2007 BV250 Variator Fix correction
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Hooked
GTS 250ie Super, BV250, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 363
Location: Winston-Salem, NC
Sat Jun 23, 2018 2:51 pm quote
I have 2007 carbed BV250 that I have been putting back together. the last step was the CVT. On My GTS i run sliders and a Malossi belt on the stock variator and clutch and like the way it rides so I went ahead and did the same. When I opened the CVT the belt was high on the variator and down on the clutch and with the new parts it was the same. I took it for a ride and it was straining a bit until I got to about 20mph. I was done for the day so I didn't go further without a plan. So I thought on it last night and it hit me. Of course it was straining to start moving I was starting in second or maybe third gear. It needed a bigger drive boss or spacers.

This morning I pulled the CVT cover, not easy, pulled some plastics removed the air box and pulled all the bolts. The belt was about 1/4 way up the variator and 1/2" down the clutch, that wouldn't do it. I pulled the drive face off and saw the belt was about 2 1/2 mm bigger at the bottom. It should be the same size so you have lots of power to get moving. I took dimensions and a washer that rides behind the ramp plate and off to Ace. There I found machine spacers, they were 1mm thick and the inside was just a little smaller that the shaft. I also found washers that were the size of the shaft but bigger than the boss. I got a bolt and nut to make a hillbilly lathe and headed home. The machine spacers were just a little smaller than the shaft but a perfect match to the drive boss. I took the dremel and slowly made the spacers a larger ID. One concern I had was whether the belt would have full travel on the variator with the shims so I put the faces together without spacers and put the belt in and it was higher than the smaller pully face. Which explains this groove in the case at the variator, there isn't much room for error here. When I put the variator together with the 2 shims it was perfectly at the top of the variator so that problem was solved. It also explained the belt thread I found in the clutch when I cleaned it. I think this was a design flaw with this variator on this model, when I looked at the parts diagram for this year the drive boss number was replaced with another number. On later years its all sold as one unit no separate boss. With the 2 shims in the belt inside was right at the edge. That looked good so I put it back together and started it and it was one noisy puppy. I pulled the CVT cover and found that the drive face hit the air deflector and scraped it. Off it came, next time I'm in there I'll sand the fins down on the drive face to get clearance. The belt was still not perfect so I tried a third spacer. Closed it up, started it again and reopened it and found the belt out past the clutch edge and way too close to the case. I didn't want to cut into the case because it was a little thin and the 2 shims got me everything I needed so I went back to 2 shims. I put it back together and took it for a ride. Problem solved, it pulls away just like it should and shifts up nicely.

Another possible way to solve this is getting thinner belt, I didn't research this but you then get into quality and other concerns. Maybe originally Piaggio had thinner belts but the wide ones are whats available 11 years later. I don't know if the Multivar or Polini variators have a larger drive boss but much larger you will hit the air deflector.

It may be a while before I open it up all the way to see how it does at wide open throttle but it definitely has nice low speed pull. This is all part of tuning a CVT, it isn't just rollers/sliders 10gr/12gr. or plug and play parts someone said would work. Its understanding how the transmission works and making yours work perfectly for your weight and driving habits. I'm just offering this to any one that has had this problem. Here are some pictures:

BV before shims.jpg
Belt in variator without the spacers

belt before shims.JPG
The belt before the spacers

belt after shims.jpg
The belt after spacers

full travel without shims.jpg
The belt with the variator all the way closed, like you were running WOT at 85mph

bv belt wear on case.jpg
What happens when the belt goes out farther than the variator edge. yes you'll go faster but at a cost of a belt breaking.

variator clearance.jpg
As you can see if your past the edge you have no place for the belt to go. Thats how they eat the gasket on the oil sump if its not trimmed.

clutch clearance 3 shim.jpg
This is why I stayed with 2 spacers.

Hooked
GTS 250ie Super, BV250, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 363
Location: Winston-Salem, NC
Thu Jun 28, 2018 3:49 pm quote
I stand corrected. I didn't put the variator back together correctly but put it together how I found it. There was a thin washer that was behind the ramp plate that goes between the drive faces that keeps the variator from closing to far. It also keeps it so that the belt goes down farther. Here is a thread that on page 4 they show the washer and talk about it. http://modernvespa.com/forum/topic103148.4?highlight=bv250+sliders. Motovista explains clearly how that washer gets left out and causes problems. My solution solves the problem as well but isn't necessary if you put it back together correctly.

So with the sliders in the scoot wasn't stopping well. It felt like it was still in gear and would eventually go to Neutral. I opened the CVT up again today and found a couple of the sliders were sticking, that would keep the variator from opening on deceleration and letting the belt drop. They weren't sticking much, just a little. I decided to go to the rollers with the stock washer in to see how it all ran. I did find that on one ramp plate no mater which roller I put in it was sticky. I sanded one weight so it moved well. I then looked at the brass bearing on the variator and it was also a little sticky, these are oil impregnated brass so it may not be moving well either. I also suspect when the belt went the Variator took a hit and thats whey the one ramp was a little smaller. A belt breaking can do damage in many ways you just never know. I put it together and went for a ride. It was much improved and ran much smoother. I feel like the stock 11 gram weights are a little light. It takes a bit of a rev to get the scoot moving. I think I will be replacing the variator with a Malossi Multivar, I have had good luck with them on other scoots. I am curious why they come with 14 and 15 gram weights but I'll see how they work. I have found that Malossi does know what they are doing and do test their products so that they work well with each scooter they go on. I'll update after I make the change.
Ossessionato
LXV 150 Midnight Blue (Sold)
Joined: 06 Dec 2010
Posts: 2695
Location: Bangkok
Thu Jun 28, 2018 5:02 pm quote
Pinkscooter wrote:
I opened the CVT up again today and found a couple of the sliders were sticking, that would keep the variator from opening on deceleration and letting the belt drop. They weren't sticking much, just a little.
On the Dr Pulley German site on the Blog pages there is a reference to some sliders having sharp edges, which can result in sticking, that should be rounded off.



Also the ramp plate may have a sharp edge produced during manufacture that can also be rounded off/deburred.



If it helps...
Hooked
GTS 250ie Super, BV250, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 363
Location: Winston-Salem, NC
Thu Jun 28, 2018 5:11 pm quote
They were sticking in the grooves they sit in. I didnít bother measuring them to see if one or more grooves had been compromised. Iíll check the other sticking points next time Iím in there.
Ossessionato
LXV 150 Midnight Blue (Sold)
Joined: 06 Dec 2010
Posts: 2695
Location: Bangkok
Thu Jun 28, 2018 5:49 pm quote
Maybe they are a tad too wide? Does BV have the same engine at GTS250?

I believe the GTS has 20.9 x 17 weights and the GT 200 20.5 x 17 I've got it recorded but don't recal where it came from.

Maybe the width of the sliders just needs to be touched up with a rub on some emery paper on a piece of glass or a floor tile?

Taking the square corners off the weights makes sense as i doubt the "grooves" in the variator have "square" corners.

Mark one of the grooves with blue felt marker then rub a slider up and down the groove to see where it touches
Member
BV250
Joined: 10 Mar 2018
Posts: 18
Location: SFBay
Thu Jul 12, 2018 8:02 pm quote
What you describe when you write that the drive line doesn't seem to disengage when you slow, and is slow to engage when you start out, is usually a rear, centrifugal clutch issue. If the two plates don't slide smoothly together and apart you can get some weird issues, and if the clutch shoes aren't swinging in and out as the pulleys slow and speed up you get this creeping and revving. Try taking the bell cover off the rear clutch and check the condition of the shoes and their springs.
Hooked
GTS 250ie Super, BV250, Italjet Velocifero, Scarabeo 150, S50,ET4
Joined: 22 Nov 2016
Posts: 363
Location: Winston-Salem, NC
Fri Jul 13, 2018 12:09 pm quote
Wentwest, that was the same conclusion I came to after looking at the variator bushing. The brass is dirty and the doesn't spin as well as it needs to. This caused the variator to not operate properly. I now have a Polini 9 roller variator waiting to be put on. Maybe today or tomorrow.
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