CVT - Is this black wheel necessary?
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Member
Piaggio MP3 400ie
Joined: 23 Aug 2019
Posts: 6
Location: Temeucla, CA
Fri Aug 23, 2019 6:58 pm quote
I wonder why Piaggio place that wheel between the variator and the clutch. I think it the couse of a slight buzz when the belt's lower lobs hitting it at some speeds. (mine at 50mph about). I do not see this thing on any CVT transmission like Honda, Yamaha etc. I'm considering removing it and wonder if anyone did that.

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Molto Verboso
GTS 250i.e.
Joined: 12 Jun 2008
Posts: 1356
Location: Sunshine Coast, Australia
Fri Aug 23, 2019 7:09 pm quote
Thats the belt support roller. It stops the belt hitting the belt, kinda necessary.
Member
Piaggio MP3 400ie
Joined: 23 Aug 2019
Posts: 6
Location: Temeucla, CA
Fri Aug 23, 2019 7:18 pm quote
GTdespatchcourier wrote:
Thats the belt support roller. It stops the belt hitting the belt, kinda necessary.
Belt hitting the belt? Do you meant something else? I do not see what the belt will hit and which belt. Like I said, this wheel is not installed on any Japanese or Korean scooters.

Screen Shot 2019-08-23 at 8.19.50 PM.jpg
Here a mix of may CVT scooters whit no one have that thing

Molto Verboso
GTS 250i.e.
Joined: 12 Jun 2008
Posts: 1356
Location: Sunshine Coast, Australia
Fri Aug 23, 2019 9:57 pm quote
When you come off the throttle there is a chance the belt will come into contact with itself, supposedly.
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 37598
Location: Pleasant Hill, CA
Sat Aug 24, 2019 7:32 am quote
Not just supposedly! When coming off the throttle at full speed, the clutch stays engaged with the belt fully inside the driven pulleys, and the belt can fall to the inside of the variator and driving pulley. With both radii at minimum, the belt can very easily catch against itself - doing damage to the inside teeth.

Remove the idler pulley at your peril. If it 'whirrs' then replace it (easier then just replacing the bearing).
Member
Piaggio MP3 400ie
Joined: 23 Aug 2019
Posts: 6
Location: Temeucla, CA
Sat Aug 24, 2019 9:48 pm quote
jimc wrote:
Not just supposedly! When coming off the throttle at full speed, the clutch stays engaged with the belt fully inside the driven pulleys, and the belt can fall to the inside of the variator and driving pulley. With both radii at minimum, the belt can very easily catch against itself - doing damage to the inside teeth.

Remove the idler pulley at your peril. If it 'whirrs' then replace it (easier then just replacing the bearing).
I understand your point, but no other scooter cary this thing. Search and see. Kymco, Honda, Suzuki, Yamaha. None have that and most have longer belt life for some reason.
Hooked
Gilera Fuoco
Joined: 17 Sep 2017
Posts: 112
Location: Birmingham, England
Sat Aug 24, 2019 11:45 pm quote
Maybe other brands address the problem of 'Belt Whip' by some other means - but my reasoning is that if just 10 cents could be saved by leaving the idler pulley out of the design, then they would have done so.

If you closely examine the circumference of the idler, you will probably see where it has been contacted occasionally by the teeth of the belt.

No doubt the outer edge of the belt will also contact the inner surface of the casing during 'Belt Whip', but this is nowhere near as bad as the teeth hitting each other whilst moving at high-speed in opposite directions!

Some of those pictures above do seem to have something in the middle of the belt run (other than an idler pulley) to stop the teeth contacting each other during Belt Whip, but as an engineer I can appreciate why a pulley would be a better solution.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 7494
Location: Ashburn, Va. Home to the Internet
Sun Aug 25, 2019 4:52 am quote
Duboiz wrote:
jimc wrote:
Not just supposedly! When coming off the throttle at full speed, the clutch stays engaged with the belt fully inside the driven pulleys, and the belt can fall to the inside of the variator and driving pulley. With both radii at minimum, the belt can very easily catch against itself - doing damage to the inside teeth.

Remove the idler pulley at your peril. If it 'whirrs' then replace it (easier then just replacing the bearing).
I understand your point, but no other scooter cary this thing. Search and see. Kymco, Honda, Suzuki, Yamaha. None have that and most have longer belt life for some reason.
The manufacture didn't put it there because their cousin Tony had a dozen to sell, there is a reason it is there whether other scooters have it or not.
Replace the pulley or replace the bearing in the pulley.
Molto Verboso
GTV300 (wife's)
Joined: 08 Nov 2014
Posts: 1172
Location: Central New York
Sun Aug 25, 2019 5:03 am quote
I guess if you really want to try running with out that idler I would wait till its getting close to new belt time and remove it and go for some rides near to home.

That way if it does cause a problem you won't have to push the bike too far!

That said I think that is the same design as say my wife's GTV and don't recall her mentioning any "buzzing sounds". I know the time I have rode her GTV I never noticed anything, but then I usually ride a Sportster or XS650 Yamaha so any thing else is smooth and quite to me!
Hooked
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 441
Location: tampa
Sun Aug 25, 2019 7:27 am quote
I bet the original poster is STILL wondering why piaggio engineers put that pulley there.

I do agree with WEB-tech statement.

there are plenty of videos of the CVT running through the gear ranges. from those videos I would say the belt can never slap so much during normal operation to contact itself. or even slap enough to need the center pulley. however what I would like to know is what happens when someone locks the rear brake at speed. that is the only situation where the pulley is likely doing something valuable. is someone finds a video of that post it up.
Member
Piaggio MP3 400ie
Joined: 23 Aug 2019
Posts: 6
Location: Temeucla, CA
Sun Aug 25, 2019 9:02 am quote
Some of those pictures above do seem to have something in the middle of the belt run (other than an idler pulley) to stop the teeth contacting each other during Belt Whip, but as an engineer I can appreciate why a pulley would be a better solution.[/quote]

Those are manual kickstart unit. Nothing to do with the belt
Member
Piaggio MP3 400ie
Joined: 23 Aug 2019
Posts: 6
Location: Temeucla, CA
Sun Aug 25, 2019 9:06 am quote
jerryd wrote:
I bet the original poster is STILL wondering why piaggio engineers put that pulley there.

I do agree with WEB-tech statement.

there are plenty of videos of the CVT running through the gear ranges. from those videos I would say the belt can never slap so much during normal operation to contact itself. or even slap enough to need the center pulley. however what I would like to know is what happens when someone locks the rear brake at speed. that is the only situation where the pulley is likely doing something valuable. is someone finds a video of that post it up.
When you lock the rear wheel the bell is locked, but the clutch is fee to spin with the engine. It will be a total failure if not with or without the black wheel.
Hooked
2019 MP3 hpe 500 sport Advanced " Missy "
Joined: 21 Dec 2018
Posts: 249
Location: West Germany
Fri Aug 30, 2019 12:50 pm quote
Hello fellow impies. If do say so myself, some of those belts look shorter than the mp3 Belt and the longer something is the more flexible it is. That is possibly why the pulley is there .
Enthusiast
mp3 500 2016
Joined: 30 Dec 2011
Posts: 73
Location: singapore
Sat Aug 31, 2019 6:15 pm quote
Just leave it there.it not much weight anyway.
Hooked
2019 MP3 500hpe Sport
Joined: 03 Nov 2014
Posts: 454
Location: Germany
Sun Sep 01, 2019 9:20 am quote
although manufactures do install stuff that is not needed in my opinion, i do think that this roller should be there based on what others have said. besides...weight savings of a pound or two is not worth the test.
Ossessionato
BV350, Primavera 150, Yamaha Zuma 125
Joined: 06 Jun 2013
Posts: 2842
Location: The Twin Cities of Minneapolis/Saint Paul, Minnesota
Sun Sep 01, 2019 10:00 am quote
Duboiz wrote:
Some of those pictures above do seem to have something in the middle of the belt run (other than an idler pulley) to stop the teeth contacting each other during Belt Whip, but as an engineer I can appreciate why a pulley would be a better solution.
Those are manual kickstart unit. Nothing to do with the belt[/quote]
Perhaps the kickstart bolt also serves the purpose of keeping the belt separated. If there is no kickstart then maybe a simple peg works as long as there isn't much friction there. Also, could there be a separating piece in the outside half of the belt case?
Veni, Vidi, Posti
Modded Vespa 2017 GTV 300, BMW 2017 C650GT, Ural 2019 Gear Up
Joined: 21 May 2017
Posts: 5617
Location: Downtown Toronto
Sun Sep 01, 2019 12:00 pm quote
Like others have said. Why the hell would you even think about removing a part that the manufacturer put in to an important part of the bike that has the bits that make the thing move? Damn that just sounds dangerous to me and something that can win you a Darwin Award. It might not be done by many or any other CVT PTW manufacturer but it's also not the same engine. I get that maybe it annoys you but the answer there would be buy a bike that doesn't have it/
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 2215
Location: Starfleet Command, South Eastern UK HQ
Sat Sep 14, 2019 2:56 am quote
Well on the GTS bikes it has the same type of pulley, and it works! The pulley on mine has marks on it that indicates the belt is coming into contact with the pulley. From what you say, the noise on yours is being caused by your belt coming into contact with your pulley too. This shows the pulley is working. It's essential. Many CVT transmissions have this type of system.

Strongly recommend you don't remove this pulley because you will get trouble if you do. You don't have to take my word for it, just remove it and you'll soon see what happens!
Hooked
2019 MP3 hpe 500 sport Advanced " Missy "
Joined: 21 Dec 2018
Posts: 249
Location: West Germany
Sat Sep 14, 2019 8:19 am quote
Stromrider wrote:
Well on the GTS bikes it has the same type of pulley, and it works! The pulley on mine has marks on it that indicates the belt is coming into contact with the pulley. From what you say, the noise on yours is being caused by your belt coming into contact with your pulley too. This shows the pulley is working. It's essential. Many CVT transmissions have this type of system.

Strongly recommend you don't remove this pulley because you will get trouble if you do. You don't have to take my word for it, just remove it and you'll soon see what happens!
Amen! Brother Starfleet Engineer
Hooked
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 441
Location: tampa
Sun Oct 13, 2019 5:31 am quote
Hooked
2016 MP3 500cc Sport ABS
Joined: 01 Dec 2009
Posts: 302
Location: Lombard, Il
Tue Oct 15, 2019 11:49 am quote
From what I see on this video it's function is to limit the play of the belt that can really oscillate a lot.
At the same time it explains this vibration/noise you have sometimes around 20-30 mph on the 500cc... the belt hitting the free wheel.
Veni, Vidi, Posti
Neutrino MP3 492.7 AK, 2013 Moto Guzzi Norge
Joined: 29 Mar 2008
Posts: 21405
Location: Harriman, Tennessee, Tn
Tue Oct 15, 2019 12:51 pm quote
piaggio had a special deal from the manufacture on all those idler wheels so they just threw them in a bunch of scooters, no real reason just cause.
Ossessionato
2016 MP3/500 Sport ABS, 2009 MP3/250, 2012 GTS Super 300ie
Joined: 08 Jul 2011
Posts: 4227
Location: Marietta, GA
Fri Oct 18, 2019 5:57 am quote
Remove it and let us know?
Maybe worth a few bucks on ebay.

I know of one person here on MV that had to replace his, so my guess it does get some use.

Keith,
Marietta, GA
Team Scooter Trash for Petfinder Foundation   Vespa Wasp Pin Badges   Scooter Parts Company
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