Modern Vespa

TL;DR Definitely time to order some new parts

Ain't this a fun graph of 42,500km of data recorded on my Supertech.

Graph is RPM @ 100kph (gps not dash) averaged over 3 day intervals. Filtered to only include above 105 as the variator should be fully maxed out by about then. EDIT: added 2nd graph which is vs Odo instead of vs Date

The distinct drops are replacements of combos of belts, rollers, pulleys. See May/2021, Dec/2022, Jul/2022, Dec/2023, Jul/2023.

I'll probably write some more about this later ...

You need to take one for the team and test to failure.

You'll make a fortune with your CVT impending doom predictor app. Have an in-app purchase option of a malossi belt from MotoV.

I am pretty hard on my scoot. I'm hoping it makes it until I get the new bits.

Mind you, I'm not always riding at high speeds. Eg a couple of days ago I was bouncing over logs and pushing though bushes.

Looks like belt wear over time. Belt get thinner so doesn't travel as far up the driven pulley.

Significant but don't underestimate the contribution of the rollers (flat spots) or the wear on the pulleys themselves (my front pulley current has .4mm wear on the var side and .3m on the fan side = .7mm wear ...)

Eg look at the mid 2022 drop - that was belt+ rollers but no pulley change

Very interesting. What does "filtered to only include above 105" mean?

RPM at 105kph, rather than 100kph?

That mid-2022 drop where the pulleys weren't changed CONTINUED to drop for a while. Then, presumably, the belt/roller wear "caught up"?

Perhaps sliders slow these effects a little bit?

Although the filter is 105 the result is @100 because all data points are scaled.

Source data is 32 million rows. After filtering to only include >=105 I get 470,000 rows. For each row RPM*100/KPH is calculated. Then rows in 3 days buckets are averaged together resulting in 139 rows. This is then graphed. In mid-2022 the service items are a bit more complex than the other intervals as during jun/jul I was testing 12g, 13g, 14g rollers plus belt change. the further drop in aug was replacing the drive pulley. Then dec was belt, rollers, driven pulley.

Regardless the trend of the overall graph vs service. interesting thought.

Although it's the importance of the wear on the pulleys that I suspect many don't think about

What does it look like with a few slabs of VB on board?
Rpm/can please.

I don't drink and ride so the slabs are always complete. Supposed I could grab some from the fridge - one more each time - and do a quick sprint on the freeway.

I havn't understood a word of this

However, the more hours I spend on the highway the more often I'd change my belt.

Im quite new to cvt's, was about to ask about if uphill and downhill would affect those rpm at 100 kmh, but at least uphill shouldnt do anything, the CVT is "locked" at maximum speed?

Ps. Just bought a -20 gts300 super few days back, had cbr1000rr earlier

Below about 100 the relationship between rpm and speed is not fixed as it depends on many things such as uphill or downhill and accelerating or decelerating etc. BUT once a steady speed is held for several seconds and on flat ground etc then the relationship is nearer to fixed - sorta (I've graphed this in another thread).

Above about 100 then the cvt will have reached its maximum and hence the relationship between rpm and speed becomes linear.

Note:

the number 100 is based on measuring my hpe. Others such as a primavera 125 could have a different point such as 80

Also I'm referring to the real speed (gps) not the speedo on a Vespa which lies

So after a CVT service, the Vespa needs less revs (about 400 less) to maintain the same speed.

That must also suggest a change in fuel economy every time the CVT is serviced?

Not necessarily. Maybe, maybe not.

There is a change in geometry, sure. But does that change in geometry make anything more efficient?

I used to track my miles per gallon rather religiously on Fuelly.
Never did notice any change when a new belt was installed.

Looks like you ride a fairly consistent amount each week but it would still be interesting to see miles or kms on the x-axis rather than time.

Also it would be interesting to see this data with (1) one component at a time changed, so the contribution of each component to the rpm drop could be more specifically attributed, and (2) with tire changes marked on the chart - shouldn't tire wear have at least a little to do with rpms at high speed?

It is intriguing that the rate of the wear is so consistent across each period, and appears to be pretty linear each time although I suppose one might infer some convexity (ie, the rpm increase tapers off a bit). You used the same components each interval? Znomit's idea of pressing on and seeing if there was some indication before the belt fails is fun to think about as long as it's somebody else's equipment.

I'm guessing the variations in this data exist because your >105 filter captures some speeds that are barely above 105, and plenty of speeds that are well above 105, so each data point will reflect a different mix of >105 speeds. Would this look different if you further constrained the upper speed to <110, and/or did another chart of speeds between 110 and 115, etc.?

I agree with that, seems more logical to me.

Steelbite,
With what equipment do you measure and record the data?

I think what you said in your first post is simple.
From that speed of roughly 100 onwards you know the transmission is at its maximum. That means the relation between speed and engine rpm is fixed.
And then you can scale linearly back to 100.

ok, will do. yes ...
.. but the big drops were when changing cvt components which is not the same times as my tire changes (mostly not) no as explained above. the calculations are ratio of rpm vs speed. not absolute values of rpm. my own app + my supertech. I wrote my own app instead of having to use piaggio's crap app. it works with all modern piaggio scoots/bikes not just the supertech.

done. added it to first post