Modern Vespa

what is the correct size for DR. PULLEY Slides (NOT SLIDERS) for vespa gts 300 with stock variator?
20x17 or 21x17?

sip scooter says that 20x17 fits to 250/300
http://www.sip-scootershop.com/en/products/slide+dr+pulley+20x17+sr+_sr2017n0
is it right (20x17 for 300)?

i'm confused as SLIDERS are 21x17...

Dear Sir:

Good day!! Thanks to your interest of our Dr.Pulley tuning parts. First, we are Dr.Pulley Corp in Taiwan. Meanwhile, regarding you inquiry for the roller of Vespa GTS300, could you send your questions to us via service3@unionmaterial.com. Eventually, we will also reply it to you asap after checked. Thank you!!

Best Regards

Daniel

The 20x17 is for the Quasar engine. The 19x17 is for the Leader, even though the GT takes a 20x17 roller weight. In the case of the slides, it's not a measurement of anything, just what they choose to call them.

The GTS rollers are 21x17 mm. The Polini variator takes 20x17 mm rollers. I don't recall what the Leader engine uses.

Fitting the slightly slimmer 20x17 rollers in a GTS variator has much the same effect as fitting a 1 mm spacer "fuzzy" washer in the variator - the belt would be able to ride a little deeper in the variator, giving a lower "low gear" and better take-off, but the belt might not get pushed all the way out at high revs, so that there is some loss in "top gear". Can't do any harm. Might be some roller rattle when idling.

Mike

My scoot is a 2010 Vespa 300GT and I weigh 220#'s.
I posed this question recently on one of the many! old & new "DR PULLEY" threads here on MV.
I came away from reading lots of posts in many threads thinking I might install the 21mm x 17mm x 14gram sliders.

I still have this question:
How does my weight play into the roller/slider choice for my machine? I don't care about "stop light derbies" so much as real riding down the highway-I am not an urban rider, I'm a retired, touring & occasional commuter on open highways.
I have no plan to change heads/cylinders/re-programing or much else beyond this DR PULLEY thing or an aftermarket exhaust or tire changes.
Ideas? THANKS!

I've just installed the Dr Pulley and a new belt (stock Piaggio) to my 2013 GTS at 9000 miles. WOW! Not only restored the smooth "new" operation of the variator but also gives a stronger and more smooth transition from idle to raid speed. Absolutely NO chatter, rattle, or shudder; just smooth and strong take-of and pull form idle plus the clutch stays engaged for better motor braking and engagement for a better riding experience.

I used the 21x17x13gr sliders and I couldn't be happier. Have put about 200 miles on since the maintenance/switch but this is a great option for this bike. If anything change, I'll post.

As to your question of weight (220#'s) no matter what you choose, physics can't be cheated but this set-up should enable you to feel not only a seat-of-the-pants improvement in acceleration, but also the same top speed as prior. I have also added a 140 size rear tire and this might also contribute to the top speed issue.

NOTE: It is not difficult to assemble the Dr Pulley sliders incorrectly! I suspect that this might be the source of some of the other posts' problems. Pay attention to detail, install them correctly and put the 1mm spacer BETWEEN the bushing and the outer sheave (not outside the sheave under the nut and other cup washer) and all will be fine.

Marklehnert- Thanks! A most helpful post.

Regarding the 1 mm spacer .. is this part of the stock variator?
Where is this an extra part that comes with the sliders?
I recently tried to install 10 gram sliders in my GTS 250...
The result was A delayed onset of rpm increase -
Seemed like it would wind up too late ..
Sort of like peddling to quickly going up a hill into lower gear

I installed 13gram sliders w/ stock belt. Huge improvement. extra spacer doesn,t come w/ sliders. only need extra spacer if running malossi belt. tends to rub case at top speed without spacer w/ M belt

Thanks for your reply-
Are you on a GTS 250?
Where are you seeing the improvement?
Faster take off?
Better top speed?
Thanks!