Modern Vespa

Hello,

Anyone running with Dr Pulley Sliders Rolling on a GTS 300 ?
What weight ?

And also anyone experienced the HIT Clutch on a 300 ?
Is it worth on a stock engine ?

Using the following
J Costa Driver
HIT Clutch - (Dr Pulley) Just experimenting with various spring tensions
LEO V exhaust
waiting for Malossi Cylinder kit and will start toying with NOS

Yes...I want to embarrass a sport bike soon! since cruisers are getting boring

Nice!

I was hoping for more feedback on this product but not much info flying around on tech stuff. so I guess I'll get stock rollers for my scooter.

I have sliding weights on my 200 and it's been GREAT.

I went with 10g (stock is 11.5g) and saw a huge improvement in acceleration, reduced lag as the variator moves in better unison with engine RPM, and no loss in top speed.

The only downside is that now I get more clutch slippage. I'll probably upgrade that soon.

As the 300 has its torque and power peaks at lower revs than the 250, I would expect different weight rollers for them, and I would be surprised if the same J.Costa variator is correct for both.

Can any techo throw more light on this question?

Mike

It seems that not many people has made such mod on a GTS300.

For my little experience with automatic, the HIT Clutch should be a good fit for a LX125, to ease the take off (it's kinda slow), but on a 300 I find it very reactive.
What do others think ?

Sliding Rollers for GTS are available in increment of 0.5.
So witch way to go, lower or higher gramme ?

I would love to have the option on the 300 - there are some situations where you do want an extra bit of acceleration from a stop. Spending the extra cash however is always the sticking point for me - probably better to just get another scooter/MC for those times when you feel the need for speed.

I am still curious as well in regards to the 300... I have seen convincing arguments for both lighter and heavier Dr. Pulley sliders for the 300 in other threads but I have yet to see anyone report that they have actually installed them. I still don't even know what the original rollers weigh on a 300, there has been no response in my thread on 'original roller weights'.

The torque difference of a 300 compared with a 250 or 200 should make the rollers act differently, I just don't have the mechanical knowledge to determine what that difference would be.

I did order a set of 9.5 gr. Dr. Pulley weights but probably won't put them (or a combination with others) into my new scooter until spring after I finish painting it, so it will be awhile before I can test anything.

Desi B.

Voneschenbach, you might get what you want just by installing some Malossi clutch springs. Being stiffer, they allow the engine to rev a bit harder before the clutch takes. They come in a set of three grades, so you can choose a strength to suit you.

Mike

Read that original rollers for the 300 is 13,2

Read that Dr Pulleys should be 13-14,5 for the 300.

Read that original setup for the 300 is less tunable (less to gain) compared to the revvier 250.

But still not many comments to read about the 300 compared to the 250. Dont no why!

There have been quite a few discussions of that, actually.

Max (from Motorsport) weighed the stock 300 rollers and they were 13.9 grams. The curiosity question is, why would folks recommend putting HEAVIER Dr. Pulley rollers on a 300, and lighter ones on everything else?

To date, no one has chimed in saying they have done Dr. Pulley's on a 300...

Desi B.

I am also curious about the Dr, Pulley Sliders. I read somewhere that theoretically the heavier weights will give the 300 a little smoother acceleration and increase top end speed. That would work for me as I feel like I have oodles of torque or low end acceleration, way more than I need, but could use a little more top end for highway driving.

If this is true I will probably try the 14.5's this coming summer.

I really do not need any more power than the 300 offers.

MGG

Last edited by mgg on Sun Jan 31, 2010 12:22 pm; edited 1 time in total

The curiosity question is, why would folks recommend putting HEAVIER Dr. Pulley rollers on a 300, and lighter ones on everything else?

To date, no one has chimed in saying they have done Dr. Pulley's on a 300...

Desi B.[/quote]

I agree! I sent questiones to PM-tuning and to Polini. They admitted that as long as they dont do the same Dyno test as has been done with the 250 gts, all replyes are just theories. The one with the heavier weights is that the 300 does not gain in power when revved. The only obvious gain with a sport variator, again theory, is that the engine revvs intantly, giving stronger acceleration, but less smoth, in the low speed range.

From a 300 gts owner.
"The Poilni variator has made a massive difference. Nothing is holding the scooter back now - it just opens up and revs, and revs hard. Acceleration across the range has improved dramatically"

I went up 2 grams over stock with the Dr Pulley weights in My Malossi variator on my Zuma 125. I also used the stiffer spring that came with the Malossi. Bottom line it gave my bike a huge midrange and top end rush and netting me 3 mph top end while only hurting the take off performance of the scoot a hair.

That being said a Zuma 125 and GTS are like comparing apples to oranges.

One thing of note when using the Dr. Pulley Sliders is that the bike will perform much differently when getting off the throttle. When you roll off the throttle with the Dr Pulleys you can actually them move on the ramp and is much jerkier than the "roller" weights if this makes sense. It's not that huge of a deal but there is a difference in throttle "smoothness"

Polini sent me this graph of the Polini and the 300, showing more "intant" rev.

In SIP Scootershop Catalog, they state the Original Piaggio GTS300 rollers at 11g.

I have tried 13g Dr. Pulley slider weights in my 300, without changing anything else except for a 140 rear tire, and after nearly 1500 miles I have to say that I'm not thrilled with this setup. At first it seemed ok, but things loosened up after a little while and the performance has since taken a big hit. First, the engine revs up much higher than it should, so it's not even coming close to making use of all that great low-end torque that the 300 puts out. It seems like the variator isn't grabbing the belt nearly as well, probably due to the lighter weights (I'm assuming the original weights are 13.9g), and the clutch takes far too long to engage. In fact, when I was in SF for the Big Wet One, I seriously smoked the clutch going up the big hill on Divisadero - and I'm talking stinky, smelly, nasty asbestos smoke coming out of the belt case! And since the variator isn't grabbing the belt very well, I notice a very strong hot rubber smell whenever I park the bike.

Therefore, I think that 13g slider weights are not enough and heavier weights are needed. Those should allow the variator to exert more lateral force on the belt, which will grab the belt better and result in less slippage. Since the belt will be moving faster, the driven pulley will also move faster and engage the clutch sooner, resulting in less slippage there as well, which should deliver more torque to the rear wheel.

So my question is, where can I find heavier slider weights? The heaviest weights I see on scooter trap are 13g, although SIP has up to 13.5. However I'm concerned that those might not even be enough, and that 14g might be necessary. Does anyone know anyplace that sells those?

Also, has anyone else experimented with Dr. Pulley slider weights in a 300? I'd be curious to find out what weight they are and how the performance compares. I gotta fix this soon though, it's really bugging me since the 300 is my daily driver.

Hi,

As i know the original roller in Vespa GTS300 is 2117 in 13.8 gram,normally the SR is about 0.5 to 3 gm lighter than stock roller but the best weight for the SR 2117 may be various for different rider's requirement.
As for HiT201203 ( ie. for Piaggio group's 4t,125 to 300cc ),since its engagement is very solid,so clutch slippage is much less, you'll find its throttle response becomes very instant that is necessary and helpful to get excellent acceleration in whole speed range such as initial take-off , hillclimbing,overtaking or even the maneuverability at slow speed.

Normally the retail price is about USD300.00--350.00/set for HiT201203,45.00--50.00/set for SR2117 and DHL shipping 60.00.

I'd like to know is there someone who would pay 280.00 ( including DHL shipping to USA ) to get one HiT201203, 3 sets SR2117 in any weight but he should promise to post the REAL test result in this forum.

Sign me up Paul... you have my e-mail address I believe or you can PM me.

The only problem is my 300 won't be painted for another 3-4 weeks or so before I could put the stuff in and try it. Perhaps there are other MV users who could take advantage of your offer sooner and give us all some good feedback!

Desi B.

Desi;

Are you going to try both lighter and heavier weights?

I am curious as to if lighter gives more torque and heavier more top end with smoother acceleration or not.

MGG

I bought a set of the 8.5 gr. weights from scooter trap but from what I have been reading, I think that is far to light for the 300... (Plus I got the SR2017 instead of the SR2117 which will supposedly work, but I am guessing not as well...)

If I get more, I would like to try the 11 gr. and 13 gr. sets to see. Again, I am mostly speaking out of my butt based on things I've lernt on the interwebs... !

Unfortunately, I won't get a chance to try anything for well over a month, more likely two, so I hope others jump at Paul's offer direct from the manufacturer.

(In case anyone is wondering, Dr. Pulley appears to be legit, his name is Paul, and he has been helpful with information in the past on his products here on MV)

Desi B.

Desi;

Yes it would be at least two months before I could test as well here in WI. More likely 3 mo as our weather does not start getting good until April May. I hope someone jumps in and does some testing. Sounds like you really need the HIT to make things work well.

MGG

No thanks. But could you tell me if you make SR2117 weights in 14g?

There's no SR2117 14 gram in stock.
Are you sure you need the SR2117 in 14 gram ?

Like I mentioned before, I'm noticing a lot of belt slippage when accelerating anywhere in the lower RPM range, so I'm quite certain that my Vespa GTS 300 needs heavier weights. I'm concerned that 13.5g will not be heavy enough and that 14g might be necessary. However, if you don't make 14g weights, I may need to go back to using stock weights instead.

Hi,
If the belt is slippery then it's true you need heavier roller or harder torque spring to increase the clamp force.
i'll try to custom-made the SR2117 with weight heavier than 13.5 gm for you but you need to determine which weight is the best one among 14 gm, 14.5 gm or 15 gm to prevent the v-belt slippage .
The price of custom-made SR is 55.00/set and the shipping cost is 12.00 via air parcel ( ie. about two weeks ).

How about you consider my offer of "--280.00 ( including DHL shipping to USA ) to get one HiT201203, 3 sets SR2117 in any weight--" ? and you can sell the extra SR to other people, what do you think?

Hey Dr. Pulley... (aka Paul)

I suspect that if you can make a couple dozen heavier weight sliders for the GTS300 that you could sell them pretty easily to interested folks on MV. I know I would buy a set for sure to give them a shot...

Desi B.

Paul, I'm not interested in spending that much money on an aftermarket clutch when I have a perfectly good working clutch. I could change the springs in the stock clutch if needed, but so far that has not been necessary.

I have already bought three sets of your slider weights for my two GTS's; the 13g for my 300 which seem to be too light, a set of 10g for my 250 which seem to be too light, and a set of 11g to replace the 10g, which I have not installed yet.

However, I think I may have discovered a problem. I purchased these weights from scootertrap.com and they are 20x17, not 21x17 as you referenced. Your website does not specifically list the Vespa GTS 250 or GTS 300 for either size weight, it only lists Piaggio models, which are not necessarily the same as the Vespa models. Can you confirm that 21x17 would be the correct size for the GTS 250 and GTS 300? If so, can you tell me if this difference in size would result in the poor performance I have been experiencing?

Since the original roller for GTS250/300 is 20.9 x17 so the compatible SR is SR2117.
As for the difference i'll say the V-belt can move higher if the roller is the correct one, what do you think?

Hey Bagel,

I did the same thing (though I haven't installed my sliders yet). I think the 20X17s work, but not as well as the 21X17s that Paul recommends.

Desi B.

Paul, why are you asking me what I think? Your company designed and manufactures this product, I would expect that you would be the one to provide a thorough and definitive answer about its usage. I only have a basic idea of the physics involved in variator design, so I don't know how a small change in the size of a slider will affect the performance. Maybe a larger slider would make the belt ride higher; or maybe not, perhaps the lateral force exerted against the belt depends only on the weight of the slider. For that matter, I don't have any idea how the shape of the sliders differ between one size and another. For all I know, the angle of one face might be slightly different and that could have a more pronounced impact on overall performance than the length would.

I've already invested a great deal of time, money and labor in trying to figure out which of your products is the right one to use, but I can't seem to get a straight answer from anyone, including you. It certainly doesn't help that the vendors you sell to in the USA (e.g. scootertrap.com, ScooterWorks), are selling the wrong size for the GTS (20x17). Before I completely abandon your product out of complete and utter frustration, please tell me what the optimal weight would be for the following applications:

Vespa GTS 300 (stock): 20x17 13g is too light; what weight should be used for a 21x17 slider instead? 12g? 13g? 13.5g? 14g?
Vespa GTS 250 (stock): 20x17 10g is too light; what weight should be used for a 21x17 slider instead? 10g? 11g?

We are getting closer to an answer about weight, but someone will have to test them.
Looks like we (300 owners) need SR roller heavier than stock.

Hi,

I wish i could definitely tell which weight is the best one but it's really pretty hard.
Normally the scooter makers designing a fixed size ( ie. OD x height ) of weight roller for their CVT system such as variator to get a fixed Low Gear/High Gear value ( see the attached Fig. Curve of Full Load Acceleration), a fixed weight for their weight roller to get the best performance such as riding comfort, fuel milage, air pollution requirement etc.

So it's better to use the roller or SR in the same size.

If the roller size is changed then one or all original designed parameters such as Gear Ratio Value , the Shift Range and the slope of line b_c, line c_d or line d_e will be changed too.Then you need to do tuning to get the best performance for you.

As for the weight, people always use weaker contra spring for lighter roller used but some people still use the stock contra spring to get different results. The same, for heavier roller people always use hard contra spring but stock spring is also used to get different performance .

In Taiwan, the SR2117 used in BV250 normally is 10.5 gram with stock contra spring but some riders use 13 gram with harder spring.
We don't have GTS300 here but riders use SR2117 in 14 gram for
MP3 300 ( installed with HiT201203 ) with harder contra spring.
I do hope you could understand my explanation.

Curve of full load acceleration.pdf
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Are the weights really 21x17 or are they 20.9x17... that would help us tremendously. We have always sold the 20x17, mostly because the 21x17 were not available when we were ordering from the US distributor.

Matt C.

Hey Matt,

According to an e-mail I received from Paul a week ago, it is supposed to be the SR2117... This makes sense as I think a handful of people have said that the SR2017s seem to 'slip' a little after they have been installed for awhile.

Again - a disclaimer from me... I have NEVER installed these or used them, all of my info is heresay and conjecture based on info gathered mostly from MV, but I do have an interest in making sure I get the right ones installed when the time comes for me to do so.

Desi B.

I wonder what "slipping" means. They might clank a bit but it has to be better than getting ones that are too tight. I'll wait to see what Paul from UM says...

Matt C.

The 20 or 21 refers to the diameter of the rollers - installing 2017's merely mimics the 'Fuzzy washer'.

Well, I don't know what anyone else is referring to as "slipping", but what I'm talking about is belt slippage. When I accelerate, the engine revs up too way too high and it takes far too long for the variator to "grab" the belt. When I'm riding at speed, again the engine revs up when I try to accelerate. As a result, I'm smelling burnt rubber every time I park my bike and my gas mileage has gone down by at least 5 mpg since I installed the sliders. All this tells me that the 13g 20x17 weights are way too light for the GTS 300. However, I haven't been able to get a straight answer about what difference the diameter makes (20mm vs. 21mm), so I don't know how much of a factor the size of the slider plays in performance. I've also experienced similar performance with my GTS 250, which has 10g 20x17 weights.

Right now, I'm feeling very bitter about the fact that I have spent $135 of my hard earned cash on three sets of weights for my bikes, all 20x17, which were marketed as being the correct size for the GTS, only to find out now that they're all the wrong size...