Modern Vespa

Created article CVT Principles - How it works, how to improve it....

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Edited to change: to:

'To optimise the scooter's performance the engine needs to be running at its maximum torque output consistently while accelerating '

It might be worth adding that top speed is achieved when the maximum horsepower hits the limits of drag (friction and air resistance).

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Edited, to make changes to the terminology/wording after receiving suggestions from several Mvers.

Thank you all!!!

Fabio

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Have you edited the main index page to point to it? I note a few others of your excellent articles also can't be reached from the main page...

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Jim

I must admit I don't know how to do that??

I tried before but struggled a touch - I think its because the main index page is locked to me.

Can you point me in the right direction please if you would be so kind.

Fabio

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Edit the most likely pages where folk would look for such an article from the main menu, perhaps in the New User Frequently Asked Questions , and also in the Glossary of Terms (there is already a mention of Variator there).

If you think a new category needs to be added to the main page, just contact one of the Wiki Moderators - they should be able to help.

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I've had a look at the Wiki and I must admit that I find it hard to navigate (the layout of the sections and their contents I don't find too intuitive - I also find the search function hard to use - It produces many results but hides what you're really looking for in the masses of results that it generates - both of these are probably fine and the problem is more just down to how my brain works but I do recall reading threads where other users were saying similar things)

I was thinking that a new section could be created in the Wiki perhaps called "How to", would that be useful maybe? What do you think?

Fabio

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Perhaps a 'Tutorials' section as well - the problem is that many articles would be searched for by people coming from all sorts of positions - newbies looking for background stuff, oldies looking for an article to reference in some other post, or just looking for procedures or projects.

Perhaps the whole Wiki menu needs a re-think on the categories. Organisation isn't one of my strong points, so I'm stepping aside on this one!

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Yes I understand...

If a Wiki Moderator reads this then perhaps they can create for me a "How to/Tutorials" section, and then i can post my articles into that?

Fabio.

There are some pretty tough navigation/organization issues with the Wiki that probably continue to prohibit its use.

Your (excellent) article is so comprehensive, it fits into many places: Modifications, Routine Maintenance and some categories that don't yet exist.

I think many people just go to the "All Articles" page and look for what they need there. This is how I use the Wiki.

Personally, I'm not sure a "How To" section is right for this, because it's not a step-by-step tutorial as much as an explainer of what all these things are and what they do.

I'm wondering if we can create another category that may suit it better and encourage more articles like this. A "How Scooters Work" (or some such) category, maybe?

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Hi Eric

Yes this is the problem, when I'm trying to find articles on the wiki (or when using the site's search function for that matter) I never know where to start looking...

Of the articles I've written, I think most of them are based around a "How to" or "How it works", or the theory/principles of such.....

> Getting Your 2-Stroke to Run Properly
> 2-Stroke Carburetor Set-up Technique
> How to use a MULTIMETER to diagnose electrical problems.
> CVT Principles - How it works, how to improve it....

Perhaps we can have a category called "Theory/How it works/How to..." , or the such like?

Fabio

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I'm trying to add a new section to the wiki main page, but its locked??

How do I do unlock this??.... so that I can set up a section titled "Theory/How it works/How to..." , or the such like?

Fabio

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It's locked to prevent people from adding sections as they will.

The problem is, adding "Theory/How it works/How to..." will necessitate a lot of reorganization! I'm going to discuss with other Wiki mods and see if there's any agreement on a solution.

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That will be so brilliant of you!!

Thank you Eric.



Fabio

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Any further thoughts here?

Fabio

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It's been discussed but has sort of inspired a re-examination of the organization of that main page.

I think maybe a section called "Technical Reference and Fundamentals" might cover it.

I'll propose this and get back to you soon as I hear something. Thanks for your patience!

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Hi Eric,

"Technical Reference and Fundamentals" sounds fairly spot on to me!!

If you would like some ideas/thoughts/input into the re-organisation of the main page please shout up... I'd be glad to help!

Thanks once again

Fabio

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Okay, for now...

As there's already a Reference section, the article was placed there. We don't have enough of these encyclopedic "explainer" type of articles to create a separate section-yet. I would love to see more of these things, but understanding the workings of the CVT helped me immensely when I started doing maintenance on it.

I've got a 4T vs. 2T post I did elsewhere that will work well for this section. Articles on carbs and fuel injection, the electric system, etc. would be great, too.

So, keep up the good work. I'm going to add some of these to the Wiki wish list.

Also, one suggestion/request: Shorter slugs! We can't change them after the fact without causing havoc.

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Edited to include a Video link to youtube.

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Amended........ to explain about going too light with rollers weights, and the problem that it may lead to.

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No one has mentioned (I don't think) another reason for the "angled grooves" on which the rear pulley moves, Sometimes the rear pulley is refered to as a "torque drive". When you close the throttle the engine braking applies a pulling force to the bottom run of the drive belt. This pulls one side of the rear pulley along the angled grooves effectively forcing the pulley halves together. This reduces the effective "gear ratio", which stops the motor from bogging down when you want to pull away again.

Anyone can edit the articles, you know.

I have a question on this:
I think I understand how the whole thing works, BUT however one thing seems strange to me:
On main aim of the CVT is to keep the motor RPM constant at the best point.
but it need changes in rpm to alter the variator, right?
This means the front puley rpm remains constant (more or less), right?
But then I don't get how the weights are driven outwards.
Or is the front pulley rpm not equal to the engines rpm?

I thought rpm only changes at the rear pulley/ rear wheel.

Sorry for the confusion.

Amended...changed confusing terminology that I'd used between belt width and belt thickness

Amended....added a clarification note regarding removing the restrictor washer

What are the stock rollers in a Vespa 250 GTS made of? I presume all, including Dr. Pulleys, are synthetic... is that correct?

Also, are replacement "sliders", as opposed to rollers, more effective because they tend not to flatten out because the have the flat sides to begin with, so they simply stay in the trajectory of travel smoothly?

It is time to replace my rollers and I'd like to get a little more performance so Dr. Pulleys seem to be the answer, but... I am not quite sure why they add the performance, unless my assumption is correct. With mechanical things, I try not to act on my assumptions so an explanation would be greatly appreciated!...

Thanks for the awesome tutorial!

Most rollers that I've come across are made of a central "ring" of metal encased in a resin/plastic sleeve......

Like this--->



Sliders have more resin and are shaped like this--->



Watch here to see a good explanation...........

Excellent article clear and concise enjoyed reading the article and watching the video. I knew the basics of bike mechanics but was not sure how CVT worked now I know, really simple idea .I know its a few years old but just read it today.
Thanks for taking the time to post it.

You're very welcome.....

Edited the Wiki article to include information on Dr Pulley Sliders..............

I really enjoyed reading your article and find it very informative.
Although I'm an old timer with regards to performance vehicles, I'm new to the Vespa world and CVT/fuel injected scooters! My new '16 Primavera is awesome and although I only have 700 miles on it, I've done a few mods . I did the LED and turn signal pod removal mods (like Euro models) and some cosmetic mods and add-ons. Now, I'm ready for the Variator hop-up mod.

I already bought the tool, the Malossi 12.5g roller weights as well as the 9.5g Dr. Pulley sliders. I'm not quite sure on what to use but most write ups seem to favor the sliders instead of the rollers.

I also have not seen anything about dry hand-polishing the channels that the sliders move in. That, to me would make sense, wouldn't it? ...or is it a worthless effort for not much gain? I also read about the pros and cons of dry-lubricating the channels with some powder teflon stuff. They're on one side of an enclosed variator; away from the drive belt channel, so it should be OK?

Thanks again for all your informative help!

I've done some re-formatting of the article to use section tags instead of list tags, which are being phased out.

I've also updated the locations of several of the uploaded images, as they were being redirected from older locations.