sweeter spot, doesn't sound like a sock in the intake struggling for air. I don't have to pin it down a hill in hopes of making it up the next without struggling. I live in a valley, the only way out is up and the Malossi kit helped with that. I don't give a rats ass about mpg either, it's less (I never measure mpg).
Someone would have to give me data that a lugged engine at low RPM's lasts longer than a less stressed at higher RPM's (again not a concern, rats ass thing).

Your riding requirements, fully understand.
I knew "lugging, lugged" would be along soon🙂
O.S.

I threw Dr. Pulley sliders in my Yager GT200i. Went slightly lighter on weights and it does rev higher. There was a method to my madness, though.

Manufacturer specifications for that scoot listed the torque peak at 6250RPM and the horsepower peak at 7000 RPM. Stock, it would rev to about 5200 RPM and then variate before accelerating to the torque peak. By lightening the weight and using sliders, I was able to get it to launch just under the torque peak and it would variate through to come out near the horsepower peak.

It made the scoot much nicer to ride in the hilly areas and a lot more fun to launch off traffic lights. It was also nice that the scoot had an analog tachometer that I could use to observe variator behavior during the tuning process.

As for revs, I'd worry more about fuel economy than engine wear. Pretty sure the Piaggio engine is better built than an LC GY6-B and I haven't been soft on mine. Redline starts at 8000 RPM but it's routinely been run at 9200 RPM for an hour or two on interstate trips up to Phoenix and back. 21K on the clock, no sparkle parties in the block, two valve adjustments (10K and 20K) and a regular diet of Motul 7100 with a new filter at each change. Still gonna send it.