Bad fuel economy/mileage? Check your transmission

[mousejunks]

I recently had a transmission issue where a roller got stuck. It was caused by a single roller that developed a flat spot then broke open. Thread here: https://www.kymcoforum.com/index.php?topic=33745.30. The scooter is a Kymco Downtown 350i.

Over the previous 11,000km or so, I noticed that the scooter's fuel use climbed gradually over time.

From 3.6L per 100km and before the sudden failure of the transmission, consistently 4.2 to 4.5L. Otherwise there were no obvious symptoms such as power loss, lag, vibration etc. Likely the onset of any power loss was so gradual I didn't notice it.

All caused by a single roller that wore down abnormally from a defective ramp plate and dirt build-up inside variator and didn't move properly, likely causing the variator to be in the wrong position (and therefore the wrong ratio) when accelerating and coasting. Photo attached shows the broken roller with the flat spot, plus a second roller with a minor flat spot that is not really an issue.

The rollers and ramp plate have been replaced, all the dirt cleaned out with brake cleaner and fuel consumption has returned to 3.5 to 3.7L/100km. The scooter is also more zippy with better response.

[Ruffus]

...good shot, I think.
Scoot revving slightly higher, therefore gulps...

[rjs987]

I would expect you to also note an increase in RPM for any given speed if the variator didn't move properly in this case.

When I replaced the CVT belt on my AK weekend before last I did notice there was one roller that had a VERY MINOR flat spot on it. It was barely noticeable though and there were no issues in performance so I considered it not enough to worry about... yet. The flat spot was only maybe 1-1.5 mm wide and I had to look really close and shine a light on it just right to even see it. I only noticed it because I felt around every roller with my finger while I had them out to check for any defects. So a lot smaller than what you pointed out as the second roller in your photo that you don't consider an issue. Your rollers also look a lot dirtier than mine did.

[mousejunks]

It sure has better performance after replacing all the rollers.

Not sure why the rollers are so dirty and black with some sticky dust, even with a filter.