Modern Vespa

Hi everyone, I'd like to raise few questions.. please don't judge me. I know this is endless and a keep repeating discussion.

The problem I have is, recently, I feel like my Vespa wants me to ride it like a racer. It is when my scooter take off so quickly right after I pull the gas. I know some people love this style of riding, but not for me. I want my Vespa to be smooth at take off and smooth at getting the top speed. That's all.

So, in this case, will stiffer (higher rpm) contra spring give me the desired smoothness?

I'm so confused with the informations available. Some said that stiffer contra spring will make the scooter accelerate quicker, but it doesn't sound right to me because I imagine stiffer contra spring will take a higher rpm or few more seconds to be pressed and let the belt to get to the inner of the rear pulley, compared to softer contra spring.

I'm also confused when some people told me that I should use lighter roller when changing to a stiffer contra spring.

Will stock roller (15.5 gram), 1500rpm Contra Spring, and 1500rpm Clutch Spring get me to the desired results?

Good problem

Sorry can't help but I'd bet those that can will need to know,

Is your current set up, rollers, contra spring, gearing, exhaust and everything else stock?

I have a Primavera 150 3 valve and Sprint 150 3 valve, from what I understand and feel, the Sprint is geared to take off faster but the Primavera is geared for a higher top speed, I put lighter rollers in both to theoretically make them faster off the line.

following: smooth starting at smooth acceleration to top speed is my preferences also, my daredevil days are well in my past.

Yup, everything on my Vespa CVT and engine are stock. I did not modify anything related to engine specification.

Keep a tiny bit of rear brake on when you first start moving - that prevents any jerkiness when taking off. Release when you're moving and modulate the throttle gently, it isn't a switch!

Be prepared to replace rear brake pads a bit more frequently though.

This trail braking when taking off contributes to very smooth riding.

That's the problem. I hate it when I have to open the throttle too little by little, u know… and I feel like keeping a tiny bit of brake during take off still make my Vespa jump even soon after I release the brake slowly.

When I had 2 BV's, I was able to compare stock to performance parts. I was very happy with the upgrades.
Now I have two Honda's. I was not happy with performance parts on the 150. The side by side comparison of the Malossi vairator and stock showed little improvement. Running at higher RPM's was annoying and MPG suffered big. The clutch glazed up and started slipping after only 500 miles.
I replaced the stock Variator but kept the white contra spring in. The white spring has a stronger launch and it doesn't affect top speed. I'm happy with the white spring as my only performance upgrade and I have accepted that I need to feather the throttle on starts.
WAG, It seems that less HP = less improvement from performance upgrades. More HP = more improvement. IMHO if you want more from your 150, trade it in on a 300.

The heavier clutch springs will make the engine rev higher before the clutch engages. so if you don't like how it takes off now, you are really going to be unhappy with the new springs. The Contra spring works against the Variator rollers in order to keep the belt low on the variator face. A heavier spring will keep the belt lower through a higher RPM range, so the bike accelerates while the engine is making the most power. If you think the stock 150cc 3V Vespa has too much acceleration, you can put in even heavier rollers. That will slow it right down. If you go to something like a 21 gram weight, you'll probably have to walk very fast to keep up with it.

Turns out I've been using 12g sliders for the past 2-3years. I guess it was the mechanic idea to put the 12g without consulting to me, since I believe Vespa Sprint 3V iget 150cc is originally manufactured with 15g sliders. I remember that 2 or 3 years ago they told me that I need to replace my stock sliders, but I didn't know they put the 12g instead of 15g (yea.., I know nothing about motorcycle at that time). Probably because they didn't have the stock at the moment because yesterday, I had a visit to Vespa workshop when I found the culprit (12g sliders), and they didn't even have the 15g on their stocks for quite a long time when I asked for it. Many in my city demand for 12g, and that's why they don't get the 15g sliders on their display.

Btw, you are right about all. I didn't like the new contra and clutch spring even more. I can understand now how both springs perform. It feels heavier to reach higher KmH or MpH with stiffer contra spring, and stiffer clutch spring even make my vespa take off more surprisingly like a jerk. Even it is getting more undesiring to open the gas slowly with the new clutch spring.

Next workshop visit, I will reuse the stock clutch spring to replace the current 1500rpm, and will try looking for heavier roller weight. I just found that Dr.Pulley have 15.5g Round Roller for my Vespa, even at a cheaper price and better quality (they claimed), but ofcourse will try replacing the roller only first. If it didn't work out in making a smooth take off, I guess I will bring everything back to original specification, for both sliders, clutch spring, and the contra spring. Since it is not only the way it take off who bothers me, but the fuel consumption also increase quite drastically (±33KmL to ±27KmL). I didn't regret the decision to use the racing parts, cause that is the only way I could know how different specification parts perfom. Trial and error!

My question now, would it be okay to use 1500rpm contra spring with stock clutch spring (which I don't know how many rpm it is)? I mean, they have different rpm ratings, so would it be a problem?

Hello,

Yes the contra spring has nothing to do with takeoff, it's purpose is to keep the belt down in the variator for a set amount of time. They really aren't rated at 1000, 1500 or 2000 rpm. Someone started doing that, and it stuck.
They are rated by how much force it takes to compress them, and then what percentage increase or decrease that is from stock.
Put the 15 gram rollers in and you will be able to figure out why they went to 12 grams. 13 is probably perfect, but go with rollers, not sliders.

Listen to this person he know's more than Robot!

My wife had this issue on her Primavera and I took it for a wee ride. I found no free play in the throttle, basically it went from nothing to on instantly (a bit of a crude description). I adjusted the throttle cable slightly to give a little free play as recommended and her take offs changed instantly. Happy wife - happy life.

Yeah I just read some post and articles about contra spring, some brand put percentage of the stiffness as rating and others put rpm. Although it is wrong to use rpm rating, it just quite make sense especially for beginners to understand the different stiffness in aftermarket contra spring. And I thought slider and roller refer to the same thing. I read people's post about roller and they use the two terms interchangeably. Yeah I will stick with round roller first.

About my previous question, I guess it would be ok to keep using the stiffer contra spring and using the stock clutch spring r8? The downside is that the v belt or drive belt wear a lot quicker compared when using the stock contra spring.

You did it by making adjusment on the throttle cable right? I did that too before changing the springs, but it still didn't give me the smooth take off and acceleration that I want. Anyway, thanks for the input.

No doubt!!

Did I fix that for you, or am I wrong?

I know my Honda's are different(15.5 HP vs 12-13 HP) than Vespa's. The black bike is stock. After reading this thread I've been testing takeoff and am unable to stop the lurch on take off. Might be flat spots on the rollers. I'm changing the belt and rollers next week so I'll have something to compare to.
My red bike has the Malossi variator and because of clutch glazing, stock 12.5 rollers. It has the white contra spring installed. I can feather the throttle for a smooth take off and the clutch isn't slipping after 2,000 miles. The Malossi variator has a different geometry than stock, so I can't claim the improvement is only the contra spring.

The contra spring works to counter (contra, against) the effect of the variator on the belt and does what we both said it does. Two ways of getting to the same place.

Update
Roller: Dr. Pulley 15.5g Round Roller
Contra Spring: Kawahara 1500rpm (I know what you're thinking)
Clutch Spring: Kawahara 1500rpm
Feeling: I have never been as happy as I am today since I installed the current setup.

Both takeoff and acceleration are smoother compared to previous setup. The engine doesn't sound as noisy as before, and I feel like the power produced by the engine are transferred proportionally through each step.