Modern Vespa

Hey All,

I want to put 12g Dr. Pulley sliders into my GTS 300. (21x17)
Someone told me that inorder to avoid the potential problem of the belt springing a leak in the oil pan I need to swap out the stock belt for an GT200 belt. I've never heard of this approach before. I've heard of the fuzzy washer solution (and I've also heard of just adding the sliders without any other modifications).
Any thoughts on this?
Thanks

I am not sure what you are looking for, but sticking with standard Piaggio rollers, including the weight of each, and using an OEM belt (Malossi is fine too) you will not go wrong.

I have found no speed or durability improvement by using sliders or other weights in the rollers.

I have run sliders twice. Both times I ended up with broken variators.

I ride harder than most.

I appreciate your input however my experiences have been the opposite of yours. On my 2010 GTS I did a lot of experimentation and by FAR the best combination I found was with the stock variatior and Dr. Pulleys. Compared to stock rollers the bike ran much more smoothly at idle, and had better and more consistent acceleration.

Can anyone verify any benefit in putting a GT200 belt instead of the stock belt in the GTS 300 when combined with Dr. Pulley sliders?

Thanks

Then the sliders were either to heavy, or put in wrong.
If you had the correct sliders you will most definitely feel a difference.

Any thoughts on using a GT200 belt to counteract over extending the belt and eating a hole into the oil pan??

They were purchased from two different advertisers on this site, weights as they recommended and installed by the one of the best mechanics in the country.
I am simply sharing my very real experience.
I too liked the quieter idle and smooth acceleration. But no faster top speed or better acceleration than standard rollers.

As for using a GT belt on a GTS, they are different lengths for a reason.

I feel like your comment isn't based on real world experience but rather speculation--which is fine. The fact that they ARE slightly different lengths is the reason this was recommended to me (by a mechanic who only works on Vespas btw)
I'm just wondering if someone with actual real world knowledge of this belt substitution can chime in...

I put Dr Pulley sliders in a few weeks ago, and a new standard OEM belt. Within a couple of days the 6 year old, 32,000 mile oil pan gasket had been torn. I replaced the gasket - and the new gasket *doesn't* protrude from the join between oil pan and transmission case. Now all good.

Whether this was just coincidence, or the new gaskets have a slightly different profile, I don't know.

Personally, I'd keep the 300 belt as its outer teeth help a lot with cooling, and I ride hard.

Jim, I have never heard of sliders causing a gasket failure before, but I had a similar experience with my new GTS300. I installed the Pollini variator that I had had in my GTS250 for many years, and the belt promptly shredded the gasket. Must be something funny about the gaskets on the new scooters.

So I am now using sliders - 13 grams.

Fitting a GT200 belt will slightly reduce the range of the transmission, the reverse effect to fitting sliders, so the two will cancel each other out to some extent. A better option if the sliders are going to cause rubbing, is a thicker washer inside the variator. An extra 0.5 mm will keep the variator halves a bit further apart and prevent the belt riding so high.

Mikje

Thanks Mike:)

And the reason for doing all of this rather than running stock components is........

Man no offense, but there a lot of threads that you can read and chime in on here on the forums. Maybe if you don't mind just move along. If you don't appreciate the value and enjoyment that certain people get from specific aftermarket upgrades and tinkering then you just don't get it. And that's your prerogative. But don't condescend on people who do.

Mr Leuthold, you have obviously never ridden a kitted GTS.

Aftermarket shocks can make a big difference to the handling. A Malossi V4 cylinder and head can make a very big improvement to the performance. Aftermarket variators and/or sliders can improve take-off and top speed. Brembo calipers can improve braking.

Please don't come back with the retort "Why don't you buy a bigger bike then?". We like Vespas and we enjoy fiddling with them. The GTS is not designed for performance. The same exhaust, air filter, cylinder head and transmission are used on the 125, 250 and 300, the only differences being a new camshaft and heavier rollers in the 300. The engines are designed for economy and European emission guidelines. Compare the GTS power/capacity with the BV350 power/capacity and you will see how under-tuned the GTS is.

Mike

So if sliders are such a vast improvement over rollers, why don't any of the big performance companies or race teams use them? They were around in Italy for at least twenty years before Dr. Pulley invented them. Why is it only people on english language websites who don't know what belt to use wax so poetic about them? I have heard that when people race motor vehicles, the intention is to win, and if sliders offer the advantage the tuning experts who have chimed in so far believe they do, why aren't they one, two, three on the podium every race day?
Inquiring minds want to know.
It was probably Zelioni who first came up with the idea of using the GT belt in the GTS, which is not surprising, because everyone knows they are the scooter tuning experts. And their stuff is pretty too. . The best way to find out what belt works best for you is sort of like the best way to find out what toilet paper you like. Give it a try and see how it feels. Usually scooter tuners go for a longer belt, but if the collective brain trust on your race team thinks shorter is better, see if they're right.

I didn't know any race vehicles used variators! I thought they were all manual gear-change, or else electronic gear-shifting. Can you name a single racing car or motorcycle that uses a variator?

I'm sure I heard recently that some of the larger scooters now come out with sliders as standard, but I cannot recall which (I think BMW).

As for English language websites, go and look at the German and Austrian Vespa forums. That crowd are deeply into Vespa tuning, even machining their own camshafts. I just did a search for Dr Pulley on Vespaforum.de, and got 161 pages of hits. So you obviously don't know what you are talking about!!!

I have been visiting Modernvespa, GTSowners, Vespaforum.de and Vesopaforum.at for many years, and have never ever seen anything about using a longer belt than standard. The correct length for a belt is when it just reaches the top of the variator when it is at its deepest in the clutch pulley. If it is longer, it will rub on the housing (certainly with a GTS!). and if it is shorter the full range of the variator will not be achieved.

Mike

Calm down guys. We're on a friendly Vespa site, not BMW!

I am well aware of the limitations of the Vespa engineering on these engines. Clearly, improving the breathing will improve performance significantly. My comments were regarding the transmission only, and changes here simply can not significantly overcome lack of horsepower and drag.

I have found, through many miles of riding hard, that the biggest improvement, in transmission changes, I have seen is in replacing the belt, usually good for a few mph. After running many options in sliders and rollers, again through many miles of experience, I have settled on the OEM Piaggio 10.7g rollers. With these, along with a new Malossi belt and 140 rear tire (to slightly improve gearing) I can hit up to 85 mph in perfect conditions of downhill, downwind, in a draft, in a tuck, on any of my 3 GT's.

As for riding a kitted GTS, no I have not ridden one. But I have ridden a completely tricked out GT. Malossi 218 cylinder, piston, head, variator etc. It was fast.

But two weeks ago I rode in to Mukilteo after completing this year's Cannonball Run 2 hours and 20 minutes ahead of it, with a third place finish in the official standings while having the fastest raw time among the 35 competitors.

As for the motorcycle comment, I have a Honda NC700X (manual version), that stays in the garage while I put 15,000+ miles a year on my three Vespa GT's.

My comments were to offer my real world experience to help you.

What do you think an over-range transmission is?

Here's a video of people who appear to be racing on vehicles with CVT transmissions that use variators. But they might just be celebrating "paint your bike to match mine and go around this track as fast as you can" day. I'm going to go out on a limb and say they are probably racing.
There's this guy named Valentino Rossi who does something with motorcycle racing, I'm not quite sure what, who started racing scooters with CVTs and variators.

And here are even more people who appear to indeed be racing scooters with variators.

See how many Dr. Pulley stickers you spot.

I agree with this. I don't enjoy putting more wear on the crankshaft threads by "tuning" when Piaggio got it right from the beginning.

EDIT: In addition, it's always hard arguing with the tuning enthusiasts because everything is done by feel, not science. Like the person who said sliders run smoother.. it doesn't work like that. The brain is a funny thing.

You're not exactly quoting any science of your own by simply saying 'It doesn't work like that'.
There are plenty accounts of riders claiming that their experience of using sliders has resulted in a smoother ride. Whether or not this is science doesn't matter to me. Real world experience is more important to me. I know my experience with sliders has been positive. The ride for me has been better. Period. I don't need to justify it to anyone.
That being said, I'm not a mechanic do always welcome technical advice if I'm going to add anything that is aftermarket.

It's not easy to tell whether a variator has Dr Pulleys in or standard rollers - if the rollers are new. As soon as one or more has flats on it, the difference becomes apparent at idle. If you do a lot of urban stop-start riding, the Dr Pulleys stay smooth right up until they're worn out - minimal rattle.

At any sort of speed, I don't know how you'd tell the difference (except of course that due to different weights etc).

I just got my 2016 GTS 300 super a week ago, and right from the beginning the variatior has sounded like a Yatzee cup full of dice at idle.

Motovista, Malossi's over-range transmission involves fitting a larger diameter variator pulley to allow the longer belt to ride higher. Try this in a GTS transmission and you will have the belt rubbing and destroying the crankcase gasket. I googled it but couldn't find any reference to Malossi's kit in relation to a GTS - I wonder why?

Of course racing scooters don't use sliders. Nobody ever claimed that sliders gave more performance than aftermarket variators. But they come close, and are by far the best bang for buck. Besides, racers don't give a damn about durability as they usually rebuild their engines before every race. To them, durability means lasting to the end of the race.

Mike

Not sure you will ever get "science" in a public forum on scoter variations. the empirical evidence provided by JimC would be the most applicable to the original question and the problem encountered was resolved with a new gasket and the problem has not shown up again.

The problem of the belt rubbing and ripping out the gasket (GTS250-300) has been seen mostly with aftermarket variators that have more range or push the belt higher in the pulley than stock. This does give a higher top speed by a bit but does risk rubbing. The stock piaggio rollers are actually 20.9x17 while the sliders are 21x17 (you could sand the flat to bring them to 20.9), so that slight increase combined with a fresh belt and a gasket that protrudes into the path of the belt could be the cause of the gasket failure in that one case. With other variators that commonly have the rubbing issue, the mitigating action to make the gasket last longer is to trim off any excess that sticks up into the belt case.

The GTS 300 will max out the variator at ~68mph with the engine at ~7500rpm. Above that speed the engine spins faster but power will continue to fall off. Since there is not much room in GTS to allow the belt to ride higher in the variator, there is not much you can do to the variator to impact performance above 68mph.

Changing the gearing on the other hand can shift the working range of the variator up to 76mph but doing so makes the variator more sensitive to the weight of the rollers/sliders, so more care must be taken to get the weight just right. This is at the expense of the 0-20mph performance.

Nice sum up!

Mike

The shorter than stock belt is a pretty common tuning fix for the GTS. As I said earlier, Zelioni recommends it with their variator, and Polini has a belt that is quite a bit shorter than the stock belt, and another belt that is even shorter than that which they use in their special transmission.
It's not going to hurt anything to put in a GT200 belt, and it's about 10mm shorter. The Polini belts are a whole lot shorter, or they measure things differently than everyone else.
Give it a try and see what it does.

I have been riding Rocket a lot recently, since it is the only GT I have at home that is working these days. It has 71,500 miles on it. Recently, the acceleration has been weak in the mid range of 15 to 45 mph. I blamed this on putting heavy (12g) rollers in when changing a belt a year ago.

Yesterday, I took all of the transmission parts out of a spare engine and transmission I bought recently and installed them on Rocket.

These are all stock parts off of a 2005 Vespa GT that had 5000 miles on it when crashed. These included the variator, outer drive pulley, toothed starter ring, black roller, clutch, clutch bell and bendix. I also used the entire cover as the old one had been damaged by a loose variator nut twice.

Into the stock Variator I installed six 10g Dr. Pulley rollers (not sliders) that I had in my spare parts drawer.

After doing this, the hole in the acceleration was gone as revs stayed high during these speeds and the top speed increased by a few mph.

I was quite pleased with the performance.

What belt are you using Bill? The OEM GT200 belt doesn't have outer teeth...

every one I've seen does. The LX belt does not.

I have run the LX belt in a GTS 250 with the polini variator to prevent the case rubbing issue, but that was for racing where longevity was not really tested.

Interesting - I was sure my UK GT200 belt doesn't have outer teeth - but you've convinced me I am confusing them with my memories of other belts.

I have a Zelioni variator and use the standard GT200 belt in my GTS300. According to Zelioni, it is necessary to prevent the belt from rubbing holes through the case or whatever. So I use the standard Piaggio Gt200 belt. No issues, awesome acceleration, slight increase in top speed. My scooter has 14000 miles on it, 7000 of those are with the Zelioni set up. I see no reason to go back to stock ever.

Jim, that is a Malossi belt going into the scooter. but the belt I took off the spare engine was probably an OEM belt. It had teeth on the back.

I used Piaggio belts for years and they all had teeth on the outside.

I have had good service with the Malossi belts and, with the cost savings, will continue to use them.

Hi Jim, i concur all the gt200 belts i have bought here in the uk are without ribs, my favorite is the dayco 814mm OEM top quality at a good price.
Cheers Andy.

814mm is the length of the stock and many aftermarket belts for the air cooled leader. The Dayco belt for the GT200 does have ribs on both sides, and the last one I bought was 826mm, if I remember correctly, two mm longer than the new Malossi belt. II think the early 180 LC leader engine in the Runner, Hexagon, etc, may have come with a belt with ribs on only one side, but I've never seen a belt designated by the manufacturer for the GT200 that didn't have them on both sides. The GT belt is usually 824-827mm, and the Quasar belt is in the 834-835mm range, so going to the GT belt in the GTS is not a big change from the stock length.

10 years ago we seen aftermarket belts for GT200 without the outer teeth.
You may recall these.